(HealthDay News) — Pregnant women should not ride roller coasters or other jarring rides at the amusement park, says the American Pregnancy Association.

The rapid starts and stops and jerky motions that characterize these rides can lead to premature separation of the placenta, the group says. Premature separation has occurred among many women in car accidents.

Currently, there are no studies documenting the safety of thrill rides for pregnant women. But the American Pregnancy Association suggests playing it safe, recommending that pregnant women avoid such rides altogether.