Antihypertensive medication use during pregnancy and the risk of major congenital malformations or small‐for‐gestational‐age newborns

BACKGROUND: In spite of the widespread use of antihypertensives during pregnancy, data on their risks and benefits for the newborn are limited. We investigated the risk of major congenital malformations or small-for-gestational-age newborns (SGA) in relation to gestational use of antihypertensives. METHODS: Within the Quebec Pregnancy Registry, we conducted two case-control studies. First, cases were defined as major congenital malformations diagnosed during the first year of life and controls were selected from the same cohort; index date was date of delivery. Gestational exposure was defined as filling a prescription for an antihypertensive during the 1st trimester of pregnancy. Next, cases (SGA) were defined as newborns with a birth weight <10th percentile for that gestational age and gender; controls were the newborns with a birth weight > or =10 percentile. Gestational exposure was defined as filling a prescription for an antihypertensive during the 2nd or 3rd trimester. Multivariate logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (95% CI). RESULTS: We found that overall antihypertensives use during the 2nd or 3rd trimesters of pregnancy was associated with a higher risk of SGA (OR 1.53, 95% CI 1.17-1.99). Moreover, selective beta-blocker (OR 6.00, 95% CI 1.06-33.87), alpha beta blocker (OR 2.26, 95% CI 1.04-4.88), or centrally-acting adrenergic agents use (OR 1.70, 95% CI 1.00-2.89) was associated with a higher risk of SGA compared to non-use. CONCLUSION: Gestational use of antihypertensives, especially beta-blocker, alpha beta blocker, or centrally-acting adrenergic agents, may increase the risk of SGA.