Infertility, not just treatment, may shape birth outcomes, finds study of 1.4M births

SOURCE: ICES

Infertility is the inability to conceive after 12 months of regular, unprotected sexual intercourse; some patients with infertility are still able to conceive without fertility treatment. Infants born to those with infertility face a higher risk of congenital anomalies compared to unassisted conception, according to a new study from ICES, Queen’s University and the Research Institute of the McGill University Health Centre (The Institute).

In the study of 1,415,324 births, 1,185,299 were conceived without assistance and 230,025 by women with infertility who did not use treatment. Among these births the prevalence of congenital anomalies was 5.3 per cent in infants from unassisted conceptions compared with 5.9 per cent in the latter cohort. Some of these observed anomalies include cleft palates, heart defects, and kidney malformations.

The findings suggest that, although the risk of congenital anomalies was low, there was an increased risk for infants born to women with infertility but did not use fertility treatment to conceive.

“Our intention is not to alarm expecting mothers. Rather, we should consider how the underlying causes of infertility—such as endometriosis, polyendocrine metabolic ovarian syndrome (PMOS, formerly known as PCOS), paternal factors, and others—may influence fetal development, so that future research can better understand the biological mechanisms underlying these associations and identify opportunities to improve maternal and child health,” says Bailey Milne, lead author of the study and an ICES doctoral student.

Past research compared pregnancies conceived through fertility treatments with unassisted conceptions, capturing both treatment effects and underlying fertility on congenital anomalies. However, the same reproductive issues that prompt individuals to seek fertility treatment may themselves influence this risk. For example, endometriosis is a well-established cause of infertility, and recent work from our team suggests that it may also be associated with an increased risk of congenital anomalies in offspring.

“As the proportion of births conceived through fertility treatment technologies continues to grow, studies evaluating the safety of existing and emerging fertility technologies should compare these pregnancies with those conceived by patients with infertility who did not undergo fertility treatment,” adds Dr. Maria Velez, senior author, Scientist at The Institute and Associate Professor, Department of Obstetrics and Gynecology, Faculty of Medicine and Health Sciences, McGill University.

The study “Infertility and risk of congenital anomalies: a population-based cohort study” is in the August issue of Paediatric and Perinatal Epidemiology.