Women who take part in exercise or diet programs, or a combination of the two, during pregnancy can prevent excessive weight gain, according to a review of past research.
The review incorporates dozens of new studies to update a previous review that did not find enough evidence to support the use of diet and exercise during pregnancy.
After including the new studies, the new review found "high-quality evidence" to show diet, exercise or both can reduce the risk of excessive weight gain during pregnancy.
Other benefits may include a lower risk of cesarean delivery, excessive birth weight, and respiratory problems in the newborn, particularly for high-risk women receiving combined diet and exercise interventions.
The U.S. Institute of Medicine says the amount of weight women should gain during pregnancy varies depending on their pre-pregnancy weight.
For example, a normal-weight woman should gain between 25 and 35 pounds, while an overweight woman should gain between 15 and 25 pounds. Obese women should gain even less.
Gaining too much weight is tied to an increased risk of complications for both mother and child.
For the new review, the researchers examined data from 49 randomized controlled trials – the "gold standard" of medical research – involving a total of 11,444 pregnant women.
The women were randomly assigned to a diet, exercise, a combination of the two or standard care. The diets and exercise programs varied, but could include low-glycemic diets and unsupervised exercise.
Women who took part in diet, exercise or combination programs were about 20 percent less likely than women in standard-care groups to gain too much weight while pregnant.
The women who took part in diet, exercise and combination programs were also less likely to develop high blood pressure during pregnancy, compared to those in the standard care group.
There was no clear benefit among the women in the diet and exercise groups when the researchers looked at other complications, such as cesarean delivery.
The researchers said women who gain too much weight might not be able to lose it after the baby is born. Then, during the next pregnancy the woman is already heavier and that may increase the risk of complications.
They cautioned, however, that women should check with their doctors before starting a diet and exercise program during pregnancy.
Source: The Cochrane Library, online June 11, 2015.
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