Treatment with oral beta-blockers during pregnancy complicated by maternal heart disease increases the risk of fetal growth restriction

ObjectiveTo investigate the effect on fetal growth of treatment with oral beta-blockers during pregnancy in women with congenital or acquired heart disease. DesignHistorical matched cohort study. SettingCentre for Pregnant Women with Heart Disease, Copenhagen University Hospital, Denmark. PopulationA cohort of 175 women with heart disease, grouped according to beta-blocker treatment, and a cohort of 627 women from the overall population matched on seven birthweight-determining factors. MethodsDifferences between groups were tested by simple descriptive statistics and assessed using standard hypothesis tests. Associations were estimated by correlational analysis and multivariable regression. Main outcome measureProportion of infants born small for gestational age (SGA). ResultsMore of the infants exposed to beta-blockers were SGA compared with non-exposed infants (29.4 versus 15.3%; P<0.05). After adjustment for birthweight-determining factors, beta-blocker treatment and maternal body mass index (BMI) were the only factors independently associated with SGA (the relative difference in expected birthweight was -8.6%; 95%CI -13.3 to -3.9%; P=0.0004). After adjustment for BMI, beta-blocker treatment was associated with an increased risk of SGA (OR2.65; 95%CI 1.15-6.10; P=0.02). In a subgroup with isolated tachyarrhythmias, SGA infants were more frequent in the beta-blocker exposed group compared with the non-exposed group (31 versus 10%; P<0.005). Beta-blocker treatment was the only independent predictor of SGA, adjusting for several factors influencing fetal growth (the relative difference in expected birthweight was -12.2%; 95%CI -19.9 to -3.9%; P=0.001). ConclusionsIn a historical cohort of pregnancies complicated by maternal heart disease, treatment with beta-blockers was found to be independently associated with an increased risk of delivering an SGA infant.