Pregnancy Duration and Hypertension Risk: What's the Connection?

This transcript has been edited for clarity.

Hello. This is Dr JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women's Hospital. I'd like to talk with you about an important study recently published in JAMA Cardiology on the subject of preterm delivery and long-term risk for hypertension in women. This is the largest study ever done on this subject, and it leveraged nationwide birth register data from Sweden, which included more than 2.1 million women, more than 4 million births dating back to 1973, and more than 40 years of follow-up.

They found that a preterm delivery (birth at less than 37 weeks' gestation) was a strong predictor of increased risk for hypertension in women compared with a full-term birth (39-41 weeks' gestation). Overall, there was a 67% increased risk for new-onset hypertension in this study, and the shorter the pregnancy, the greater the increase in risk. So women who had a pregnancy duration of 22-27 weeks had more than a doubling in the risk for new-onset hypertension. Women with a pregnancy duration of 28-33 weeks had an 85% increased risk for hypertension. Women with a pregnancy duration of 34-36 weeks had a 55% higher risk for hypertension and an elevation in hypertension.