Elevated blood pressure means that your blood pressure is higher than normal but not high enough to lead to a diagnosis of high blood pressure (hypertension). The good news is that lifestyle changes, such as eating a healthy diet, exercising, and weight management, can have positive effects on blood pressure and reproductive health. The NIH study, published in April 2018 in Hypertension, was led by Carrie J. Nobles, PhD, a postdoctoral fellow at the Eunice Kennedy Shriver National Institute of Child Health and Human Development in Bethesda, Maryland. In total, 1,228 U.S. women who were trying to get pregnant and had at least one prior miscarriage were included in the study. Approximately 797 women got pregnant and 188, or 24 percent, had a miscarriage. The risk of miscarriage increased 18 percent per every 10 millimeters of mercury (mmHg) increase in diastolic blood pressure (the bottom number of a blood pressure reading). “It is important to stress that our findings are observational and therefore cannot be used to demonstrate cause and effect,” said Dr. Nobles. “What they do suggest, however, is that women who have elevated preconception blood pressure are at a higher risk of pregnancy loss, and more research is needed to determine whether lifestyle interventions that are associated with maintaining healthy blood pressure may reduce risk of pregnancy loss.”
Details About the Study and the Participants
To be eligible for the study, women had to be 18–40 years old, actively trying to get pregnant, with a history of one to two prior pregnancy losses and up to two prior live births. Women also needed to have regular menstrual cycles of 21 to 42 days, no history of infertility, no major medical problems, and be able to take aspirin. Women in the study were randomized to receive a daily dose of 81 milligrams (mg) of aspirin and folic acid, or a placebo (no active drug) plus folic acid. They continued to take the aspirin or placebo for up to six menstrual cycles while trying to get pregnant, or throughout pregnancy if they were able to conceive. Blood pressure before pregnancy was measured at the time of enrollment. Blood pressure measurements were taken also during routine prenatal visits at 4, 8, 12, 16, 20, 28, and 36 weeks gestation. However, only the blood pressure measurement taken at 4 weeks gestation was included in analyses since the majority of miscarriages occur early in pregnancy. Women in the study were mostly white (95 percent), college educated (86 percent), and married (92 percent). The average age was 28.7 and most of the women were overweight. Although elevated blood pressure before pregnancy was linked to increased risk of miscarriage, elevated blood pressure was not linked to a woman’s probability of becoming pregnant in a single menstrual cycle (fecundability) or live births — the two other study outcomes of interest. Also, this study included women that had already had at least one prior miscarriage. As such, it is unknown if the relationship between elevated prepregnancy blood pressure and increased risk of miscarriage holds for women without a prior history of miscarriage.
What This Means for Women Trying to Get Pregnant or Already Pregnant
Regular blood pressure monitoring is necessary during pregnancy. It’s also important after pregnancy to ensure that a diagnosis of hypertension does not go undetected and untreated. “I believe all women with elevated blood pressure during pregnancy should see a cardiologist,” says Suzanne Steinbaum, DO, director of women’s cardiovascular prevention, health, and wellness at Mount Sinai Hospital in New York City and spokesperson for the American Heart Association’s Go Red For Women. “Pregnancy is a metabolic stress test that gives us a warning about the risk for heart disease.” Dr. Steinbaum notes that it’s important for women to partner with physicians to reach lifestyle goals. For example, incorporating a heart healthy diet that is low in salt and filled with high-nutrient foods such as fruits, vegetables, and omega-3 fatty acids is key. Watching weight gain during pregnancy is also important and should be discussed with your obstetrician. Additionally, walking and gentle exercise are good ways to stay physically active during pregnancy. “Heart disease does not manifest late in life, as demonstrated by this study,” says Steinbaum. “It’s something that we need to be aware of throughout a woman’s life, and screening and treatment need to be implemented as early as possible.”
