According to an NIH-funded study, women who took medication for persistent hypertension in pregnancy had fewer negative pregnancy outcomes.
More than 2,400 pregnant adults participated in the study, which found that those who used medication to drop their blood pressure below 140/90 mm Hg had a lower risk of having a preterm birth or suffering from a major pregnancy complication, such as preeclampsia. Hypertension medication didn't affect fetal growth.
Alan T. N. Tita, M.D., Ph.D., the study's principal investigator and John C. Hauth Endowed Professor of Obstetrics and Gynecology at the University of Alabama at Birmingham Marnix E. Heersink School of Medicine, revealed that treating chronic hypertension during pregnancy "represents a major step forward"
Chronic Hypertension and Pregnancy (CHAP) trial results were presented at the 71st Annual Scientific Session and Expo of the American College of Cardiology on April 2 and published in the New England Journal of Medicine. NHLBI, an NIH division, funded the study.
Diane Reid, M.D., a program officer in the NHLBI's Division of Cardiovascular Sciences, says that early treatment for high blood pressure could help a lot for the thousands of American adults who are at risk for preeclampsia or early births. Chronic hypertension can quadruple the chance of major issues in pregnant women.
Sixty-one U.S. medical facilities recruited pregnant hypertensive patients for CHAP from 2015 to 2021. In this study, hypertension was defined as systolic blood pressure above 140 mm Hg and diastolic blood pressure above 90 mm Hg at the start of the trial. Normal blood pressure for adults is less than 120/80 mm Hg. Participants enrolled before 23 weeks of pregnancy. They were studied during labor and for six weeks after delivery.
Randomly assigned to one of two groups, the 1,208 intervention group individuals were given antihypertensive medication to reduce their blood pressure. The 1,200 individuals in the control arm, however, did not receive blood pressure medication unless their blood pressure exceeded 160/105 mm Hg. 70% of antihypertensive-treated individuals had no major adverse pregnancy outcomes, while 30% had placental abruption, preterm birth at less than 35 weeks, fetal or neonatal death, or severe preeclampsia beyond 20 weeks. 37% of the control group reported a similar unfavorable event. For every 14–15 women who received early hypertension medication, one was spared a serious result, the study found.
Antihypertensive drugs didn't affect neonates' birth weights. Most babies' birthweights were normal across groups. Impaired fetal growth, defined as birth weight below the 10th percentile for newborns of the same gestational age, occurred in 11.2% of medicated babies and 10.4% of control babies.
"The research ensures that treating hypertension during pregnancy is safe and useful," said Dr. Reid. She says the findings will help guide treatment options that have varied due to a lack of evidence on antihypertensive medications' effects on embryonic growth and development. Medical organizations advise avoiding the therapies except in extreme hypertension. The authors say this study should inform clinical guidelines.
Future studies are needed to better understand the usage of hypertension medications during pregnancy, say experts.