A randomised placebo controlled trial of labetalol in the treatment of mild to moderate pregnancy induced hypertension

Abstract

Objective: To determine the need for, and efficacy of, treatment with labetalol in women with mild-to-moderate pregnancy induced hypertension (PIH).

Design: Prospective double-blind randomised placebo controlled study.

Setting: Maternity units of five hospitals in the Trent Region.

Subjects: 144 women (86 primigravid) who developed PIH after 20 weeks gestation.

Interventions: Treatment with oral labetalol up to 600 mg daily or placebo with subsequent care of treatment failures in accordance with the attending obstetrician's practice.

Main outcome measures: Number of days spent as an antenatal inpatient; the development of proteinuria; the perceived need for induction of labour or elective caesarean section; and gestation age at delivery.

Results: Labetalol significantly lowered the blood pressure and reduced the incidence of proteinuria. However, neither the number of days spent as an antenatal inpatient, nor the perceived need for induction of delivery or elective caesarean section, nor the gestation age at delivery differed significantly between the two treatment groups. Post-randomisation consideration of early (< or = 32 weeks) and late (> 32 weeks) onset groups showed the placebo treated early-onset group (n = 15) to have more patients with severe hypertension (> 150/110 mmHg) and a greater requirement for additional antihypertensive therapy prior to labour than the group treated with labetalol (n = 16).

Conclusion: Anti-hypertensive intervention therapy in pregnancy induced hypertension has been examined using a placebo controlled randomised double-blind trial of labetalol in pregnancy. The maximum blood pressure prior to labour and the incidence of proteinuria was reduced in women on active therapy. However, the length of gestation was not significantly prolonged and indices of clinical outcome were not significantly altered. The appropriateness of pharmacological therapy for late-onset PIH may be questioned.