Treatment of mild chronic hypertension during pregnancy is beneficial

Reference

Tita AT, Szychowski JM, Boggess K, et al, for the Chronic Hypertension and Pregnancy (CHAP) Trial Consortium. Treatment for mild chronic hypertension during pregnancy. N Engl J Med 2022;386(19):1781-1791.

Synopsis

This was a multicenter randomized clinical trial comparing the treatment of mild chronic hypertension in pregnancy with no treatment. The investigators included 2408 pregnant women with a gestational age of less than 23 weeks and a known or new diagnosis of chronic hypertension. Mild chronic hypertension was defined as at least 2 blood pressure measurements, taken at least 4 hours apart and before 20 weeks' gestation, of 140 mm Hg to 159 mm Hg systolic or 90 mm Hg to 104 mm Hg diastolic (without antihypertensive medication). Patients with blood pressure of less than 140/90 were eligible if they had prior diagnosis of chronic hypertension. The authors excluded patients with severe hypertension, chronic antihypertensive treatment with more than one medication, known secondary hypertension, multiple gestation, and multiple maternal and fetal complications. The majority of patients were taking antihypertensive medications at the time of enrollment. The authors randomized participants to a blood pressure goal of 140/90 or to a control group. The control group stopped taking antihypertensive medication unless blood pressure measurements were at least 160 mm Hg systolic and/or at least 105 diastolic. If severe hypertension was identified among control patients, treatment was initiated with a target of less than 140/90, as in the active treatment group. Treatment was with labetalol or extended-release nifedipine, preferentially, with dose titration or additional medication, as needed. Amlodipine and methyldopa were also permitted. The primary outcome was a composite of preeclampsia with severe features occurring up to 2 weeks after delivery, medically indicated preterm birth at less than 35 weeks', placental abruption, and fetal/neonatal death. A primary outcome event occurred less frequently in the active treatment group (353/1170 [30.2%] vs 427/1155 [37.0%]; relative risk 0.82; 95% CI 0.73 - 0.92; P < .001; number needed to treat = 15; 9 - 34). The most frequent components of the primary outcome were preeclampsia with severe features and medically indicated preterm birth, each of which was statistically significant. The safety outcome of neonatal birthweight of less than the 10th percentile was similar between groups. Severe neonatal complications did not differ between groups.