tag:theconversation.com,2011:/id/topics/morning-sickness-22393/articlesmorning sickness – The Conversation2023-12-22T09:47:25Ztag:theconversation.com,2011:article/2197072023-12-22T09:47:25Z2023-12-22T09:47:25ZMorning sickness doesn’t only occur in the morning. So why do we still call it that?<figure><img src="https://images.theconversation.com/files/565943/original/file-20231215-27-vw4i69.png?ixlib=rb-1.1.0&rect=6%2C0%2C2082%2C1384&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sick-young-woman-pain-stomach-vomiting-1575078391">Dragana Gordic/Shutterstock</a></span></figcaption></figure><p>As many as <a href="https://www.nps.org.au/assets/c54914225deb37a1-077be09b52f0-8b91fd8dbb1142caa58132e34b40b5466d337bd7268dda75dfae4a61d9f6.pdf">90%</a> or more of pregnant people experience some degree of nausea or vomiting, often colloquially referred to as “morning sickness”. </p>
<p>For some, it is relatively mild, coming and going during the first trimester without much fuss. For others, it can be severe, life-changing and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3514078/">traumatic</a>. </p>
<p>But the term “morning sickness” is a misnomer. Findings clearly show nausea and vomiting can occur throughout the day. </p>
<p>A recent and novel <a href="https://bjgp.org/content/70/697/e534.short">study</a> had pregnant women complete a symptom diary for each hour of the day across the first seven weeks of pregnancy. It found while peak symptoms occur in the morning, almost as many women experienced symptoms in the late afternoon or night as did in the morning. </p>
<p>Frequent symptoms of nausea and vomiting can become a significant problem, impacting an individual’s health, wellbeing and ability to perform basic tasks.</p>
<p>Given nausea and vomiting in pregnancy is frequently misunderstood and its effects often underestimated, its incorrect naming contributes to the stigma and lack of effective treatments faced by many women.</p>
<h2>The severe impacts of nausea and vomiting in pregnancy</h2>
<p>The most severe form of nausea and vomiting in pregnancy is called hyperemesis gravidarum and is reported to affect up to <a href="https://pubmed.ncbi.nlm.nih.gov/23863575/">3.6%</a> of pregnant women. Women with hyperemesis gravidarum have severe and persistent symptoms that can make it difficult for them to eat and drink enough. It can lead to weight loss, dehydration, and nutritional deficiencies. </p>
<p>It can also have a big impact on a person’s emotional, mental and physical health. Some people might be too sick to work, look after themselves or others, or complete normal daily activities. The economic and psychosocial effects of this can be profound. </p>
<p>In addition, <a href="https://www.ajog.org/article/S0002-9378(21)00157-5/fulltext">recent studies</a> report high rates of pregnancy termination, as well as suicidal thoughts, among hyperemesis gravidarum sufferers. This is on top of the range of <a href="https://pubmed.ncbi.nlm.nih.gov/21749625/">adverse pregnancy outcomes</a> (such as low birth weight) associated with the condition. </p>
<p>Even when not considered severe enough to constitute hyperemesis gravidarum, nausea and vomiting in pregnancy can still have profound impacts, greatly impacting women’s health, mental wellbeing, work, relationships, quality of life and experience of pregnancy. </p>
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<a href="https://images.theconversation.com/files/565921/original/file-20231214-21-9pzgmh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Woman covering her mouth at the breakfast table as though she's about to be sick." src="https://images.theconversation.com/files/565921/original/file-20231214-21-9pzgmh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565921/original/file-20231214-21-9pzgmh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565921/original/file-20231214-21-9pzgmh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565921/original/file-20231214-21-9pzgmh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565921/original/file-20231214-21-9pzgmh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565921/original/file-20231214-21-9pzgmh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565921/original/file-20231214-21-9pzgmh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Pregnancy sickness ranges in severity.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-woman-feeling-nausea-during-breakfast-2193653627">Goksi/Shutterstock</a></span>
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<h2>The stigma women face</h2>
<p>While the significant burden of nausea and vomiting highlights the importance of early and effective treatment, the reality faced by many women paints a different picture. A recent <a href="https://pubmed.ncbi.nlm.nih.gov/33984156/">Australian survey</a> found one in four respondents reported being denied medications for treating nausea or hyperemesis. </p>
<p>In part, this could reflect the ongoing hesitancy towards using medications during pregnancy since the <a href="https://theconversation.com/thalidomide-survivors-are-receiving-an-apology-for-the-pharmaceutical-disaster-that-changed-pregnancy-medicine-218691">thalidomide tragedy</a> in the 1960s. But it also reflects the enduring stigma those experiencing nausea and vomiting in pregnancy face when trying to receive care.</p>
<p>As recently as the early 1900s, the root cause of nausea and vomiting in pregnancy was thought to be psychological. Journal articles referred to “<a href="https://history-of-obgyn.com/uploads/3/5/4/8/35483599/1905-stevens-hyperemesis_obs-rev-jun2015.pdf">hysteria</a>” as a principal cause of nausea and vomiting, and of individuals <a href="https://pubmed.ncbi.nlm.nih.gov/13289940/">manifesting</a> symptoms as a result of being unhappy with their pregnancy or marriage, or seeking attention.</p>
<p>These erroneous beliefs have led to various dismissive and damaging practices resulting in women feeling isolated and unsupported. A <a href="https://pubmed.ncbi.nlm.nih.gov/15550881/">2004 French study</a> reported treating women admitted to hospital for hyperemesis gravidarum by subjecting them to isolation from friends or family to see if they would reveal their “secret desire” for an abortion.</p>
<p><a href="https://news.cornell.edu/stories/2000/05/morning-sickness-protects-mothers-and-their-unborn">Biologists</a> have argued nausea and vomiting in pregnancy serves a beneficial function to protect mothers and their unborn children from potentially harmful exposures. In part, this is based on evidence those experiencing nausea and vomiting in pregnancy are <a href="https://pubmed.ncbi.nlm.nih.gov/2611170/">less likely to have a miscarriage</a>.</p>
<p>While it seems to be accurate that nausea and vomiting in pregnancy has benefits, this argument presents it as a “rite of passage” and something individuals should welcome, while trivialising its associated burden.</p>
