Managing chronic hypertension through impactful research

Managing chronic hypertension through impactful research | Image Credit: © interstid - © interstid - stock.adobe.com.

One of the areas that excited me about going into obstetrics and gynecology was the ability to impact the field—to create the evidence for practice. There are so many areas where we lack evidence to direct our care. One of these is the management of chronic hypertension. Chronic hypertension impacts nearly 2% of pregnancies, resulting in both adverse maternal and infant outcomes, as it is associated with an increased risk of medically indicated preterm birth, preeclampsia, acute kidney injury, placental abruption, small-for-gestational-age infants, and maternal and perinatal deaths.

Prior to the publication of the CHAP trial, there had been recognition of the importance of treating severe chronic hypertension in pregnancy (blood pressure [BP], ≥ 160/110 mm Hg) to reduce the risk of maternal death and cardiovascular morbidities such as stroke and heart attack, similar to nonpregnant patients. We had limited guidance or understanding of management for mild hypertension in most patients, specifically whether controlling maternal BP to goals recommended in nonpregnant patients. Would it improve outcomes? Would it worsen them? Would it impact the fetus positively or negatively?

Alan Tita, MD, PhD, and the CHAP trial consortium addressed these questions. The goal of the trial was to evaluate antihypertensive therapy compared with no treatment (unless severe BPs occurred) among pregnant women with mild chronic hypertension. Published in the New England Journal of Medicine, Tita and colleagues showed that antihypertensive therapy for mild hypertension not only does not harm pregnancy outcomes but also improves them.¹

The CHAP trial was an open-label, multicenter, randomized trial screening 29,772 patients and enrolling 2408 pregnant women at 61 centers with singleton gestations and mild chronic hypertension prior to 23 weeks of gestation. They were randomly assigned to receive antihypertensive therapy or no treatment unless severe hypertension developed. They found that treating maternal BP to a threshold of 140/90 mmHg in women with chronic hypertension improved the primary outcome, including severe preeclampsia, preterm birth before 35 weeks, abruption, and perinatal death, with no change in birth weight less than the tenth percentile for gestational age.¹ 

Based on these findings, the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine recommend using 140/90mm Hgas the threshold for initiation or titration of medical therapy for chronic hypertension in pregnancy, rather than the previously recommended threshold of 160/110mm Hg. In this issue, Tita and colleagues bring the results of this trial to the Contemporary OB/GYN audience.

Reference

Tita AT, Szychowski JM, Boggess K, et al. Treatment for mild chronic hypertension during pregnancy. N Engl J Med. 2022;386(19):1781-1792. doi:10.1056/NEJMoa2201295