To treat or not to treat pregnant women with mild chronic hypertension: that has been a longtime concern and unanswered question for Joseph Bell, MD, Section Chief of Maternal Fetal Medicine for St. Luke’s University Health Network (SLUHN), and his obstetrician-gynecologist colleagues in the United States.
They have been concerned that, while blood pressure medications would protect the mothers from serious cardiovascular complications such as stroke, and pregnancy-related complications, such as preeclampsia and premature delivery, the drugs might adversely affect fetal growth by reducing blood flow to the baby. Current guidelines in the U.S. do not recommend routine medical treatment of mild chronic hypertension during pregnancy.
The answer to the question, now, is yes, that standard antihypertensive medications are effective for protecting mothers’ health and are safe for their babies. The conclusion came on April 2 in the authoritative article, “Treatment for Mild Chronic Hypertension in Pregnancy,” published in the New England Journal of Medicine (NEJM). The article reports on the outcomes of a six-year research study involving over 2,400 women and 61 research centers throughout the U.S., including Dr. Bell and St. Luke’s. Dr. Bell’s Maternal Fetal Medicine group enrolled the seventh largest number of patients of those centers in the U.S. participating in the study.
Half of the study subjects were randomized to treatment with standard antihypertensive medication, while the other half was randomized to no medical treatment, which is the current standard of care, unless or until blood pressures reached a severe range. The study conclusively found that the group randomized to treatment experienced better pregnancy outcomes than the group randomized to no treatment.
Erin Cudworth, who had mild chronic hypertension, enrolled in the study and was randomized to have no treatment. But at 34 weeks, she developed severe hypertension and was started on antihypertensive medication.
“I was totally fine on meds,” says Cudworth, a nurse in St. Luke’s in Labor and Delivery unit at the St. Luke’s Anderson Campus. She delivered a healthy 5 lb., 12 oz, 19-inch baby girl, Gracelynn, 18 months ago, at 37 weeks gestation following a diagnosis of preeclampsia.
She’s pregnant with her second child and is pleased that the research outcomes are favorable for medication treatment, information that she’ll also be sharing with the couples she teaches in prenatal classes at St. Luke’s
Dr. Bell, the region’s only contributing researcher and author in this innovative study, “Chronic Hypertension in Pregnancy (CHAP),” and article, says, “This groundbreaking study will now change how pregnant women with mild, chronic high blood pressure are treated.”
“For many years, we haven’t known how to most effectively and safely treat mild chronic hypertension in pregnancy, but the conclusions from this study now give us much-needed evidence and guidance for optimal care,” says Dr. Bell, who also served at the research’s principal investigator at St. Luke’s.
“Knowing that medical management of this common condition is effective and safe is going to change our approach in a significant way because of this research, and this will benefit many women and their babies.”
Nationally, over 2% of pregnant women are diagnosed with chronic hypertension, with 70% of them falling in the mild category. In the U.S., a disproportionate number of Black women are affected by chronic hypertension during pregnancy.
“So, Black women, in particular, are going to benefit from this newly recommended management approach, and this will be a step forward in using quality improvement and safety science to eliminate pregnancy-related racial health inequalities,” adds Dr. Bell. Of the more than 2,400 pregnant patients enrolled in the CHAP study, almost 50% were Black women.
The results of the CHAP study were presented on Saturday (April 2) at the American Cardiology Conference in Washington, DC, by Alan Tita, MD, PhD, of the University of Alabama Birmingham, who is the national principal investigator for the study.
“Treatment for Mild Chronic Hypertension in Pregnancy” was published in NEJM at that time and concluded: “In pregnant women with mild chronic hypertension, a strategy of targeting a blood pressure of less than 140/90 mm Hg was associated with better pregnancy outcomes than a strategy of reserving treatment only for severe hypertension, with no increase in the risk of small-for-gestational-age birth weight.” Severe hypertension is defined as a blood pressure of 160/105 mm Hg or greater.
Previous research on this topic has been disappointing due to small numbers of enrolled subjects or inconclusive data that resulted, says Dr. Bell.
“But the results of the CHAP study are conclusive and game-changing: they reinforce that this is the right and safe way to treat these patients without harming their babies. We’re now confident of that conclusion.”