Hypertension in Pregnancy: New Insights to Reduce CVD

JoAnn E. Manson, MD, DrPH


July 07, 2022

This transcript has been edited for clarity.

Hello. This is Dr JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women's Hospital. I'd like to talk with you about two recent publications that provide insights on the implications of hypertension in pregnancy for the mother's and infant's health. One study sheds light on the treatment of mild chronic hypertension during pregnancy and the other on new-onset hypertension, gestational hypertension, or preeclampsia in relation to a woman's subsequent cardiovascular disease risk.

The first study was published in the New England Journal of Medicine: a randomized clinical trial including more than 2400 women. This was a multicenter trial looking at treatment of nonsevere hypertension in the Chronic Hypertension And Pregnancy Trial (CHAMP). The women were randomized to either receive a medication (most commonly it was labetalol or nifedipine) for hypertension in the range of 140/90 mm Hg to 160/105 mm Hg vs not receiving treatment for a blood pressure in that range. They were all randomized prior to 23 weeks of pregnancy.

This trial showed that the women who were randomized to active treatment with medication did better than the women who were left undertreated for this degree of hypertension. So the treated women had a lower risk for the primary composite of severe preeclampsia, preterm birth, fetal or neonatal death, or other adverse pregnancy outcomes. They had a statistically significant 18% reduction in this composite. They also had a significant reduction of 21% in development of any preeclampsia and a 13% reduction in preterm birth. There were no real safety signals in the trial and no clear evidence of any fetal growth restriction. So overall, the conclusion was that it's advisable to treat blood pressure in this range during pregnancy, and this trial is likely to lead to some changes in clinical guidelines.

The other study was an epidemiologic study published in the Journal of the American College of Cardiology. This is from the Nurses' Health Study II, with more than 60,000 women who had a history of new-onset gestational hypertension or preeclampsia during the first pregnancy and looked at their risk for subsequent cardiovascular disease (CVD) events over a 30-year follow-up period. It demonstrated that having any hypertensive disorder a pregnancy was associated with a 63% increased risk for subsequent CVD. Preeclampsia was associated with a 72% increase in risk and gestational hypertension with a 41% increase in risk. Preeclampsia was especially strongly associated with subsequent coronary heart disease, more than doubling in risk, and gestational hypertension was associated with about a 60% increased risk for subsequent stroke.

What was particularly interesting was that they looked at the extent to which the increased risk for CVD was mediated by traditional risk factors for CVD, such as being diagnosed with hypertension, diabetes, lipid disorders, or having a change in body weight during the follow-up period. They saw that overall, about two thirds of the subsequent cardiovascular events were mediated by these traditional risk factors, and hypertension was a particularly strong mediator — more than 50% mediated by hypertension, about 16% by lipid disorders (high cholesterol), about 10% by subsequent diabetes, and close to one quarter by changes in body weight. So this study strongly suggested that screening, monitoring, and treating these traditional cardiovascular risk factors (in particular treating hypertension) could mitigate some of the excess risk for cardiovascular events occurring after a hypertensive disorder of pregnancy.

Overall, these two studies have really moved the needle in our understanding of hypertension in pregnancy, and the findings hold promise for improving maternal and child health. Thank you so much for your attention. This is JoAnn Manson.

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