Assisted reproductive technology and birth defects in a Chinese birth cohort study.

Background: It has been consistently shown in several meta-analyses that infants born after ART have an excess of birth defects compared with those after spontaneous conception, however, the prevalence of birth defects among ART offspring in China is incompletely studied. Moreover, it is unclear to what extent the risk of birth defects is associated with parental infertility characteristics, specific ART procedures and twinning.

Methods: In the prospective cohort study, we included women who participated in the cohort, and had pregnancies of at least 20 gestational weeks between August 2016 and May 2019, and followed them until their children reached 1 year of age. Exposures of interest were ART, as well as infertility-related characteristics, certain ART procedures and specific medication usage. The primary outcome was birth defects including both major and minor defects, which we analysed with logistic generalized estimating equations to investigate the association with ART and certain ART characteristics.

Findings: A total of 1,825 women with ART-pregnancy and 3,483 women with spontaneous-pregnancy were included in the analysis. The prevalence of any defects was significantly higher among ART-births than their non-ART counterparts at each follow-up, specifically at prenatal screening (2•2% vs. 1•2%), at delivery (4•9% vs. 2•9%), at 6 months (10•4% vs. 5•3%) and 1 year of age (13•9% vs. 7•0%), and the associations between ART and increased risk of birth defects at each follow-up were similarly robust. Among ART-births, GnRH antagonist regimen for ovulation induction in women was associated with an increased risk of birth defects in their offspring after taking into account potential influencing factors (Multivariable model: adjusted risk ratio [aRR] 1•47, 1•04-2•07). Additionally, mediation through twinning accounted for 31•1% of the risk of ART-associated birth defects.

Interpretation: The results suggest that ART confers an increased risk for birth defects in offspring. The risk is partly attributable to infertility characteristics, certain ovulation induction regimen, and to some extent mediated by twinning. Our findings highlight the importance of long-term follow-up of children conceived via ART for health conditions.

Funding: National Key Research and Development Program of China, National Natural Science Foundation of China and Natural Science Foundation of Jiangsu Province.