High blood pressure rates among pregnant women have soared in the past few decades, based on a study of more than 151 million U.S. women who gave birth between 1970 and 2010. An estimated 70 million U.S. women and nearly 700 million women worldwide have high blood pressure, largely due to modifiable factors like obesity, diet and lifestyle. Using a national registry from the Centers for Disease Control and Prevention, this study looked at delivery-related hospitalizations in 151.5 million women over a 40–year period. It included women aged 15–49 years who gave birth at U.S. hospitals between 1970 and 2020.
The goal of the analysis was to explore how common pre-existing high blood pressure is among pregnant women and how rates have changed over the years. Findings were published in Circulation and show a steady rise in maternal hypertension rates, as well as a drastic health disparity between black and white women.
According to authors, hypertension is a leading cause of death in pregnant women and complicates up to 15% of all pregnancies. As high blood pressure rates continue to grow, experts worry about the effects on maternal health, especially among black women who face greater risk for hypertension.
Overall, the study showed that chronic high blood pressure affected less than one percent of all pregnant women throughout the study period. However, the rate of hypertension increased by an average of 6% each year from 1970–2010. Researchers also found that black women were more than twice as likely to have high blood pressure than white women.
So how do experts explain these changing trends? Based on their analysis, the rise in maternal hypertension was not due to obesity or smoking, both of which significantly increase risk for high blood pressure. Rather, researchers found that risk for hypertension increased sharply with age. In other words, as the average age of pregnant women steadily increased over the years, so did rates of chronic high blood pressure.
Authors note that based on study design, they can’t account for all potential factors that could influence changes in hypertension rates. However, the strengths of the study include the large, diverse population and the long 40–year study period.
Ultimately, findings highlight the need for high blood pressure prevention and treatment among women in the United States, according to authors. Experts hope that reducing these rates, especially in women of childbearing age, can help reduce pregnancy-related complications and improve overall health.