A study published this month in the New England Journal of Medicine proves through a large clinical trial that treating high blood pressure—even mild cases—during pregnancy is safe and beneficial for both mother and developing baby. Ochsner Health was a site since 2014 for the study which was led by University of Alabama at Birmingham.

While medical professionals have long agreed that severe high blood pressure during pregnancy should be treated with medications, the medical community has been divided on how to treat mild forms of chronic hypertension in pregnant women. The groundbreaking results of the Chronic Hypertension and Pregnancy trial, or CHAP trial, show evidence-based data that even mild forms of high blood pressure should be treated to improve maternal and fetal health outcomes.

“Chronic hypertension causes serious and life-threatening complications for pregnant women and their babies,” said Alan Tita, MD, PhD, professor of obstetrics and gynecology in the UAB Marnix E. Heersink School of Medicine, principal investigator for the CHAP trial, and lead author of the NEJM paper. “Between 70 and 80% of pregnant women with chronic hypertension fall into the ‘mild’ category where there is not a medical consensus for treatment. In light of these new data, it is important that we reevaluate current recommendations, update practice guidelines and begin treating most — if not all — pregnant women with chronic hypertension with medication.”

Recommendations are already updating. Within three days of the study’s publication, the American College of Obstetricians and Gynecologists issued a statement of intention to update clinical guidance via a Practice Advisory. The Society for Maternal Fetal Medicine also issued a statement that they are reviewing the trial results and will issue revised clinical guidance as appropriate.

“This study will change the way we’ve been treating pregnant mothers with mild hypertension,” said Sherri Longo, MD, Director of Research for Women’s Services at Ochsner Health and one of the study authors. “With this publication, the recommendation is that we don't wait for the severe range before we initiate medical therapy. Mild hypertensive patients should have blood pressures that are controlled.”

The study authors recommend that blood pressure of blood pressure of 140/90 mmHg be the threshold for initiation of medical therapy for chronic hypertension in pregnancy, rather than the previously recommended threshold of blood pressure greater than 160/105 mmHg. The trial demonstrated that by treating women with even mild blood pressure with medications, there was an almost 20% decrease in pregnancy complications such as severe preeclampsia and preterm births before 35 weeks’ gestation.

Ochsner joined CHAP trial at its inception in 2014. More than 70 clinical sites across the United States joined the trial, making it one of the most comprehensive and diverse studies of its kind. Almost 50% of study participants were Black mothers.

“Treating our pregnant women with even mild hypertension will improve their pregnancy outcomes” said Dr. Longo.

Learn more about the clinical trial results and the CHAP consortium at the UAB website.