Association of first trimester anaesthesia with risk of congenital heart defects in offspring

Abstract

Background: A substantial number of pregnant women require anaesthesia for non-obstetric surgery, but the risk to fetal heart development is unknown. We assessed the relationship between first trimester anaesthesia and risk of congenital heart defects in offspring. Methods: We conducted a longitudinal cohort study of 2 095 300 pregnancies resulting in live births in hospitals of Quebec, Canada, between 1990 and 2016. We identified women who received general or local/regional anaesthesia in the first trimester, including anaesthesia between 3 and 8 weeks post-conception, the critical weeks of fetal cardiogenesis. The main outcome measures were critical and non-critical heart defects in offspring. We estimated risk ratios (RR) and 95% confidence intervals (CI) for the association of first trimester anaesthesia with congenital heart defects, using log-binomial regression models adjusted for maternal characteristics. Results: There were 107.3 congenital heart defects per 10 000 infants exposed to anaesthesia, compared with 87.2 per 10 000 unexposed infants. Anaesthesia between 3 and 8 weeks post-conception was associated with 1.50 times the risk of congenital heart defects (95% CI 1.11-2.03), compared with no anaesthesia. Anaesthesia between 5 and 6 weeks post-conception was associated with 1.84 times the risk (95% CI 1.10-3.08). Associations were driven mostly by general anaesthesia, which was associated with 2.49 times the risk between weeks 5 and 6 post-conception (95% CI 1.40-4.44). Conclusions: General anaesthesia during critical periods of fetal heart development may increase the risk of congenital heart defects. Further research is needed to confirm that anaesthetic agents are cardiac teratogens.