Treatment for chronic hypertension in pregnancy with labetalol showed no significant differences in maternal or neonatal outcomes, compared with treatment with nifedipine, new research indicates.
The open-label, multicenter, randomized CHAP (Chronic Hypertension in Pregnancy) trial showed that treating mild chronic hypertension was better than delaying treatment until severe hypertension developed, but still unclear was whether, or to what extent, the choice of first-line treatment affected outcomes.
Researchers, led by Ayodeji A. Sanusi, MD, MPH, with the Division of Maternal and Fetal Medicine at the University of Alabama at Birmingham, conducted a secondary analysis of CHAP to compare the primary treatments. Mild chronic hypertension in the study was defined as blood pressure of 140-159/90-104 mmHg before 20 weeks of gestation.
Three Comparisons
Three comparisons were performed in 2292 participants based on medications prescribed at enrollment: 720 (31.4%) received labetalol; 417 (18.2%) initially received nifedipine; and 1155 (50.4%) had standard care. Labetalol was compared with standard care; nifedipine was compared with standard care; and labetalol was compared with nifedipine.
The primary outcome was occurrence of superimposed preeclampsia with severe features; preterm birth before 35 weeks of gestation; placental abruption; or fetal or neonatal death. The key secondary outcome was a small-for-gestational age neonate. Researchers also compared adverse effects between groups.
Among the results were the following:
- The primary outcome occurred in 30.1% in the labetalol group; 31.2% in the nifedipine group; and 37% in the standard care group.
- Risk of the primary outcome was lower among those receiving treatment. For labetalol vs standard care, the adjusted relative risk (RR) was 0.82; 95% confidence interval (CI), 0.72-0.94. For nifedipine vs standard care, the adjusted RR was 0.84; 95% CI, 0.71-0.99. There was no significant difference in risk when labetalol was compared with nifedipine (adjusted RR, 0.98; 95% CI, 0.82-1.18).
- There were no significant differences in numbers of small-for-gestational age neonates or serious adverse events between those who received labetalol and those using nifedipine.
Any adverse events were significantly more common with nifedipine, compared with labetalol (35.7% vs 28.3%, P = .009), and with nifedipine, compared with standard care (35.7% vs 26.3%, P = .0003). Adverse event rates were not significantly higher with labetalol when compared with standard care (28.3% vs 26.3%, P = .34). The most frequently reported adverse events were headache, medication intolerance, dizziness, nausea, dyspepsia, neonatal jaundice, and vomiting.
“Thus, labetalol compared with nifedipine appeared to have fewer adverse events and to be better tolerated,” the authors write. They note that labetalol, a third-generation mixed alpha- and beta-adrenergic antagonist, is contraindicated for those who have obstructive pulmonary disease and nifedipine, a dihydropyridine calcium channel blocker, is contraindicated in people with tachycardia.
The authors write that their results align with other studies that have not found differences between labetalol and nifedipine. “[O]ur findings support the use of either labetalol or nifedipine as initial first-line agents for the management of mild chronic hypertension in pregnancy to reduce the risk of adverse maternal and other perinatal outcomes with no increased risk of fetal harm,” the authors write.
Dr. Sanusi reports no relevant financial relationships. Full coauthor disclosures are available with the full text of the paper.