New findings on treating hypertension in pregnancy

A study led by Dr. Sascha Dublin finds similar outcomes for 3 hypertension medications, filling an evidence gap

Hypertension (high blood pressure) is one of the leading causes of maternal mortality in the United States and can be a serious health concern for pregnant women. About 140,000 pregnant women take medication for hypertension each year in the U.S., but fewer than 3,000 women have been studied in randomized clinical trials comparing the outcomes for different medications. This leaves physicians and patients with very little evidence to rely on when deciding between treatment options.

In a new paper published in PLOS ONE, a team of investigators from Kaiser Permanente and the University of Washington present important findings that can help guide care for pregnant women experiencing hypertensive disorders. Their study, led by Kaiser Permanente Washington Health Research Institute Senior Investigator Sascha Dublin, MD, PhD, analyzed 6,346 deliveries in the Kaiser Permanente health care system in Washington, Southern California, and Northern California — regions that serve about 8 million people. The findings showed that the risks of many maternal and neonatal outcomes were very similar for the 3 most commonly used medications: labetalol, methyldopa, and nifedipine. However, compared to labetalol, methyldopa use was associated with significantly lower risk of an infant being born small for their gestational age.

 Prior to this study, Dr. Dublin explained, most evidence for the health impacts of these drugs came from small randomized clinical trials with methods that were not directly comparable to each other. Many of those studies were conducted outside the U.S. and looked at different drugs.

“Women have tremendous questions about the impact of a drug during pregnancy,” she said. “The body changes a lot during pregnancy, and it’s very important to study the effects of these treatments on a pregnant person and the health of the fetus.”

The findings could help reassure pregnant women weighing their medication options and allow physicians to make better informed decisions on treatment, Dublin said. A recent paper in the New England Journal of Medicine provided strong evidence for treating hypertension in pregnancy earlier, when blood pressure levels have not risen to the higher levels that are recommended as the threshold for treatment in current U.S. guidelines. This means that, in the future, a larger number of pregnant women may be receiving medication for hypertension, making it even more crucial to have good information about the health impacts of different treatment options.

There is often concern that hypertension medication might stunt the growth of a fetus. The study done by Dublin and colleagues found that one medication, methyldopa, had significantly better outcomes for infant growth compared to labetalol. Current U.S. guidelines recommend labetalol and nifedipine above other medications and state that methyldopa is less preferred because of possible lower effectiveness and adverse effects, despite little evidence supporting this prioritization. The new findings point to the value of reconsidering methyldopa as a treatment — particularly in cases where infant growth is a major concern — and providing more thorough information on the 2 drugs for both physicians and patients.

The investigators looked at many different outcomes, including babies being born small for their gestational age, preterm delivery, neonatal intensive care admission, preeclampsia, maternal intensive care admission, and stillbirth or termination at 20 weeks or later. Their results did not change when the study population was limited to women with chronic hypertension or when women with pregestational diabetes were excluded.

The study results reinforced the severe impacts of having hypertension in pregnancy, finding that rates of poor outcomes were high even among women getting prenatal care and taking medication.

“Our findings are from women who had access to health care and were treated for hypertension,” said Dublin. “What about similar women who are too scared to take medication, don’t have access to treatment, or miss doses? The rates of bad outcomes may be even higher. These statistics really drive home the importance of understanding and applying the best possible evidence for treating hypertension and addressing patient concerns.”

By Amelia Apfel