The number of pregnant women who develop hypertension during the first 20 weeks of pregnancy has spiked in the U.S. since 1979, especially among black women, with advanced maternal age contributing to this upward trend, say researchers writing in Hypertension this month.
Led by Cande V. Ananth, Ph.D., Rutgers Robert Wood Johnson Medical School in New Brunswick, New Jersey, this was a population-based cross-sectional analysis that included 151 million women who were admitted to the hospital with delivery-related complications between 1970 to 2010 in the United States. Researchers reported a “substantial increase in chronic hypertension rates by age and period and an over 2-fold race disparity in chronic hypertension rates.”
The analysis included women aged 15 to 49 years. Hypertension was defined as blood pressure of 140/90 mm Hg before becoming pregnant or during the first 20 weeks of pregnancy. Overall, 0.63 percent of the women experienced chronic hypertension during their pregnancy, with over a two-fold higher rate among black (1.24 percent) than white (0.53 percent) women. The rate of chronic hypertension increased steadily with advancing maternal age and year of delivery, from 0.11 percent in 1970 to 1.52 percent in 2010, representing a 13-fold increase. Chronic hypertension during pregnancy increased on average by 6 percent every year since 1979, with white women showing a 7 percent increase versus a 4 percent increase in black women each year. After adjusting for obesity and smoking rates, the researchers determined that these factors did not influence the upward trend of chronic hypertension during pregnancy.
“Since more women are electing to postpone their first pregnancies, and advanced maternal age is strongly associated with chronic high blood pressure, women should be aware of the risks associated with having high blood pressure during pregnancy,” the authors wrote.
Chronic hypertension complicates around 5 percent of pregnancies. It is associated with increased risks of perinatal and neonatal mortality and morbidity and maternal outcomes including preeclampsia, stroke, heart failure, cardiomyopathy or kidney failure and death among other risks.
The prevalence of chronic hypertension may be increasing in the U.S. due to advanced maternal age and increases in such risk factors as pregestational diabetes, smoking, being overweight, metabolic syndrome and multifetal pregnancy. Black women are at an increased risk of developing chronic hypertension compared with white women.
Cande V. Ananth, Christina M. Duzyj, Stacy Yadava, et al. “Changes in the Prevalence of Chronic Hypertension in Pregnancy, United States, 1970 to 2010.” Hypertension. Sept 9, 2019. DOI: 10.1161/HYPERTENSIONAHA.119.12968