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Read more:
<a href="https://theconversation.com/thalidomide-survivors-are-receiving-an-apology-for-the-pharmaceutical-disaster-that-changed-pregnancy-medicine-218691">Thalidomide survivors are receiving an apology for the pharmaceutical disaster that changed pregnancy medicine</a>
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<h2>How should nausea and vomiting in pregnancy be defined?</h2>
<p>While nausea and vomiting in pregnancy is common, when prolonged it can quickly become a debilitating medical condition. It’s important individuals experiencing nausea and vomiting in pregnancy are listened to and get the treatment they need, rather than being dismissed. </p>
<p><a href="https://www.somanz.org/content/uploads/2023/12/SOMANZ-Management-of-NVP-ExecSummary-Updated-Oct-2023-FINAL.pdf">Guidelines</a> often recommend using screening tools which classify individuals as having mild, moderate or severe nausea and vomiting based on responses to three questions about how they have been feeling over the past 24 hours. </p>
<p>While tools like this can be useful to guide or monitor treatment, they can risk causing further harm if used to restrict access to care based on perceived symptom severity. It’s crucial that treatment decisions not be based solely on a number, but rather on a comprehensive evaluation of an individual’s emotional, mental and physical health.</p>
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<a href="https://images.theconversation.com/files/565932/original/file-20231215-23-4euq92.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Pregnant stomach" src="https://images.theconversation.com/files/565932/original/file-20231215-23-4euq92.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565932/original/file-20231215-23-4euq92.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565932/original/file-20231215-23-4euq92.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565932/original/file-20231215-23-4euq92.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565932/original/file-20231215-23-4euq92.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565932/original/file-20231215-23-4euq92.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565932/original/file-20231215-23-4euq92.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Pregnancy sickness should be seen as an illness to be managed, not a rite of passage.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-young-pregnant-woman-touching-her-2115089237">SeventyFour/Shutterstock</a></span>
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<h2>Time to retire the term ‘morning sickness’</h2>
<p>A term that incorrectly describes the nature and spectrum of an illness can be expected to further perpetuate stigmas faced by those seeking clinical care. Given it’s well recognised the term is felt by many to downplay the condition, we must ask ourselves why we continue to use the term “morning sickness”. </p>
<p>This description is inaccurate, simplistic, and therefore unhelpful. Referring to the illness by what it is, nausea and vomiting in pregnancy or “NVP”, could reduce stigma and lead to better outcomes for sufferers.</p>
<p>Perhaps more important is recognition that not all nausea and vomiting in pregnancy is experienced equally, and treating it as such risks trivialising the experience of each individual.</p><img src="https://counter.theconversation.com/content/219707/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Luke Grzeskowiak receives funding from the Channel 7 Children's Research Foundation, The Hospital Research Foundation and National Health and Medical Research Council. </span></em></p><p class="fine-print"><em><span>Hannah Jackson receives an Australian Government Research Training Program Stipend from the University of Technology Sydney.</span></em></p>We know nausea and vomiting is common all times of day during pregnancy. Calling it morning sickness contributes to the stigma and misunderstanding of the condition.Luke Grzeskowiak, Fellow in Medicines Use and Safety, Flinders UniversityHannah Jackson, University of Technology SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2196632023-12-14T13:19:15Z2023-12-14T13:19:15ZWe think we have found a cause of pregnancy sickness, and it may lead to a treatment<figure><img src="https://images.theconversation.com/files/565507/original/file-20231213-19-swroox.jpg?ixlib=rb-1.1.0&rect=48%2C0%2C5351%2C3540&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pregnancy sickness is believed to affect 7 in 10 women. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/woman-suffering-morning-sickness-bathroom-home-1041217495">Monkey Business Images/Shutterstock</a></span></figcaption></figure><p>Sickness in pregnancy, or hyperemesis gravidarum, is common and is thought to <a href="https://journals.lww.com/obgynsurvey/abstract/2013/09001/the_impact_of_nausea_and_vomiting_of_pregnancy_on.1.aspx">affect</a> seven out of ten women at some time in their pregnancy. But, until recently, very little has been known about why it happens. </p>
<p><a href="https://www.nature.com/articles/s41586-023-06921-9">New research</a> by our team has identified sensitivity to a hormone made in abundance by the developing pregnancy, GDF15, as a contributor to the risk of pregnancy sickness.</p>
<p>This condition can affect pregnant women’s quality of life, even in so-called mild cases. Between 1% and 3% of women <a href="https://pubmed.ncbi.nlm.nih.gov/31515515/">suffer</a> from a severe form of pregnancy sickness when nausea and vomiting are so severe that they lose weight or become dehydrated, or both. In one study, this condition was the most common reason that women were admitted to <a href="https://pubmed.ncbi.nlm.nih.gov/12100809/">hospital</a> in the first three months of pregnancy. </p>
<p>It has been <a href="https://onlinelibrary.wiley.com/doi/10.1111/ppe.12416">associated</a> with worse pregnancy outcomes and its effect lasts beyond the end of pregnancy with some women <a href="https://pubmed.ncbi.nlm.nih.gov/21635201/">reporting</a> psychological distress and being reluctant to <a href="https://pubmed.ncbi.nlm.nih.gov/28241811/">conceive again</a>. </p>
<p>The fact that it develops in early pregnancy and invariably resolves when pregnancy ends strongly suggests that the cause of the sickness comes from the developing pregnancy. But the detail on how and why it happens has remained elusive. This dearth of understanding makes the development of treatments difficult and arguably contributes to the considerable <a href="https://www.pregnancysicknesssupport.org.uk/documents/research%20papers/stigma-of-hg.pdf">stigma</a> associated with this condition. </p>
<h2>GDF15</h2>
