USE OF LABETALOL IN PREGNANCY

Labetalol is a non-selective beta-blocker with additional alpha adrenoceptor blocking properties. It is licensed for the treatment of mild to severe hypertension, hypertension in pregnancy, and angina pectoris with existing hypertension. NICE guidelines state that where clinically appropriate, labetalol is recommended as first-line antihypertensive treatment in pregnancy.

Data on overall rates of fetal structural malformation following first trimester use of labetalol are too limited to permit an evidence-based risk assessment. Although single studies have found no association between gestational exposure to labetalol and congenital heart defects or hypospadias, these findings remain to be confirmed. It is noteworthy that while some women with chronic hypertension may be switched to labetalol during early pregnancy, gestational hypertension is, by definition, diagnosed after 20 gestational weeks and its treatment will therefore pose a low risk of structural anomaly.

Overall, the available studies do not suggest that gestational labetalol exposure increases the risks of fetal growth restriction or preterm delivery; however, because maternal hypertension is associated with both of these outcomes, analysis is complex. Very limited data do not raise concern that gestational labetalol exposure increases the risk of stillbirth, but this remains to be confirmed. Data on rates of miscarriage and neurodevelopmental outcomes are too limited to permit a risk assessment.

Use of beta-blockers near term may result in beta-adrenoceptor blockade, leading to neonatal bradycardia, hypotension and hypoglycaemia. Although data are conflicting, with some studies not identifying increased risks, one large study which utilised advanced methods to control for confounding variables described 1.8- and 1.3-fold increased risks of neonatal hypoglycaemia and bradycardia respectively following maternal use of labetalol in pregnancy. Assessment of the neonate for these effects is therefore advised.

Exposure to labetalol at any stage in pregnancy would not usually be regarded as medical grounds for termination of pregnancy. In pregnancies complicated by maternal hypertension and/or where labetalol has been administered, careful monitoring of fetal growth is advised. Other risk factors may also be present in individual cases which may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of considering such factors when performing case-specific risk assessments.