African American pregnant woman reading tabletWomen who develop a dangerous elevation in blood pressure during pregnancy may develop thickened heart tissue soon after delivery, a new study shows.

In the study, women with preeclampsia had an increased risk of left ventricular hypertrophy one month after delivery compared to pregnant women without preeclampsia. The heart problem occurs when the left pumping chamber thickens, making it more difficult for the heart to pump efficiently.

The findings were presented Thursday at the American Heart Association and American Society of Hypertension Joint Scientific Sessions in San Francisco.

The researchers also found that the heart changes were more severe in women who developed preeclampsia before the 34th week of pregnancy.