<p>GDF15 is a hormone that suppresses food intake in mice by acting, probably exclusively, on a small group of cells at the base of the brain which are also known to induce nausea and vomiting. As such, GDF15 has been under investigation as an <a href="https://pubmed.ncbi.nlm.nih.gov/36754014/">obesity therapy</a>. </p>
<p>Early trials confirm it suppresses appetite in people, but it also causes <a href="https://pubmed.ncbi.nlm.nih.gov/36630958/">nausea and vomiting</a>. It has long been known that it is abundant in human placenta and is present at very high concentrations in the blood of healthy pregnant women. These factors make it a plausible cause, but a detailed understanding of if GDF15 affects the severity of sickness in pregnancy has been lacking. </p>
<p>We used a variety of methods to study how GDF15 increases the risk of pregnancy sickness. We measured GDF15 in the blood of pregnant women attending hospital due to sickness and those attending hospital for other reasons. </p>
<p>We found that women with pregnancy sickness did indeed have higher levels of GDF15. While this was in keeping with GDF15 contributing to the condition, levels of GDF15 in each group overlapped substantially. This suggests that factors other than the absolute amount of GDF15 coming from the developing pregnancy might determine the risk of sickness.</p>
<p>Natural variation in DNA of future mothers contributes to risk of pregnancy sickness. Previous <a href="https://pubmed.ncbi.nlm.nih.gov/29563502/">studies</a> have identified changes in DNA near GDF15 as the biggest determinants of risk of pregnancy sickness. In particular, one rare genetic mutation (present in around one in 1,500 people) that affects the make-up of the GDF15 protein in the blood, has a large <a href="https://pubmed.ncbi.nlm.nih.gov/35218128/">effect</a> on that risk. </p>
<p>To understand the potential impact of this genetic variant on GDF15 levels in the bloodstream, we studied its effects on the protein in lab-grown cells. We discovered that this mutated GDF15 molecule gets stuck inside cells. What’s more, it actually stuck to and trapped “normal” GDF15 – this creates a double hit that hinders the transport of GDF15 out of cells. Healthy people with this mutation have markedly lower levels of GDF15 in their blood, which is consistent with these findings.</p>
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<img alt="A pregnant woman sits on the edge of a bed clutching her bump." src="https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565574/original/file-20231213-21-z851cx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Between 1% and 3% of women suffer from a severe form of pregnancy sickness.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/pregnant-woman-sitting-on-bed-holding-310309151">Monkey Business Images/Shutterstock</a></span>
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<p>We discovered that DNA changes near GDF15, which are prevalent in about 15 to 30% of people, lower the levels of the hormone. These changes increase the risk of pregnancy sickness by small amounts. Conversely, women with the blood disorder <a href="https://www.nhs.uk/conditions/thalassaemia/">thalassaemia</a>, who have very high levels of GDF15 throughout life, actually reported much less nausea and vomiting in pregnancy.</p>
<h2>A roadmap to treatment</h2>
<p>The conclusion of these studies is clear –- predisposition to higher levels of GDF15 when not pregnant reduces the risk of pregnancy sickness. At first glance, this is rather perplexing because how can having higher levels of a hormone that makes you sick protect against pregnancy sickness? </p>
<p>In fact, several hormone systems exhibit a phenomenon resembling memory, where the sensitivity to a hormone is influenced by previous exposure to that hormone. This seemed like the most plausible explanation for our results. Supporting this theory, mice with persistently high levels of GDF15 in their bloodstream were relatively unresponsive to an acute surge in GDF15 levels. </p>
<p>Our findings suggest that lower levels of GDF15 before pregnancy result in women being hypersensitive to the large amounts of GDF15 being released from the developing pregnancy. This poses two obvious approaches to treatment of this condition –- desensitising women to GDF15 by increasing its levels before pregnancy or blocking its action during pregnancy. </p>
<p>The challenge now is to develop and test strategies to achieve these aims that are safe and acceptable to women at risk from this debilitating condition.</p><img src="https://counter.theconversation.com/content/219663/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sam Lockhart is supported by a Wellcome Trust Clinical PhD Fellowship (225479/Z/22). SL is a named creator of a pending patent application relating to therapy for hyperemesis gravidarum filed by Cambridge Enterprise Limited (GB application No. 2304716.0; Inventor: Professor Stephen O’Rahilly.</span></em></p><p class="fine-print"><em><span>Stephen O'Rahilly has undertaken remunerated consultancy work for Pfizer, Third Rock Ventures, AstraZeneca, NorthSea Therapeutics and Courage Therapeutics. Part of the work in this paper is the subject of a pending patent application relating to therapy for hyperemesis gravidarum filed by Cambridge Enterprise Limited (GB application No. 2304716.0; Inventor: Professor Stephen O’Rahilly). SL and NR are named creators on this patent.</span></em></p>New research has uncovered the hormone that triggers morning sickness, offering hope for millions of women.Sam Lockhart, Wellcome Trust Clinical PhD Fellow, Institute of Metabolic Science and Medical Research Council Metabolic Diseases Unit, University of CambridgeStephen O'Rahilly, Professor and Co-Director of the Institute of Metabolic Science and Director of the Medical Research Council Metabolic Diseases Unit, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/467092016-12-12T03:38:03Z2016-12-12T03:38:03ZWhen nausea from pregnancy is life-threatening<figure><img src="https://images.theconversation.com/files/105342/original/image-20151210-7463-18w1o4i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-293488796/stock-photo-female-patients-were-treated-with-saline-and-stay-in-front.html?src=b5N0I12-Gul6kQRQrXthOg-1-19">Woman with IV image via www.shutterstock.com.</a></span></figcaption></figure><p>Most women experience some type of morning sickness during pregnancy, but some women develop a far more serious condition.</p>
<p>Hyperemesis gravidarum (HG), which causes severe nausea and vomiting during pregnancy, affects as many as <a href="https://www.acog.org/-/media/For-Patients/faq126.pdf">3 percent of pregnancies</a>, leading to over <a href="http://www.ajog.org/article/S0002-9378(11)01851-5/fulltext">167,000 emergency department</a> visits each year in the U.S.</p>
