Rochester, MN—With a new scientific statement noting that treatment for high blood pressure during pregnancy appears safe for many women and might reduce maternal risk for severe hypertension without increasing fetal and neonatal risks, pharmacists can dispense the medications with more assurance.

With the new American Heart Association (AHA) scientific statement, published recently in the journal Hypertension, experts in obstetrics and gynecology, maternal-fetal medicine, cardiology, nephrology, hypertension, and internal medicine reviewed and analyzed research on high blood pressure during pregnancy. The review included gestational hypertension and preeclampsia/eclampsia.

AHA statistics suggest that hypertension during pregnancy, which is defined as a systolic pressure of 140 mm Hg or higher, is the second leading cause of maternal death worldwide. The implications are very serious, and that:

• Severe cases are associated with increased risks of cardiovascular complications for mothers immediately or soon after delivery, and for years after pregnancy.
• Hypertension during pregnancy increased the risks for newborn complications, including preterm delivery, small for gestational age, and low birthweight.
• Rates of hypertension during pregnancy are increasing globally.

The group notes that the condition disproportionately affects women who are from diverse racial and ethnic backgrounds in the United States, especially those who are Black, American Indian, or Alaskan Native.

"For decades, the benefits of blood pressure treatment for pregnant women were unclear. And there were concerns about fetal well-being from exposure to antihypertensive medications," said chair of the statement writing group Vesna D. Garovic, MD, PhD, professor of medicine, chair of the Division of Nephrology and Hypertension with a joint appointment in the Department of Obstetrics and Gynecology at Mayo Clinic in Rochester, Minnesota. "Through our comprehensive review of the existing literature, it is reassuring to see emerging evidence that treating high blood pressure during pregnancy is safe and effective and may be beneficial at lower thresholds than previously thought. Now, we have the current statement focused on hypertension during pregnancy to help inform optimal treatment and future research."

This allows clinicians to treat the condition during pregnancy to prevent early delivery and allow the fetus time to mature before delivery.

Among high-income countries, the U.S. has one of the highest hypertensive-related maternal mortality rates, with cardiovascular disease, which includes stroke and heart failure, now making up as much as half of all maternal deaths here. In addition, pregnancy-related stroke hospitalizations increased more than 60% from 1994 to 2011.

The AHA also notes that preeclampsia, which occurs when hypertension during pregnancy and is accompanied by signs of liver or kidney problems such as protein in the urine, affects 5% to 7% of pregnancies; it is responsible for more than 70,000 maternal deaths and 500,000 fetal deaths worldwide every year.

Given the rising number of cases of hypertension during pregnancy, together with hypertension-related complications, the problem has become a public health crisis, particularly among women from racially and ethnically diverse backgrounds," Dr. Garovic said.

In most guidelines worldwide, the definition of hypertension during pregnancy—blood pressure of 140/90 mm Hg or higher—differs from that for the general population, set at 130/80 mm Hg.

Furthermore, consensus is lacking on when to initiate treatment during pregnancy due to concerns about how medications could affect the fetus. Several health advocacy groups recommend beginning treatment when blood pressure measures during pregnancy are from 140/90 mm Hg (Canadian guidelines) to 160/110 mm Hg (U.S. guidelines), according to the AHA.

The new statement provides evidence that blood pressure—lowering therapy for pregnancy hypertension significantly reduces the incidence of severe hypertension. It also notes that additional research will be required to determine the extent to which treating hypertension at a lower threshold can decrease serious hypertensive complications, such as organ damage and hypertensive emergencies. In fact, authors point out that reducing severe hypertension might be especially critical for communities that lack resources and expertise to respond to hypertension emergencies.

"Future studies should address whether lowering the threshold for treating hypertension during pregnancy might allow for safe and timely blood pressure control and avoid a rushed delivery because of uncontrolled hypertension," Dr. Garovic suggested.

The latest research indicates that treating hypertension during pregnancy with blood pressure—lowering medicine does not appear to negatively impact fetal growth or development. The statement, meanwhile, raises concerns about postpartum hypertension.

"Future clinical trials are needed to address questions about when to begin treatment for high blood pressure during pregnancy," Dr. Garovic stated. "Also, close collaboration between the American Heart Association and American College of Obstetricians and Gynecologists will be instrumental in optimizing diagnosis and treatment of hypertension during pregnancy and in improving immediate and long-term outcomes for many women who develop hypertension during pregnancy."

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