SEATTLE, Oct. 1 (UPI) -- Most sleep studies exclude pregnant women, so little is known about how sleep contributes to increased risks during pregnancy, U.S. researchers say.
Lead author Dr. Michelle Williams of the University of Washington and the Swedish Medical Center in Seattle suggests too much or too little sleep early in pregnancy may be linked to greater risk of pregnancy complications involving high blood pressure such as preeclampsia.
"Both short and long sleep duration in early pregnancy were associated with increased mean third trimester systolic and diastolic blood pressure values," Williams says in a statement. "Moving forward, large-scale sleep studies should include pregnancy cohorts so that healthcare providers and mothers-to-be can more fully appreciate the health risks of insufficient sleep."
Williams and colleagues studied 1,272 healthy, pregnant women who completed a structured interview at about 14 weeks gestation.
About 20 percent reported a sleep duration of 9 hours per night -- considered "normal" because prior research indicates pregnant women tend towards longer sleep duration patterns. About 55 percent of women reported sleeping 7 to 8 hours, 14 percent slept 6 hours or less and about 10 percent slept 10 hours or more.
The study is published in the journal Sleep.