<p>Until intravenous hydration was introduced in the 1950s, it was <a href="https://www.ncbi.nlm.nih.gov/pubmed/4877794">the leading cause of maternal death</a>. Now, it is the <a href="https://www.ncbi.nlm.nih.gov/pubmed/12100809">second leading cause</a>, after preterm labor, of hospitalization during pregnancy. </p>
<p>And yet, the disease is neither well-understood nor well-known, even with the flurry of headlines when it was announced that the Duchess of Cambridge during her pregnancies <a href="http://www.theguardian.com/uk-news/she-said/2014/sep/27/hyperemesis-gravidarum-kate-middletons-ongoing-condition-is-much-worse-than-just-morning-sickness">suffered from the condition</a>. </p>
<p>I decided to start researching HG in 1999 after losing a baby at 15 weeks of gestation due to constant violent vomiting. I found that there was surprisingly little research on this disease. </p>
<p>To date, I’ve been contacted by over 4,400 pregnant women worldwide and have collected extensive survey data and saliva samples from women with HG and their unaffected friends. Analysis of these data has enabled me to answer some of the most pressing questions about the disease. </p>
<h2>How is this different from morning sickness?</h2>
<p>Even though HG is prevalent, many women don’t know about it until they experience it themselves. Symptoms can include extreme nausea and vomiting, as well as rapid weight loss, dehydration, electrolyte imbalance, dizziness and excessive saliva. Some women may start to vomit blood or bile and may require intravenous fluids and medication. </p>
<p>Some of the women I have encountered in my research on HG experience vomiting so violent that their retinas have detached, their ribs have fractured, their eardrums have burst, their esophagi have torn, their fingernails have fallen off and in rare cases, they can suffer from brain damage from malnutrition. </p>
<p>HG cannot be controlled by small frequent meals and saltine crackers – common recommendations for women with morning sickness. HG can also last for much longer than morning sickness.</p>
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<img alt="" src="https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/121284/original/image-20160504-19847-169q0c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">HG can have consequences for mother and child.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-334218644/stock-photo-a-pregnant-girl-doing-on-ultrasound-examination.html?src=klsCYM6qCxtb7ndcoDcfNQ-2-74">Pregnant women ultrasound image via www.shutterstock.com.</a></span>
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</figure>
<p>The old wives’ tale that the baby gets everything it needs from the mother even if she is unable to eat or drink or take vitamins is false. </p>
<p>Population studies of neural tube defects and animal studies, as well as studies of human offspring born during famine, in addition to those exposed to HG, now prove that malnutrition in early pregnancy can be linked to long-term health consequences in the exposed fetus. </p>
<p>Children exposed to HG in utero have a three-fold increased risk of <a href="http://dx.doi.org/10.1016/j.ejogrb.2015.03.028">neurodevelopmental delay</a>. Research shows early symptoms of HG were linked to delay, which suggests early vitamin and nutrient deficiencies may be at play.</p>
<p>For <a href="http://dx.doi.org/10.1016/j.ejogrb.2013.04.017">women with HG</a> there is a four-fold increased risk of adverse outcomes, such as preterm birth, and a <a href="http://dx.doi.org/10.1017/S2040174411000249">3.6-fold increased lifetime risk</a> of emotional disorders, such as depression and anxiety. </p>
<p>The effects of HG can <a href="https://www.ncbi.nlm.nih.gov/pubmed/27460690">last long after birth</a>. In one survey we found a significant increased risk of chronic postpartum symptoms in women with HG including reflux, anxiety, depression, insomnia, fatigue and muscle pain, and 18 percent experienced the full criteria of <a href="http://dx.doi.org/10.3109/14767058.2011.582904">post-traumatic stress symptoms</a>.</p>
<p>And HG can also lead to Wernicke’s Encephalopathy (WE), a severe neurological condition caused by a deficiency in thiamin (vitamin B1). Over a dozen cases were <a href="https://www.ncbi.nlm.nih.gov/pubmed/24701066">published in the medical literature between 2012-2014</a>, and recently maternal deaths caused by complications from HG including Wernicke’s Encephalopathy <a href="http://scientonline.org/open-access/mortality-secondary-to-hyperemesis-gravidarum-a-case-report.pdf">have been documented in the U.S., England and Africa</a>. </p>
<p>In a survey of over 800 women with HG, more than <a href="http://dx.doi.org/10.1016/j.contraception.2007.08.009">one in seven women with HG decided</a> to terminate the pregnancy, primarily because they had no hope for relief from the condition.</p>
<h2>How is HG treated?</h2>
<p>Accurate data about what drugs can treat HG effectively and safely are hard to come by. This is due, in part, to the thalidomide disaster of the 1950s, when the drug was prescribed to women with HG to relieve symptoms of nausea and babies were born with limb deformities. This led to difficulty in developing and testing medications on pregnant women.</p>
<p>So what do the limited available data say? A study I conducted with colleagues found that antihistamine use to treat HG has been linked to <a href="http://dx.doi.org/10.1016/j.ejogrb.2013.04.017">preterm birth</a>. We also found that Ondansetron (Zofran) is effective in treating HG symptoms for more than 50 percent of the women in our studies. We have also found that potentially serious side effects in women taking the drug, such as <a href="http://dx.doi.org/10.1016/j.reprotox.2015.07.071">intestinal obstructions</a>, are rare. In recent research, we found <a href="http://dx.doi.org/10.1016/j.reprotox.2016.04.027">no evidence to support a link</a> between ondansetron and birth defects.</p>
<p>But we do know this: Women with HG who are losing weight in pregnancy, and are unable to tolerate food or vitamins for more than a week, should be treated not only with fluids but also with thiamin to avoid the rare but preventable progression to WE, as well as maternal or fetal death. </p>
<p>Caretakers, family members and patients themselves may lean toward termination of a wanted pregnancy rather than try a medication of unknown safety. So for women with HG, seeking treatment can be a fraught experience. </p>
