"Women who take part in exercise diet programs or a combination of the two during pregnancy can prevent excessive weight gain according to a fresh 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 highquality evidence to show diet exercise or both can reduce the risk of excessive weight gain during pregnancy write the researchers in The Cochrane Library.  Other benefits may include a lower risk of cesarean delivery excessive birth weight and respiratory  problems in the newborn particularly for highrisk women receiving combined diet and exercise interventions add the researchers led by Benja Muktabhant of Khon Kaen University in Thailand.  The U.S. Institute of Medicine says the amount of weight women should gain during pregnancy varies depending on their nonpregnancy weight.  For example a normalweight woman should gain between  and  pounds while an overweight woman should gain between  and  pounds. Obese women should gain even less.  Gaining too much weight is tied to an increased risk of complications for both mother and child according to the researchers who completed the review for The Cochrane Collaboration an international organization that evaluates medical research.  For the new review the researchers examined data from  randomized controlled trials which are considered the gold standard of medical research. They were able to combine data from  trials involving a total of  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 lowglycemic diets and unsupervised exercise.  Women who took part in diet exercise or combination programs were about  percent less likely than women in standardcare groups to gain too much weight while pregnant the researchers report.  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 but it did look like there may be some benefit they write.  While the new study generally did not show fewer complications in the diet and exercise group Dr. Loralei Thornburg told Reuters Health that its good that there was no increase in complications.  This was very reassuring that there wasnt an increased risk of preterm birth with moderate exercise said Thornburg a highrisk pregnancy expert at the University of Rochester Medical Center in New York.  Most people gain more weight than they probably should during pregnancy Thornburg who was not involved with the review told Reuters Health.  She said women who gain too much weight may 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.  In the next pregnancy if you dont get it off you may go from obese to very obese Thornburg said.  ADVERTISING She cautioned however that women should check with their doctors before starting a diet and exercise program during pregnancy.  SOURCE bit.lyClYDc httpbit.lyClYDc The Cochrane Library online June  . Our StandardsThe Thomson Reuters Trust Principles. httpthomsonreuters.comenaboutustrustprinciples.html"