Chronic Hypertension and Pregnancy - CHAP

Contribution To Literature:

The CHAP trial showed that antihypertensive therapy improves pregnancy outcomes among pregnant women with mild chronic hypertension.


The goal of the trial was to evaluate antihypertensive therapy compared with control among pregnant women with mild chronic hypertension.

Study Design

  • Randomized
  • Parallel
  • Open-label

Pregnant individuals with mild chronic hypertension were randomized to a blood pressure goal <140/90 mm Hg (active treatment) (n = 1,208) versus control (n = 1,200). In the control group, antihypertensive therapy was withheld unless the blood pressure was ≥160/105 mm Hg.

In the active treatment group, patients received standard first-line antihypertensive agents in pregnancy (labetalol or extended-release nifedipine); however, amlodipine or methyldopa could also be used, if needed. The medication was titrated to the maximum dose, as necessary, before starting a second agent.

  • Total number of enrollees: 2,408
  • Duration of follow-up: 34 weeks
  • Mean patient age: 32 years
  • Percentage with diabetes: 15.8%

Inclusion criteria:

  • Pregnant women with mild chronic hypertension
  • Known chronic hypertension was confirmed by elevated blood pressure and previous/current antihypertensive therapy, while new chronic hypertension was defined as systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 on ≥2 occasions ≥4 hours apart
  • Gestational age <23 weeks

Exclusion criteria:

  • Need for >1 antihypertensive medication, secondary hypertension, multiple fetuses, high-risk illnesses, or complications that could warrant treatment at a lower blood pressure level
  • Obstetric conditions that increase fetal risk
  • Contraindications to first-line antihypertensive drugs in pregnancy

Other salient features/characteristics:

  • Non-Hispanic black women: 48%
  • Mean body mass index: 37.5 kg/m2
  • Mean systolic blood pressure between randomization and delivery: 129.5 mm Hg in the active treatment group vs. 132.6 mm Hg in the control group

Principal Findings:

The primary outcome, composite of pre-eclampsia with severe features, medically indicated preterm birth at <35 weeks’ gestation, placental abruption, or fetal/neonatal death, occurred in 30.2% of the active treatment group vs. 37.0% of the control group (p < 0.001).

Secondary outcomes:

  • The safety outcome, small-for-gestational-age birth weight below the 10th percentile for gestational age: 11.2% in the active treatment group vs. 10.4% in the control group (p = 0.56)
  • Pre-eclampsia with severe features: 23.3% in the active treatment group vs. 29.1% in the control group
  • Fatal/neonatal death: 3.5% in the active treatment group vs. 4.3% in the control group


Among pregnant women with mild chronic hypertension, antihypertensive therapy targeted to a blood pressure <140/90 mm Hg reduced the incidence of adverse pregnancy outcomes compared with usual care. Active treatment improved outcomes without increasing the risk for low birth weight. A large proportion of non-Hispanic blacks were enrolled in this trial.


Tita AT, Szychowski JM, Boggess K, et al., on behalf of the Chronic Hypertension and Pregnancy (CHAP) Trial Consortium. Treatment for Mild Chronic Hypertension During Pregnancy. N Engl J Med 2022;386:1781-92.

Editorial: Greene MF, Williams WW. Treating Hypertension in Pregnancy. N Engl J Med 2022;386:1846-7.

Presented by Dr. Alan Tita at the American College of Cardiology Annual Scientific Session (ACC 2022), Washington, DC, April 2, 2022.

Clinical Topics: Congenital Heart Disease and Pediatric Cardiology, Prevention, CHD and Pediatrics and Arrhythmias, CHD and Pediatrics and Prevention, Hypertension

Keywords: Abruptio Placentae, ACC22, ACC Annual Scientific Session, Amlodipine, Antihypertensive Agents, Blood Pressure, Gestational Age, Hypertension, Infant, Infant, Low Birth Weight, Infant, Newborn, Labetalol, Methyldopa, Nifedipine, Perinatal Death, Placenta, Pre-Eclampsia, Pregnancy, Pregnancy Outcome, Pregnant Women, Premature Birth, Primary Prevention, Women

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