<p>A centralized, national database to document cases of HG, treatments and medications and their effectiveness, and maternal and child outcomes could help us figure out which medications are safe and effective in treating HG. This would increase patient and provider confidence about using treatments during pregnancy. It would also reduce the risk of malpractice or class action suits, which make drug companies and doctors hesitant to test and prescribe new treatments. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/121283/original/image-20160504-17469-iq55rq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We need more - and better - research to treat HG.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-310309151/stock-photo-pregnant-woman-sitting-on-bed-holding-belly.html?src=xtU8OxjZOTYoYgJlzpDfEQ-1-88">Pregnant woman via www.shutterstock.com.</a></span>
</figcaption>
</figure>
<h2>We need to know what causes HG to treat it</h2>
<p>Years of research, primarily focusing on hormones, have failed to identify what causes HG, and consequently, a clinically proven safe and effective treatment has yet to be found. </p>
<p>Currently, the leading hypothesis is that pregnancy hormones cause nausea and vomiting, and genetic and environmental factors that influence susceptibility to nausea and vomiting may turn normal pregnancy nausea into hyperemesis. </p>
<p>Increasing evidence suggests a genetic component to HG. If a woman has HG during one pregnancy there is about an <a href="http://dx.doi.org/10.1111/j.1542-2011.2010.00019.x">80 percent risk of recurrence</a> in a subsequent pregnancy. The risk of recurrence is not affected by <a href="http://dx.doi.org/10.3109/14767058.2011.632039">change in partner</a> or <a href="http://www.ncbi.nlm.nih.gov/pubmed/25345812">psychiatric factors</a>. The greatest risk factor for HG (besides having a previous HG pregnancy) is having a sister with HG, which constitutes <a href="http://dx.doi.org/0.1016/j.ajog.2010.09.018">a 17-fold increased risk</a>.</p>
<p>A common misconception is that if a woman is the only one in her family with HG, it is not genetic. However, our research suggests the gene or genes responsible are <a href="https://dx.doi.org/0.1016/j.ajog.2010.09.018">equally likely to be passed from</a> the paternal line as the maternal line. In <a href="https://dx.doi.org/10.1016/j.mce.2016.09.017">a recent study</a> of five families with a history of HG, we found a gene that signals vomiting in two of them. In addition, HG may be caused by a combination of several genes. A woman with HG may be the only one in her family with a pregnancy history that carries a particular combination of predisposing genes. </p>
<p>Once we identify the genetic and associated biological causes of HG, further research will likely help us develop therapies that target these causes of the condition, rather than blindly and rather ineffectively treating symptoms.</p><img src="https://counter.theconversation.com/content/46709/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marlena Schoenberg Fejzo has received funding from and is a science advisor for the Hyperemesis Education and Research Foundation (HelpHer.org). </span></em></p>Hyperemesis gravidarum causes severe nausea and vomiting during pregnancy. Even though it affects up to 3 percent of pregnancies, research about its causes and treatments is sparse.Marlena Schoenberg Fejzo, Associate Researcher in Medicine, University of California, Los AngelesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/550392016-08-29T04:19:43Z2016-08-29T04:19:43ZHealth Check: what can you eat to help ease ‘morning’ sickness in pregnancy?<figure><img src="https://images.theconversation.com/files/128179/original/image-20160626-28382-i2kl9e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ginger may help milder levels of nausea and vomiting in pregnancy</span> <span class="attribution"><span class="source">by rebeccacharlotte.com.au</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Nausea and vomiting in pregnancy is mistakenly known as “morning” sickness. Mistakenly, because it doesn’t occur only in the morning. One <a href="http://www.sciencedirect.com/science/article/pii/S0002937800703498">Canadian study</a> reported 80% of its sample of pregnant women experienced nausea that lasted all day, compared to only 1.8% who reported it occurring just in the morning. However, half of pregnant women in <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1372422/">a British study</a> did vomit in the morning, between 6am and 12pm.</p>
<p>The exact cause of the nausea and vomiting in pregnancy is <a href="http://www.ncbi.nlm.nih.gov/pubmed/25162163">unknown</a>, although various <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3676933/">factors</a> and <a href="http://www.ncbi.nlm.nih.gov/pubmed/12011885">hypotheses</a> have been suggested.</p>
<p>The <a href="http://www.journals.uchicago.edu/doi/10.1086/393377">most popular evolutionary hypothesis</a> linked to nutrition seems to be that nausea and vomiting may have protected pregnant mothers and their unborn children against potentially harmful substances in food. Imagine you’re a pregnant, hairy woman who feels too sick to try that new, delicious-looking plant that has just started to grow on your cavestep.</p>
<p>Negative effects of pregnancy nausea on mum can <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3676933/">include</a> <a href="http://www.sciencedirect.com/science/article/pii/S0020748907002027">stress</a>, <a href="http://www.ncbi.nlm.nih.gov/pubmed/18655256">anxiety and depression</a>, an inability to work, malnutrition, dehydration, <a href="http://www.ncbi.nlm.nih.gov/pubmed/27261898">contribution to constipation</a>, decreased <a href="http://www.ncbi.nlm.nih.gov/pubmed/12011890">quality of life</a> and irritability, increased sleep disturbances and <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3676933/">lowered mood</a>.</p>
<h2>What should you eat?</h2>
<p>It can be hard to eat a <a href="https://www.eatforhealth.gov.au/eating-well/healthy-eating-throughout-all-life/healthy-eating-when-you%E2%80%99re-pregnant-or-breastfeeding">balanced diet</a> when you are suffering from nausea and vomiting. You may only feel like oranges, hot chips, lemonade, ice blocks and pizza. </p>
<p>It’s best not to worry too much about this in the short term (beginning mid-pregnancy), as you can catch up with better nutrition when you start to feel more human. It’s better to eat anything than nothing at all. </p>
<p>It’s important to note some foods <a href="https://theconversation.com/health-check-what-to-eat-and-avoid-during-pregnancy-30356">should be avoided</a> during pregnancy. It’s also important to note more reflux-associated nausea and vomiting that may occur later in pregnancy comes with its own list of <a href="http://onlinelibrary.wiley.com/enhanced/doi/10.1111/j.1365-2036.2005.02654.x/">nutrition tips</a>. These can be different to those for earlier nausea and vomiting. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/128181/original/image-20160626-28388-aa961r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/128181/original/image-20160626-28388-aa961r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/128181/original/image-20160626-28388-aa961r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/128181/original/image-20160626-28388-aa961r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/128181/original/image-20160626-28388-aa961r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/128181/original/image-20160626-28388-aa961r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/128181/original/image-20160626-28388-aa961r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Approximately three-quarters of mums experience nausea and vomiting in pregnancy.</span>
