Labetalol, nifedipine equally effective for chronic hypertension in pregnancy

Treatment with either labetalol or nifedipine is similarly effective in reducing adverse maternal outcomes among women with mild chronic hypertension (CHTN) in pregnancy, according to a study presented at SMFM 2023.

“Both labetalol and nifedipine are the recommended first-line medications for the treatment of CHTN in pregnancy,” said Dr Ayodeji Sanusi from the University of Alabama at Birmingham, Alabama, US. However, there are limited data available comparing these antihypertensive agents for antepartum treatment of mild CHTN.

The researchers conducted a planned secondary analysis of the CHAP* trial involving 2,292 patients (mean age 32 years) with mild CHTN (BP of <160/105 mm Hg) and singleton pregnancies at <23 weeks of gestation. Participants were randomized to receive antihypertensive medication with either labetalol 200 mg twice daily (n=720) or nifedipine 30 mg once daily (n=417) during pregnancy, while the remaining 1,155 patients did not receive any treatment (control group). [SMFM 2023, abstract 17]

In this analysis, the risks of the primary outcome, comprising a composite of preterm birth <35 weeks’ gestation, severe pre-eclampsia, foetal or neonatal death, and placental abruption, were comparable between the labetalol and nifedipine groups (30 percent vs 31 percent; relative risk [RR], 0.97).

Compared with nontreated patients, both labetalol- and nifedipine-treated patients achieved a lower risk of the primary composite outcome (30 percent vs 37 percent; RR, 0.82 and 31 percent vs 37 percent; RR, 0.84, respectively).

With regard to adverse neonatal outcomes, there was no difference in the composite risk of bronchopulmonary dysplasia, retinopathy of prematurity, necrotizing enterocolitis, and grade 3 or 4 intraventricular haemorrhage among the three groups (2 percent each in the labetalol and nifedipine groups and 3 percent in the no treatment group).

Similarly, the risk of neonates being small-for-gestational-age (<10^th percentile) and requiring any respiratory support as well as the frequency of NICU** admission did not differ in all groups.

Sanusi noted that the study has some limitations, including the small number of patients receiving nifedipine at baseline that limited the power to detect differences in the nifedipine group.

However, the clinically relevant question for most practitioners and patients is what medications should be initiated, since the use of antihypertensive medications during pregnancy cannot be reliably predicted, said Sanusi.

Overall, the findings of this study showed that antihypertensive treatment with either labetalol or nifedipine reduced the risk of adverse maternal outcomes, with no safety signals identified, for the treatment of mild CHTN in pregnancy.

Additionally, labetalol and nifedipine are equally safe and effective in treating this patient population, Sanusi noted.

*CHAP: Chronic Hypertension and Pregnancy

**NICU: Neonatal intensive care unit