Tight Hypertension Control Does Not Lower Pregnancy Complication Risk

Tight blood pressure (BP) control in pregnant women with milder forms of hypertension does not significantly change the risk of pregnancy-related complications compared with less-tight BP control, but does lower the risk of developing severe hypertension, according to a new study published in The New England Journal of Medicine. (2015:372:407-417).

For the Control of Hypertension in Pregnancy Study (CHIPS)—one of the larger randomized, controlled trials on the subject—investigators led by Laura A. Magee, MD, of the BC Women’s Hospital and Health Centre in Vancouver, studied maternal and fetal outcomes of 987 pregnant women in 16 countries with non-severe, non-proteinuric hypertension (74.6%) or gestational hypertension. All participants were in their second trimester of pregnancy, between 14 and 34 weeks.

The women were randomly assigned to less-tight control (target diastolic pressure 100 mm Hg) or tight control (target diastolic pressure 85 mm Hg). Their starting diastolic pressures were 90 to 105 mm Hg (or 85 to 105 mm Hg if taking blood pressure medications). Two-thirds of the women on antihypertensive medication took labetalol. Women with pre-existing diabetes or renal disease were excluded.

International guidelines have recommended treatment goals consistent with either tight or less-tight control for such women.

The researchers found no significant differences in the risk of pregnancy loss, high-level neonatal care (for 2 days or more), or serious maternal complications post partum, despite blood pressure that was 5.8/4.6 mm Hg higher on average in the less-tight control group. (Most serious maternal complications occurred among women with preeclampsia.)

However, severe hypertension of 160/110 mm Hg or higher developed in 40.6% of the women with less-tight control versus 27.5% of women with tight control. If uncontrolled, severe hypertension can lead to stroke during and after pregnancy.

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