<span class="attribution"><span class="source">by rebeccacharlotte.com.au, Author provided</span></span>
</figcaption>
</figure>
<p>The tips include eating smaller meals; not eating late at night; not consuming alcohol, fizzy drinks or other reflux-promoting <a href="http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0016453/">foods and drinks</a> such as spicy or fatty foods and peppermint; and chewing gum. </p>
<p>Even if you only manage to eat some chips and drink lemonade while you suffer from early nausea and vomiting, are there certain things you can eat or drink – or nutrition supplements you can take – that may help ease your symptoms? </p>
<p>There are <a href="http://www.health.gov.au/internet/main/publishing.nsf/Content/phd-antenatal-care-index">lots of</a> <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD007575.pub4/abstract">reviews</a> and <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD010607.pub2/abstract">guidelines</a> on the nutritional management of nausea and vomiting in pregnancy. But there doesn’t seem to be enough <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD007575.pub4/abstract">high-quality evidence</a> to be able to confidently recommend any particular nutrition strategy widely. </p>
<p>There are <a href="https://www.nps.org.au/australian-prescriber/articles/treatment-of-nausea-and-vomiting-in-pregnancy">common nutrition practices</a> that <em>may</em> help and are widely used by women all over the world. Many have good anecdotal support but <a href="http://www.aafp.org/afp/2014/0615/p965.html">few have been investigated in scientific studies</a>. That doesn’t mean they don’t work, though. Some of the common tips in the literature are:</p>
<ul>
<li>identify and avoid things that you find triggering </li>
<li>avoid having an empty stomach</li>
<li>keep some bland food like dry crackers by your bedside and have a few before getting up in the morning</li>
<li>eat small amounts of food often and avoid large meals </li>
<li>eat at times when you feel less nauseous (although you will likely have to force yourself at times to eat when you feel nauseous, as it may be the only thing that makes you feel better)</li>
<li>avoid spicy and fatty foods, which can irritate the stomach and/or decrease the rate of stomach emptying</li>
<li>avoid foods with strong smells (your sense of smell can become very heightened while pregnant and some smells may make you feel sick – including food smells)</li>
<li>cold or frozen drinks or foods are often better tolerated</li>
<li>have foods and fluids at separate times to decrease the volume in your stomach</li>
<li>drink small amounts of fluid often, but try to have about two litres daily (especially if you’re vomiting)</li>
<li>herbal teas (such as ginger) may help.</li>
</ul>
<p>There has been more research into certain nutrition supplements. These also may improve nausea and vomiting symptoms – although the evidence is not yet robust enough for wide application:</p>
<ul>
<li><p><a href="http://www.health.gov.au/internet/publications/publishing.nsf/Content/clinical-practice-guidelines-ac-mod1%7Epart-b%7Eclinical-assessments+%7Enausea">Ginger</a> as syrup or capsules up to 250mg four times a day may help, appears to be safe and is <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3676933/">recommended in America</a>. However, it is not recommended in <a href="http://www.health.gov.au/internet/publications/publishing.nsf/Content/clinical-practice-guidelines-ac-mod1%7Epart-b%7Eclinical-assessments+%7Enausea">Australian Clinical Practice Guidelines</a>.</p></li>
<li><p>Vitamin B6 (pyridoxine) <a href="http://www.aafp.org/afp/2014/0615/p965.html">may improve nausea</a> at a dose of 10-25mg every eight hours, or <a href="https://www.nps.org.au/australian-prescriber/articles/treatment-of-nausea-and-vomiting-in-pregnancy">25-50mg orally</a> up to four times daily (200mg per day has been shown to be safe). Again, this is not recommended in <a href="http://www.health.gov.au/internet/publications/publishing.nsf/Content/clinical-practice-guidelines-ac-mod1%7Epart-b%7Eclinical-assessments+%7Enausea">Australian Clinical Practice Guidelines</a>.</p></li>
<li><p>Discontinuation of iron or multivitamin supplements is recommended in the <a href="http://www.health.gov.au/internet/publications/publishing.nsf/Content/clinical-practice-guidelines-ac-mod1%7Epart-b%7Eclinical-assessments+%7Enausea">Australian Clinical Practice Guidelines</a>, as these may contribute to nausea.</p></li>
</ul>
<p>If your nausea and vomiting are more severe, then the above strategies may do absolutely nothing for you. You may need to move onto pharmaceutical and other management options. These include the anti-nausea drug <a href="http://www.nps.org.au/medicines/brain-and-nervous-system/nausea-and-vomiting-medicines/ondansetron-nausea-and-vomiting-medicines">ondansetron</a>, which evidence suggests is <a href="http://www.ncbi.nlm.nih.gov/pubmed/27054939">unlikely</a> to have any severe adverse effects on baby – unlike <a href="http://www.nejm.org/doi/pdf/10.1056/NEJM196212132672407">thalidomide</a> in times gone by. </p>
<p>Even though almost three-quarters of <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1479-828X.2008.00865.x/abstract?userIsAuthenticated=false&deniedAccessCustomisedMessage=">Australian women</a> may use at least one kind of “complementary therapy” during pregnancy, such as acupressure travel bands or acupuncture, the evidence for most is <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1523-536X.2009.00329.x/abstract?userIsAuthenticated=false&deniedAccessCustomisedMessage=">inconclusive</a>.</p><img src="https://counter.theconversation.com/content/55039/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr Reynolds is a registered nutritionist with the Nutrition Society of Australia and the owner of The Real Bok Choy <a href="http://www.therealbokchoy.com">www.therealbokchoy.com</a>, a nutrition and lifestyle consultancy.</span></em></p>It can be hard to eat a balanced diet when you are suffering from nausea and vomiting. You may only feel like oranges, hot chips, lemonade, ice blocks and pizza.Rebecca Reynolds, Lecturer in Nutrition, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/502352015-11-10T12:09:50Z2015-11-10T12:09:50ZWhat happens to your brain when you’re pregnant – morning sickness, smell and forgetfulness?<figure><img src="https://images.theconversation.com/files/101044/original/image-20151106-16273-xkzzpl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">www.shutterstock.com</span></span></figcaption></figure><p>My friend recently asked me: “Why have I become so forgetful since I became pregnant?” I told her I didn’t know, but that I’d look into it. She then followed with: “I was going to ask you to explain something else to me, but I totally forgot what it was.” </p>
