Hypertensive Women May Stop Medication While Pregnant

Megan Brooks

October 04, 2018

CHICAGO — Many women with chronic hypertension stop taking their antihypertensive medications when they become pregnant, new data show, although it's not clear why and whether this is appropriate, the researchers say.

Lu Chen

"Hypertension is a known risk factor for maternal and fetal morbidity and mortality," Lu Chen, MD, PhD, Kaiser Permanente Washington Health Research Institute, Seattle, told theheart.org | Medscape Cardiology.

"In our study, we observed that many women who were receiving medications for chronic hypertension before pregnancy never filled any antihypertensive medications during pregnancy. We saw this happen even for women with evidence of poorly controlled blood pressure before this pregnancy," said Chen.

She presented the study during the American Heart Association Joint Hypertension 2018 Scientific Sessions.

Safety Concerns?

In the United States, about 1.3 million women of reproductive age take antihypertensive medications. However, some of these medications are considered unsafe during pregnancy, Chen and her colleagues note in their meeting abstract.

For this analysis, they evaluated the burden of switching and stopping medications during pregnancy among women receiving treatment for chronic hypertension.

In three Kaiser Permanente regions, they identified a cohort of 5782 hypertensive women who received antihypertensive medications in the 120 days before becoming pregnant and who gave birth to a single infant between 2005 and 2014. They followed the women's use of antihypertensive medication from 120 days before pregnancy through delivery.

Prior to pregnancy, the most commonly used antihypertensive drug classes were thiazide diuretics (41%), beta blockers (27%) and angiotensin-converting-enzyme (ACE) inhibitors or angiotensin-receptor blockers (ARBs; 24%).

The predominant medications used during pregnancy were labetalol, a bet blocker (37%), and methyldopa, an alpha-2 adrenergic receptor agonist (28%). During pregnancy, 1037 women (18%) had no antihypertensive medication fills.

Women taking an ACE inhibitor/ARB or thiazide diuretic before pregnancy were the most likely to have no medication fills during pregnancy (23% and 20%, respectively).

Of the 881 women (15%) who had at least one measurement of severe high blood pressure (systolic BP ≥160 mm Hg or diastolic BP ≥110 mm Hg) before pregnancy, 132 (15%) filled no medications during their pregnancy.

Reasons for Stopping Unclear

The researchers say more study is needed to understand the impact of antihypertensive treatment interruptions on pregnancy outcomes and women's long-term health.

"Our study did not ask women about their reasons for stopping or switching medication," said Chen. "However, we speculate that women may be worried that these medications may not be safe for the baby, because many medications have not been studied extensively in pregnant women. This can lead women to stop treatment," said Chen.

It's also not possible to tell from the data whether or not stopping or switching antihypertensive drug therapy was appropriate or not.

"We do not know if women who stopped treatment had worse outcomes than women who stayed on medications," Chen added. However, "we are currently planning analyses to examine whether stopping or switching medication may be associated with risks of adverse pregnancy outcomes."

Reached for comment, Diana S. Wolfe, MD, Division of Maternal Fetal Medicine, Montefiore Health System, Bronx, New York, said, "There is a lot of misunderstanding as to what is safe in pregnancy and what is not, although there are very few medications that you absolutely can't use."

"It is very common that pregnant patients come for their first prenatal visit and, whether they were on psychiatric medications or medications for various chronic conditions, often either the patient will self-discontinue or their provider will advise them to discontinue their medication until they see their obstetrician," said Wolfe, who specializes in caring for pregnant women with cardiac risk factors in Montefiore's joint cardiology/ob-gyn program.

She also noted that, "during the second trimester of pregnancy there is a physiologic drop in a woman's blood pressure and that is more of a reason to hold the medication because you don't want the blood pressure to be too low. But you also don't want the blood pressure to be too high in pregnancy.

"Very high blood pressure can cause growth restriction, placental abnormalities, and fetal demise," she added. "I would never advise patients to abruptly stop their medication, but rather make sure the patient is referred promptly to the appropriate medical doctor," said Wolfe.

The study had no commercial funding. Chen and Wolfe have no relevant financial relationships.

Joint Hypertension 2018 Scientific Sessions (HYP): Poster 181. Presented September 6, 2018.

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