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HypertensionMay 2022Summary reviewed August 2026

Blood Pressure Pills Cut Pregnancy Complications by 18% in Women with High Blood Pressure

In a study of 2,408 pregnant women with mild high blood pressure, those who took medication to keep their blood pressure under 140/90 had fewer serious complications than those who only took medication when their pressure got dangerously high. The treatment lowered the risk of preeclampsia, early delivery, and placental problems without harming the baby's growth.

What the trial was testing

The CHAP enrolled 2,408 patients with hypertension. The study was sponsored by University of Alabama at Birmingham and tracked outcomes across the full group of patients who matched the trial's eligibility profile.

It was long-term safety (phase 4). Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.

What the results showed

Treating mild high blood pressure during pregnancy reduced serious complications by 18%.

The New England journal of medicine · 2022 · NCT02299414

These findings — that fewer women had preeclampsia, early delivery, or placental problems when treated early — were published in the The New England journal of medicine and represent the headline result of the study.

Researchers tracked outcomes across 2,408 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.

What this means for patients

For patients with hypertension, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.

What you can do now

If you have mild high blood pressure and are pregnant, this study shows that taking medication early — rather than waiting until your pressure gets dangerously high — can protect both you and your baby. The treatment reduced the risk of preeclampsia and early delivery without affecting the baby's size. These medications are FDA-approved and widely used in pregnancy. Talk to your OB about whether starting treatment early is right for you.

Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.