Problems With First Pregnancy Can Signal High Blood Pressure Later in Life

A preterm birth or preeclampsia can put a mother at twice the risk of high blood pressure in the years after her baby arrives, according to a new study funded largely by the National Institutes of Health (NIH).

The study’s authors say their findings show that physicians must do more to understand women’s health histories, both to prevent problems during pregnancy and to identify patients at risk for heart attacks and strokes.

The Nulliparous Pregnancy Outcomes Study Monitoring Mothers-to-be Heart Health Study (nuMom2b), published in the Journal of the American Heart Association, followed 4484 women for 2 to 7 years after their pregnancy (mean 3.2 years). Of the group, 1017 (22.7%) had problems identified during pregnancy defined as hypertensive disorders, which included preterm birth, stillbirth, and small-for-gestational age birth. Women who did not experience these issues served as a control group. Risk ratios were adjusted for age, smoking status, body mass index (BMI), race and ethnicity, and type of insurance.

“We used to think it took years and years to develop high blood pressure,” study author David Haas, MD, a professor of obstetrics and gynecology at Indiana University School of Medicine said in a statement. “We found it can occur much sooner than expected—in as little as 3 years.”

The women had an average age of 27, which is about the average age of women giving birth for the first time nationally, according to data from the CDC. Of the group, 62% are white, 14% are black, 16% are Hispanic, 3% are Asian, and 5% reported “other” as their ethnicity. Researchers found that 31% of the women with at least 1 adverse outcome in their first pregnancy developed hypertension, compared with 17% in the group that did not have complications.

Avoiding hypertension after giving birth may be more challenging in the United States because more women are waiting until they are older for their first pregnancy, according to CDC. Complications are known to increase with the mother’s age. Also, slightly more than half of women giving birth were overweight or obese in 2014, which also increases the risk of pregnancy complications, according to a separate CDC report.

Women should be mindful to get prenatal care as early as possible and to alert their obstetrician about existing health conditions, Haas said. Current recommendations for women considering pregnancy call for paying attention to nutrition and exercise in the months before becoming pregnant, including aiming for a BMI between 19 and 24 kg/m² and increasing levels of key nutrients, including folic acid.

Results. The overall incidence of hypertension was 5.4% (95% CI, 4.7% to 6.1%). Women with adverse pregnancy outcomes had a higher adjusted risk of hypertension (relative risk [RR] 2.4, 95% CI, 1.8 to 3.1). This held for individual adverse outcomes: any hypertensive disorder, RR 2.7, 95% CI, 2.0-3.6; preeclampsia, RR 2.8, 95% CI, 2.0-4.0; and preterm birth, RR 2.7, 95% CI, 1.9-3.8).

Women who gave birth early and had hypertensive disorders of pregnancy had the highest risk of hypertension in the years after pregnancy, with a RR of 4.3, 95% CI, 2.7-6.7).

Reference

Haas DM, Parker CB, Marsh DJ, et al. Association of adverse pregnancy outcomes with hypertension 2 to 7 years postpartum. J Am Heart Assoc. 2019; e013092. doi:10.1161/JAHA.119.013092.