<p>It’s a common claim that pregnancy makes you forgetful. But does “pregnancy brain” actually exist? There’s no doubt that many changes happen to a woman’s body during pregnancy, but how do these changes affect – or originate in – the brain? To answer my friend’s question, and in an effort to address whatever else she was forgetting at the time, here is part one of my expectant mother’s guide to the crazy neuroscience of pregnancy.</p>
<h2>Morning sickness</h2>
<p>More than half – perhaps even <a href="http://www.webmd.com/baby/features/battle-morning-sickness">up to 90%</a> – of pregnant women experience nausea or vomiting to some degree, particularly in the morning. Thrust into the limelight as a result of the <a href="http://www.theguardian.com/uk-news/she-said/2014/sep/27/hyperemesis-gravidarum-kate-middletons-ongoing-condition-is-much-worse-than-just-morning-sickness">Duchess of Cambridge’s hospitalisations</a>, around 1% of pregnant women experience more severe, prolonged morning sickness called hyperemesis gravidarum, which can result in dehydration and weight loss, and may require medical attention. For most women, morning sickness goes away after 18 weeks.</p>
<p>The cause of morning sickness isn’t entirely clear. The most popular theory is that morning sickness is the body’s reaction to the increase in the pregnancy hormone, human chorionic gonadotropic (hCG). Studies have shown a <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3676933/">temporal relationship</a> between hCG and morning sickness, meaning that levels of hCG in the bloodstream and frequency of vomiting appear to peak at the same time. The correlation is interesting, but it doesn’t explain why morning sickness happens. </p>
<p>We do know that the first three months (the first trimester) is an important time in foetal development. The central nervous system forms during this time, and this delicate process is <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2274963/">easily disrupted by toxins</a> circulating in the mother’s bloodstream. <a href="http://www.jstor.org/stable/10.1086/588081">A more recent theory</a> suggests that vomiting during early pregnancy serves a beneficial function by ridding the body of food that may unsettle this important developmental stage. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/101440/original/image-20151110-21206-by8q19.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/101440/original/image-20151110-21206-by8q19.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/101440/original/image-20151110-21206-by8q19.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/101440/original/image-20151110-21206-by8q19.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/101440/original/image-20151110-21206-by8q19.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/101440/original/image-20151110-21206-by8q19.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/101440/original/image-20151110-21206-by8q19.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">But can science throw up any answers?</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-164314280/stock-photo-young-woman-vomiting-into-the-toilet-bowl-in-the-early-stages-of-pregnancy-or-after-a-night-of.html?src=cV7p2kwqFFNFxKTlummMqg-1-18">Morning sickness by Shutterstock</a></span>
</figcaption>
</figure>
<p>Vomiting is controlled by an area in the hindbrain called the area postrema. Importantly, the area postrema lacks a blood-brain barrier, which means it can detect toxins in the bloodstream and cerebrospinal fluid. Research has shown that the <a href="http://www.ncbi.nlm.nih.gov/pubmed/11394198">area postrema has receptors for hCG</a>, which may explain why it’s particularly sensitive during pregnancy. </p>
<p>This “toxin theory” is supported by <a href="http://www.jstor.org/stable/10.1086/588081">several pieces of evidence</a>, including the fact that morning sickness is more common in societies with “risky foods”, that it only occurs in humans (we have very broad diets, after all), and that more severe morning sickness is associated with lower rates of miscarriage. Many women also naturally tend to be more “turned off” to eating meat, fish, and certain plants during this time. </p>
<p>Of course, these so-called toxins are really not toxic at all to healthy adult women, and <a href="http://www.nhs.uk/chq/Pages/2309.aspx?CategoryID=54#close">the placenta</a> does a superb job of filtering out waste and fighting infection. Rather, morning sickness is likely more associated with foods prone to microorganisms in the times before refrigeration (like meats), or bitter vegetables, the taste of which signalled “poison” to our early human ancestors. It’s a sensitive system, and despite how crappy it makes pregnant women feel, morning sickness probably provides an evolutionary advantage for the baby’s development.</p>
<h2>Stronger sense of smell</h2>
<p>According to many women, a heightened sense of smell, called hyperosmia, is one of their earliest signs of pregnancy. Although anecdotes of hyperosmia have existed for a century, scientific literature on the topic is sparse. Subjectively, around <a href="http://www.ncbi.nlm.nih.gov/pubmed/17634389/">two-thirds of women</a> rate their sense of smell as stronger than usual while pregnant. <a href="http://www.ncbi.nlm.nih.gov/pubmed/15201206/">Another study reported</a> that, compared with women who aren’t pregnant, pregnant women are particularly sensitive to odours such as cooking foods, cigarette smoke, spoiled food, perfumes, and spices. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/101310/original/image-20151109-29312-t89f41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/101310/original/image-20151109-29312-t89f41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/101310/original/image-20151109-29312-t89f41.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/101310/original/image-20151109-29312-t89f41.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/101310/original/image-20151109-29312-t89f41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/101310/original/image-20151109-29312-t89f41.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/101310/original/image-20151109-29312-t89f41.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ooh! That’s bad!</span>
<span class="attribution"><span class="source">www.shutterstock.com</span></span>
