High blood pressure treatment during pregnancy may be safe for many women, according to a new American Heart Association scientific statement that was published today in the journal Hypertension.
The statement says that treating high blood pressure during pregnancy may reduce the risk of severe hypertension in the mother without increasing the risk for the fetus and the baby.
In this statement, experts in obstetrics and gynecology, maternal-fetal medicine, cardiology, nephrology, hypertension, and internal medicine looked at high blood pressure during pregnancy, such as gestational hypertension and preeclampsia/eclampsia.
According to the current American Heart Association data, hypertension during pregnancy is the second largest cause of maternal death globally, with a systolic pressure (the top number in a blood pressure reading) of 140 mm Hg or greater. Severe cases are linked to an elevated risk of cardiovascular issues for women during and after delivery, as well as for years afterward. Preterm delivery, small for gestational age, and low birthweight were all increased hazards for the offspring when hypertension was present during pregnancy. Hypertension during pregnancy is becoming more common around the world, and research shows that it disproportionately affects women of various racial and ethnic backgrounds in the United States, notably those who are Black, American Indian, or Alaskan Native.
Treatment during pregnancy aims to prevent severe hypertension and early birth, giving the fetus enough time to mature before delivery.
“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,” says Chair of the statement writing group Vesna D. Garovic, M.D., Ph.D., a 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.”
According to the statement, the United States has one of the highest rates of hypertensive-related maternal death among high-income countries. Cardiovascular disease, which includes stroke and heart failure, now accounts for up to half of all maternal deaths in the United States, and hospitalizations for pregnancy-related strokes climbed by more than 60% from 1994 to 2011. According to the American Heart Association, preeclampsia occurs when hypertension during pregnancy is accompanied by signs of liver or kidney problems, such as protein in the urine. It affects 5% to 7% of pregnancies and is responsible for more than 70,000 maternal deaths and 500,000 fetal deaths each 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,” Garovic adds.
While the definition of hypertension for the general population is established at 130/80 mm Hg according to 2017 in the American College of Cardiology (ACC)/ American Heart Association (AHA) Guideline for the Prevention, Detection, Evaluation and Management of High Blood Pressure in Adults, most guidelines worldwide define hypertension during pregnancy as 140/90 mm Hg.
There is a lack of consensus about when to start hypertension treatment during pregnancy because of concerns about how medications may impact 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).
The new statement points to evidence that blood pressure-lowering therapy for pregnancy hypertension significantly reduces the incidence of severe hypertension. Additional research is needed to determine the extent to which treating hypertension at a lower threshold may decrease serious hypertensive complications, namely organ damage and hypertensive emergencies. Reducing severe hypertension may be particularly important in communities that lack resources and expertise to respond to hypertension emergencies, the statement authors write.
“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,” adds Garovic.
So far, the latest research indicates that treating hypertension during pregnancy with blood pressure-lowering medicine does not appear to negatively impact fetal growth or development. Preventing hypertension during pregnancy supports maternal health both during and after pregnancy. It is well known that those who have hypertension during pregnancy are more likely to develop sustained hypertension after pregnancy at a higher rate compared to those whose blood pressure was normal during pregnancy. The statement reinforces recent research that suggests lifestyle changes before and during pregnancy have the potential to improve maternal and fetal outcomes:
- Dietary changes before and during pregnancy can limit weight gain and improve pregnancy outcomes.
- Exercise during pregnancy may reduce gestational hypertension risk by about 30% and preeclampsia risk by about 40%.
The statement also highlights these areas of concern:
- There is emerging evidence that hypertension after delivery (postpartum) may be associated with significant maternal health problems.
- The current science suggests physicians should individualize treatment decisions, considering risk factors and patient preferences.
- The care of women with hypertension during pregnancy is often complex, and a multispecialty team of health care professionals may be beneficial.
“Future clinical trials are needed to address questions about when to begin treatment for high blood pressure during pregnancy,” says Garovic.
“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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