One in five women of childbearing age has high blood pressure, according to a new study that found few of these women are on a diet that could help them – and their babies – reduce their risk for health problems.

High blood pressure, also known as hypertension, in pregnancy is a leading cause of maternal death. Nearly 40% of maternal deaths from any cause are associated with hypertension.

"We need to have more of a focus on how we teach lifestyle factors to women even before they are considering pregnancy," said Dr. Lara Kovell, an assistant professor of cardiology at the University of Massachusetts Medical School in Worcester who led the study. "This is the time to talk to women about evaluating their diet, looking at their risk factors and trying to get high blood pressure under control."

Kovell presented the preliminary findings at the American Heart Association's Scientific Sessions, which wraps up Monday in Philadelphia. She and her colleagues analyzed data collected on 8,740 women ages 20 to 50 taking part in a national health and nutrition study from 2001 to 2016. They found that 22.4% of the women had high blood pressure.

Researchers scored how healthy the women ate and how much salt they consumed compared to guidelines set out in the Dietary Approaches to Stop Hypertension, or DASH, diet. It is recommended for all adults with high blood pressure

They found that 7% of the women who had high blood pressure were adhering to a DASH-like diet, while 10% of women with normal blood pressure were.

People who follow DASH eat foods low in salt and that contain high levels of nutrients to help lower blood pressure, such potassium, magnesium and calcium. These foods include fresh fruit and vegetables, beans and lentils, and whole grains.

"We have a lot of opportunities to improve the nutrition of American women," said Dr. Lisa Hollier, chief medical officer in obstetrics and gynecology for Texas Children's Health Plan. "This study really highlights the need to take advantage of those opportunities to ensure that women who have a diagnosis of hypertension know that they can lower their blood pressure with the right diet."

High blood pressure occurs when the force of blood flowing through the blood vessels is consistently too high. Managing the extra force causes the heart muscle to become stiff and thick, keeping it from working properly. This, in turn, increases the risk of stroke, heart attack, kidney failure and heart failure.

Women who go into a pregnancy with high blood pressure are at risk of having a baby who has a low birth weight or is born premature.

"I think our findings are a wake-up call for all doctors to be mindful about addressing cardiovascular risks with women," said Kovell. "We don't want women to start taking medications when they are pregnant or thinking about getting pregnant, which makes diet and exercise the best approach to lower blood pressure."

In the U.S., cardiovascular disease is the leading cause of death during and after pregnancy. In May, the American College of Obstetricians and Gynecologists released new guidelines on managing heart disease in women before, during and after pregnancy.

Hollier, ACOG's past president, said the new study "highlights the critical importance of OB-GYNs and other health care providers working together to help women understand – before and after a pregnancy – options they have to reduce their risk for cardiovascular disease."

Find more news from Scientific Sessions.

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