Trials of interventions for pregnant women who are obese to lose weight and improve pregnancy outcomes.

Pregnant women who are obese risk serious complications for themselves and their children. The mother is more likely to develop diabetes or high blood pressure or pre-eclampsia during pregnancy, and the pregnancy may end in a miscarriage or stillbirth. The baby could have serious anomalies at birth, including spina bifida, cardiovascular anomalies, cleft lip and palate, or limb reduction anomalies. Some obese women have premature births. At birth, the labour may be longer and other complications can lead to a caesarean birth. The baby may also be bigger at birth than is normal, and there is evidence that the children of obese mothers go on to be obese. The advice for obese women in managing their weight during pregnancy is that weight loss should be avoided, and weight gain should be between 5.0 and 9.1 kg. Yet observational studies of large numbers of pregnant women indicate that some obese women, especially those who are heavier, lose weight during pregnancy. We do not have any clear results that indicate that losing weight when pregnant is safe for a mother who is obese, or for her baby. This Cochrane review aimed to evaluate trials that were designed for obese pregnant women to lose weight. No randomised controlled trials were found. We recommend that further research is conducted to evaluate the safety of interventions for weight loss when a woman is pregnant and obese for the mother and her baby.

Authors' conclusions: 

There are no trials designed to reduce weight in obese pregnant women. Until the safety of weight loss in obese pregnant women can be established, there can be no practice recommendations for these women to intentionally lose weight during the pregnancy period. Further study is required to explore the potential benefits, or harm, of weight loss in pregnancy when obese before weight loss interventions in pregnancy can be designed. Qualitative research is also required to explore dietary habits of obese pregnant women, especially those who are morbidly obese.

Read the full abstract...

Being obese and pregnant is associated with substantial risks for the mother and her child. Current weight management guidance for obese pregnant women is limited. The latest recommendations suggest that obese pregnant women should gain between 5.0 and 9.1 kg during the pregnancy period, and weight loss is discouraged. However, observational studies indicate that some obese pregnant women, especially those who are heavier, lose weight during pregnancy. Furthermore, some obese pregnant women may intentionally lose weight. The safety of weight loss when pregnant and obese is not substantiated; some observational studies suggest that risks associated with weight loss such as pre-eclampsia are improved, but others indicate that the incidence of small- for-gestational infants are increased. It is important to evaluate interventions that are designed to reduce weight in obese pregnant women so that the safety of weight loss during this period can be established.


To evaluate the effectiveness of interventions that reduce weight in obese pregnant women.

Search strategy: 

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 July 2012) and contacted experts in the field.

Selection criteria: 

Randomised controlled trials, 'quasi-random' studies and cluster-randomised trials comparing a weight-loss intervention with routine care or more than one weight loss intervention. Cross-over trials were not eligible for inclusion.

Data collection and analysis: 

We identified no studies that met the inclusion criteria for this review.

Main results: 

There were no included trials.