They studied 85,139 pregnant women enrolled in the Danish National Birth Cohort, comparing lifestyle data during pregnancy with the relative and absolute risk of preeclampsia.
Women with high levels of physical activity – 270 minutes per week to 419 minutes per week, and 420 minutes per week or more – were associated with increased risks of severe preeclampsia, although the absolute risks were still small. Moderate to low exercise levels showed no association with severe preeclampsia.
The authors said: ‘Recommendations have been issued in several countries that pregnant women should exercise at least 30 minutes each day. In our study, we were unable to substantiate that physical activity in early pregnancy has a protective effect against preeclampsia.
‘Leisure time exercise, in amounts that were only slightly higher than the recommended amount, seemed even to be associated with an increased risk of severe types of pre-eclampsia.
The study is published online in BJOG: An International Journal of Obstetrics and Gynaecology.