New research suggests that women who exercise during pregnancy are less likely to have gestational diabetes, and the exercise also helps to reduce maternal weight gain.

Gestational diabetes is one of the most frequent complications of pregnancy. It is associated with an increased risk of serious disorders such as pre-eclampsia, hypertension, preterm birth, and with induced or caesarean birth. It can have long term effects on the mother including long term impaired glucose tolerance and type 2 diabetes. The children of mothers with gestational diabetes are more likely to become overweight or obese and have a higher risk of developing diabetes themselves.

Researchers found that exercise reduced the risk of gestational diabetes by more than 30 percent -- for women who exercised throughout pregnancy this was even greater (36 percent). This effect was strongest for women who combined toning, strength, flexibility and aerobic exercise.

"Exercise is not something to be feared during pregnancy -- the moderate levels of exercise used in these studies had significantly positive effects on health and were found to be safe for both mother and baby," Gema Sanabria- Martinez, lead author of the study, said in a statement.

For the study, researchers from Span analyzed 13 trials involving more than 2,800 women.

They found that exercise was also helpful in reducing excessive weight gain -- those who exercised were on average a kilogram lighter. This held true for the weight gain even if the exercise program was started in the second trimester of pregnancy.

The findings are detailed in BJOG: an International Journal of Obstetrics and Gynaecology.