Babies conceived through in vitro fertilisation (IVF) mostly grow up to be healthy adults and compare well to those conceived naturally, according to research my colleagues and I have just published in the journal Fertility and Sterility.
There are outstanding questions about the long-term safety of IVF because there’s a possibility of early development being disturbed through the process. That’s because it involves hormonal stimulation, fertilisation outside the human body and culturing the embryo for a couple of days before it’s transferred to the uterus.
It’s already well recognised that IVF-conceived babies are at an increased risk of preterm birth and lower birth weight than other children.
Any such suggestion of an impact on early development highlights the need to study the impact on later health, because we know health and disease are impacted by our developmental origins. That means what happens in the womb can have significant influence on later health, particularly heart health.
Another major reason for our research lies in the fact that assisted reproduction is becoming more common, with almost 4% of pregnancies resulting from such interventions. Until now, we didn’t know about the longer-term safety of this complex technology being applied at such a fragile stage of development.
A lot of research has been done on the birth period, early childhood and even adolescence, but most research stops by the mid teens.
There’s consensus about the increased risk of birth defects for IVF babies, although this is a small increase from a small base, and there are mixed findings in relation to measures of growth, cardiovascular health and neurodevelopment.
But around the world, there have been very few studies of older children conceived with IVF, especially over 18 years of age.
The Australian state of Victoria, where my colleagues and I are based, was the epicentre of IVF in the 1980s so we were in the unique position to access what in other places is a scattered population. And we were able to secure help from many of the doctors who provided IVF services back then to follow up a large group of young adults.
We interviewed 656 mothers, who’d used IVF, about the health and well-being of their child in the first 18 years of life. With their permission, we also spoke to 547 young adult offspring, who were aged between 18 and 29. The responses were then compared to data collected using the same interview questions with 868 non-IVF mothers and their 549 young adult offspring.
Our study showed children who were conceived using IVF had similar quality of life to non-IVF children, along with a normal body mass index and history of pubertal development. Educational outcomes, including tertiary admission ranked scores and completion of tertiary education, were also similar between the two groups.
But the results suggested IVF children had a higher rate of hospitalisation, as well as a higher rate of asthma and hay fever. The reasons for hospitalisations were varied, with no consistent set of conditions. And there was no evidence for increased rates of any other serious health or development problems.
We did find that IVF children had a slightly higher chance of asthma and other respiratory allergies, such as hay fever, which are common conditions in the whole community. But the difference was small with 30% for IVF children and 23% for others.
This association has also been found in other studies and remains unexplained. It may have something to do with the IVF treatment itself, or the infertility that led to the intervention, but there could also be a number of non birth-related reasons for it.
It may be because IVF parents took their children to the doctor more often, for instance, so asthma was diagnosed at a higher rate. Or because IVF parents were very protective of their “special baby” and reduced their exposure to dust and dirt, which is thought to put people at higher risk of for later allergies (hygiene hypothesis).
While our results are reassuring, we will need to follow up with another that uses a more objective measures rather than relying on self-reporting. We plan to assess the group’s fertility and continue evaluating their health status to determine if there are any important lifelong medical or other legacies of IVF.
Nonetheless, we are now confident that most IVF offspring have grown into healthy young adults with a quality of life and educational achievement comparable to those of non-IVF conceived peers.