Maternal use of β-blockers in the first trimester is not associated with a large increase in the risk for overall malformations or cardiac malformations, a recent study found. The international cohort study included pregnant women from health registries in the 5 Nordic countries and the US Medicaid database with a diagnosis of hypertension and their offspring. First-trimester exposure to β-blockers was assessed. Outcomes were any major congenital malformation, cardiac malformations, cleft lip or palate, and central nervous system (CNS) malformations. Researchers found:

• Of 3,577 women with hypertensive pregnancies in the Nordic cohort and 14,900 in the US cohort, 682 (19.1%) and 1,668 (11.2%), respectively, were exposed to β-blockers in the first trimester.
• Pooled adjusted relative risk (RR) and risk difference per 1,000 persons exposed associated with β-blockers were 1.07 and 3.0, respectively, for any malformation, 1.12 and 2.1 for any cardiac malformation, and 1.97 and 1.0 for cleft lip or palate.
• The adjusted RR was 1.37 for CNS malformations and the risk difference per 1,000 persons exposed was 1.0.