Interventions for preventing excessive weight gain during pregnancy

A large proportion of women gain more weight than is recommended during pregnancy. Excessive weight gain increases the risk of complications for both the mother and her infant. These include miscarriage, development of diabetes mellitus or pregnancy-induced hypertension, a high birthweight infant and the likelihood of caesarean section. We reviewed 28 randomised controlled studies that involving more than 3000 women, mostly from developed countries, to assess the effectiveness of interventions for preventing excessive weight gain during pregnancy (27 of the studies with 3964 women contributed data to the analyses). Results on preventing excessive weight gain during pregnancy were limited to studies that included this as an outcome. There were five interventions in the general population and two interventions in high-risk groups which seemed to reduce average weight gain during pregnancy. Few studies looked at excessive weight gain during pregnancy and only one of the interventions they used resulted in significantly reduced rates of excessive weight gain. It is not appropriate for us to recommend any one intervention for preventing excessive weight gain during pregnancy because most of the studies identified were of poor quality and the effects of the interventions were generally small. There is an urgent need for more well-designed studies with adequate sample sizes to be able to recommend effective interventions.

Authors' conclusions: 

There is not enough evidence to recommend any intervention for preventing excessive weight gain during pregnancy, due to the significant methodological limitations of included studies and the small observed effect sizes. More high-quality randomised controlled trials with adequate sample sizes are required to evaluate the effectiveness of potential interventions.

Read the full abstract...
Background: 

Excessive weight gain during pregnancy is associated with multiple maternal and neonatal complications. However, interventions to prevent excessive weight gain during pregnancy have not been adequately evaluated.

Objectives: 

To evaluate the effectiveness of interventions for preventing excessive weight gain during pregnancy and associated pregnancy complications.

Search strategy: 

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (20 October 2011) and MEDLINE (1966 to 20 October 2011).

Selection criteria: 

All randomised controlled trials and quasi-randomised trials of interventions for preventing excessive weight gain during pregnancy.

Data collection and analysis: 

We assessed for inclusion all potential studies we identified as a result of the search strategy. At least two review authors independently assessed trial quality and extracted data. We resolved discrepancies through discussion. We have presented results using risk ratio (RR) for categorical data and mean difference for continuous data. We analysed data using a fixed-effect model.

Main results: 

We included 28 studies involving 3976 women; 27 of these studies with 3964 women contributed data to the analyses. Interventions focused on a broad range of interventions. However, for most outcomes we could not combine data in a meta-analysis, and where we did pool data, no more than two or three studies could be combined for a particular intervention and outcome. Overall, results from this review were mainly not statistically significant, and where there did appear to be differences between intervention and control groups, results were not consistent. For women in general clinic populations one (behavioural counselling versus standard care) of three interventions examined was associated with a reduction in the rate of excessive weight gain (RR 0.72, 95% confidence interval 0.54 to 0.95); for women in high-risk groups no intervention appeared to reduce excess weight gain. There were inconsistent results for mean weight gain (reported in all but one of the included studies). We found a statistically significant effect on mean weight gain for five interventions in the general population and for two interventions in high-risk groups.

Most studies did not show statistically significant effects on maternal complications, and none reported significant effects on adverse neonatal outcomes.