Beta-blockers increase the risk of being born small for gestational age or of being institutionalised during infancy

To compare infant outcomes between mothers with hypertension treated by beta-blockers alone and by methyldopa alone during pregnancy.

Historical cohort study.

Saskatchewan, Canada.

Women who delivered a singleton birth in Saskatchewan during the periods from 1 January 1980 to 30 June 1987 or from 1 January 1990 to 31 December 2005 (women who delivered between 1 July 1987 and 31 December 1989 were excluded because the information recorded on maternal drug use during pregnancy is incomplete) with a diagnosis of a hypertensive disorder during pregnancy, and who were dispensed only beta-blockers (n = 416) or only methyldopa (n = 1000).

Occurrences of adverse infant outcomes were compared between women who received beta-blockers only and women who received methyldopa only during pregnancy, first in all eligible women, and then in women with chronic hypertension and in women with gestational hypertension or pre-eclampsia/eclampsia, separately. Multiple logistic regression analyses were performed to adjust for potential confounding.

Small for gestational age (SGA) < 10th percentile, SGA < 3rd percentile, preterm birth, stillbirth, institutionalisation for respiratory distress syndrome (RDS), sepsis, seizure during infancy, and infant death.

Adjusted odds ratios (aORs) and 95% confidence intervals (95% CIs) for infants born to mothers with chronic hypertension who were dispensed beta-blockers only, as compared with infants born to mothers who were dispensed methyldopa only, during pregnancy were: 1.95 (1.21-3.15), 2.17 (1.06-4.44), and 2.17 (1.09-4.34), respectively, for SGA < 10th percentile, SGA < 3rd percentile, and being institutionalised during infancy.

For infants born to mothers with chronic hypertension, compared with those treated by methyldopa alone, those treated by beta-blockers appear to be at increased rates of SGA and hospitalisation during infancy.