Comparing IVF babies to the general population when they grow up
Given the prevalence of assisted reproductive technology (ART) and IVF in particular, it’s easy to forget how new all this technology really is. The first IVF baby was born in 1978, so most of the resulting offspring are relatively young. This means there haven’t been a lot of great studies that follow these children into adulthood to look for long-term medical or cognitive impairments. Not to mention the fact that it’s really hard to follow these people through the years and keep a representative sample.
But a study from Israel managed to take a deep and unique look at young adults who were born through IVF. They assessed each person’s medical and mental health, along with cognitive ability. The good news is that, for the most part, no news was good news!
Why This Study Is Special
Israelis are in a unique position to perform studies like this, because they followed young adults who were enlisting in the military -- military service is mandatory, and everyone goes through a rigorous pre-draft evaluation of their medical and psychiatric history. This basically eliminates selection and participation bias that would raise questions in many studies. Also, IVF is free in Israel, so there’s no socioeconomic bias. As part of the military service, these individuals are monitored very closely -- their full records are computerized and kept together with recruitment, medical, and service records.
This study followed almost all the IVF children born from a single IVF center from 1982 - 1993. In total, 253 adolescents aged 16 to 20 were compared with a very similar, naturally-conceived cohort from the military. Of the IVF children, 158 were singletons, and 95 were part of multiple deliveries.
What Was Tracked & What They Found
Because they had so much data to work with, there were a LOT of factors evaluated. They looked at all medical and psychiatric diagnoses recorded in profiles, including blood pressure, diabetes, renal disease, obesity, thyroid disorders, GI disorders, asthma, anxiety disorders, and even migraines. They also measured cognitive function through IQ testing. Finally, all medical appointments throughout military service were recorded.
On just about every single parameter, there were no meaningful differences. Great news!
There were a few minor differences. Here’s a good one: adolescents conceived through IVF had a lower rate of discharge from military service for health reasons than the control group, and their reasons for exemption were typically personality disorders and behavior, versus more serious medical issues in the comparison group.
Another positive: the IVF group scored slightly higher in cognitive function.
One difference that’s tough to interpret: the IVF adolescents had significantly more doctor’s appointments during their service than their peers. It’s unclear though, whether this means they truly had more medical issues. It’s easy to imagine a scenario where this group had been brought up in families who more regularly seek medical attention, but that’s just pure hypothesis (the study didn’t investigate the causality).
Finally, ART multiples were significantly thinner, with lower BMI than ART singletons or the comparison population, though that’s not entirely surprising.
There have been several earlier, conflicting studies about whether IVF children have different rates of asthma, blood pressure issues, or even height than their naturally-conceived counterparts, but most of those studies typically focus on younger children. In this study, there were no such differences (including height!).
The Study’s Limitations
Of course, no study is perfect. While this is a huge number for a longitudinal study like this, it’s still a low sample size at 253 individuals studied. They were all born from a single IVF center in Israel, so there’s no way to account for the differences in treatment offered at other centers, and treatment has obviously changed substantially since these people were born in the 1980’s and early 1990’s. It also lumps all types of ART together, so it’s impossible to say, for example, if adult offspring of ICSI fared differently from IVF without ICSI (though, side note, if you’re interested in that particular topic, there’s a new study you should check out that showed adult women born from ICSI had the same reproductive health markers as the general population, and this article shows the broader studies of ICSI health implications).
The small sample size also means there’s not meaningful data on rare diseases, so if those are more common amongst children of IVF, this study wouldn’t necessarily show it.
Finally, this study only looked at young adults, which presumes that all of them survived to adulthood. We know that infertility itself, and ART, is associated with an increased risk of fetal malformation, perinatal complications like preterm delivery, and perinatal mortality, and this study isn’t looking at those realities that come in the shorter-term following fertility treatment.
It’s rare to see a study that follows up on a population so rigorously, and tracks so many different health parameters. The fact that cognitive function and just about every health indicator from visual acuity to asthma didn’t show meaningful differences seems like a big positive for those considering long-term implications.