According to a new study of over 90,000 pregnant women in Denmark, has cleared up that women who did jogging or play racket sports and ball games early in pregnancy were at high risk of losing their child.

The scientists discovered that women who worked out more and engaged in the most energetic activities were at most risk. Mild exercise like swimming did not increase the chances of a miscarriage.

The study authors wrote, “The study suggests that leisure-time exercise during pregnancy, and particularly high-impact exercise, is associated with an increased risk of miscarriage in the early stage.”

Exercise in later stages does not have an effect on the risk.

Anne-Marie Nybo Andersen, of the University of Southern Denmark in Odense, and her co-workers asked the women what type of exercise programs they followed at different times during pregnancy, and gathered data on those who had suffered a miscarriage.

The group discovered that the risk of miscarriage augmented with the quantity of exercise. Those who did over seven hours a week in weeks 11 to 14 of their pregnancy increased their risk about four times.

The type of exercise also made a difference as well. Those who jogged and played ball games in this phase advanced their risk of miscarriage over four times. Even low-impact work outs including dancing or walking doubled up the risk.

These increases were from a low base. Generally only about 3.5% of the pregnancies resulted in a miscarriage.

John Newnham, head of the school of women’s and Childs health at the University of Western Australia in Perth, stated New Scientist magazine that the results should not depress pregnant women from taking moderate exercise.