Fertility treatment is not the cause of adverse birth outcomes in babies born after medically assisted reproduction.
Children conceived through fertility treatment are more likely to be born premature and with a lower birth weight. However, the causes behind these adverse birth outcomes are unclear. In a comparative study, researchers performed a within-family analysis by focusing on a group of families who had conceived both naturally and through medically assisted reproduction. They found limited evidence of the effects of assisted reproduction on birth outcomes in the sibling comparison analysis, which is in line with existing studies.
‘Rather than the infertility treatment itself, our new findings highlight the importance of parents’ underlying fertility problems and health conditions, and infants’ birth characteristics, such as their birth order and whether they are a twin, on birth weight and pregnancy term’, said the first author of the study Dr Alina Pelikh, a research fellow at the Centre for Longitudinal Studies, University College London (UCL).
The study published in the journal Obstetrics & Gynecology analysed 248,013 deliveries between 2009 and 2017 in Utah. Around five percent of births resulted from assisted reproduction. More invasive methods such as IVF were associated with worse birth outcomes such as low birth weight, or preterm birth.
However, researchers found the mothers’ health, parents’ socioeconomic background, and infants’ birth characteristics accounted for a significant amount of the differences in birth outcomes.
The researchers then only considered a subgroup of women who conceived siblings via both assisted reproduction and natural conception. Once various factors were taken into account, the difference between siblings’ birth weights and pregnancy terms was not found significant, suggesting there are other factors to explain adverse outcomes in babies conceived through assisted reproduction.
‘Obtaining similar results in highly diverse contexts – in terms of demographics, fertility rates and access to the medically assisted reproduction treatments – strengthens the argument that adverse birth outcomes among medically assisted reproduction conceived infants are unlikely to be driven by the reproductive technology itself,’ added lead author Dr Alice Goisis, an associate professor of demography in the Centre for Longitudinal Studies, UCL.
‘This new evidence can go on to enrich existing health guidance about the risks and benefits of infertility treatments, hopefully raising awareness among families who are thinking about using medically assisted reproduction to help them conceive.’
by Tsvetana Stoilova