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</figure>
<p><a href="http://www.ncbi.nlm.nih.gov/pubmed/11788167/">A few studies</a> have examined scent detection thresholds (the smallest volume of air that still results in odour detection) in pregnant versus non-pregnant women. But, in a <a href="http://www.ncbi.nlm.nih.gov/pubmed/12584889/">study where six different scents</a> were tested, there was no difference in detection threshold between the two groups.</p>
<p>Given the inconsistency between subjective and objective reports on hyperosmia, research suggests that pregnant women don’t necessarily have a stronger sense of smell, but are perhaps better at <em>identifying</em> smells. <a href="http://www.ncbi.nlm.nih.gov/pubmed/17634389/">A recent study</a> found that pregnant women were more likely to rate a variety of smells as significantly less pleasant than non-pregnant women. Early in pregnancy – much like the body rejects foods that may be toxic to the developing foetus – it appears that <a href="http://www.sciencedirect.com/science/article/pii/S1090513804001072">women have a greater “disgust sensitivity”</a> that motivates them to avoid other possible contaminants. That may explain why things like cigarette smoke and spoiled food become particularly pungent.</p>
<p>As with morning sickness, there’s a link between the timing of hCG levels and when a woman’s odour perception changes. But it’s thought that these hormonal changes aren’t affecting our noses. When a Swedish research group presented scents to pregnant and non-pregnant women and <a href="http://www.ncbi.nlm.nih.gov/pubmed/16112693">measured their brains’ responses</a>, they found a larger amplitude and shorter latency in the P300 wave of pregnant women, a voltage change [thought to reflect neural processes](https://en.wikipedia.org/wiki/P300_(neuroscience) related to a person’s assessment and evaluation of an event. This suggests that hormonal changes may be acting on higher-order cognitive processes related to our perception of odours.</p>
<h2>The question about forgetfulness</h2>
<p>While a number of women – like my friend – complain that pregnancy has made them more forgetful than usual, the research on this topic is mixed. Like most changes that occur during pregnancy, hormonal fluctuations are an obvious possible culprit. Some women report no cognitive changes during pregnancy.</p>
<p>A <a href="http://www.tandfonline.com/doi/abs/10.1080/13803390701612209">2008 meta-analysis</a> reported that, compared with women who weren’t pregnant, pregnant women perform worse on some measures of memory. In particular, pregnant women tend to perform worse on working (short-term) memory and free recall tasks.</p>
<p>In a <a href="http://www.sciencedirect.com/science/article/pii/S0278262613001668">study published in 2014</a>, researchers in the UK administered a spatial recognition memory task to non-pregnant women, as well as to women during each trimester of their pregnancy. Compared with their first trimester, pregnant women scored, on average, 11.7% lower on the memory tasks with each subsequent trimester. When the researchers compared memory test scores to levels of six different hormones measured from blood plasma, however, there was no association – in other words, hormones may not be playing a role in these memory deficits.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/101442/original/image-20151110-21228-14gvfeg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/101442/original/image-20151110-21228-14gvfeg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=350&fit=crop&dpr=1 600w, https://images.theconversation.com/files/101442/original/image-20151110-21228-14gvfeg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=350&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/101442/original/image-20151110-21228-14gvfeg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=350&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/101442/original/image-20151110-21228-14gvfeg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=440&fit=crop&dpr=1 754w, https://images.theconversation.com/files/101442/original/image-20151110-21228-14gvfeg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=440&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/101442/original/image-20151110-21228-14gvfeg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=440&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Baby rat – what was happening in its mother’s hippocampus?</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-322107494/stock-photo-portrait-of-a-baby-rat-on-glass.html?src=O6fZKoJzA_LZI3CFSBvjNQ-1-52">Rat by Shutterstock</a></span>
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<p>Interestingly, <a href="http://www.nature.com/mp/journal/v13/n5/full/4002126a.html">a 2008 study</a> reported a decrease in neurogenesis, or birth of new neurons, in the hippocampus of mice during pregnancy. The hippocampus is involved in consolidation of short-term to long-term memory, as well as spatial navigation, such as remembering where you parked your car. Similarly, <a href="http://www.ncbi.nlm.nih.gov/pubmed/10712861">an earlier study</a> showed no differences in brain sizes between pregnant and non-pregnant rats except for the hippocampus. The hippocampus was smaller in pregnant rats, and also related to deficits in spatial memory. No studies have imaged the brains of pregnant woman to examine potential changes in the human hippocampus, though.</p>
<p>Some have postulated that sleep deprivation or the new-found stress of dealing with a major life change could contribute to absentmindedness during pregnancy. <a href="http://onlinelibrary.wiley.com/doi/10.1002/acp.1427/abstract">Some research</a> suggests that there’s a cultural expectation at play, as the popular concept of “pregnancy brain” may simply make women more aware of their everyday slip-ups. A change in daily routine with a new pregnancy might disrupt some women’s memory abilities, too. </p>
<p>Although there’s a lot we don’t know about all the crazy changes that happen during pregnancy, one thing is clear: babies do a great job of making their presence known well before they come kicking and screaming into the world.</p>
<p><em>You can read <a href="https://theconversation.com/what-happens-to-your-brain-when-youre-pregnant-clumsiness-food-cravings-and-moodiness-55011">Pregnancy Brain part two here</a> which covers clumsiness, cravings, and moodiness. If there’s anything else that you’d like me to write about, let me know in the comments</em></p><img src="https://counter.theconversation.com/content/50235/count.gif" alt="The Conversation" width="1" height="1" />
Part one: morning sickness, sense of smell, and forgetfulness.Jordan Gaines Lewis, Neuroscience Doctoral Candidate, Penn StateLicensed as Creative Commons – attribution, no derivatives.