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The group collectively gathered data from over 12,500 pregnant women randomised in 36 trials which compared the effects of dieting (including restriction of sugar-sweetened beverages, promoting low-fat dairy products, increase in fruits and vegetables) and physical activity (moderate intensity including aerobic classes and stationary cycling, and resistance training for muscle groups).


The interventions significantly reduced the mother’s weight gain during pregnancy by an average of 0.7 kg compared to the control group and lowered the odds of the mother having a caesarean section by about 10 percent. There was no strong evidence that the interventions affected offspring outcomes such as stillbirth, underweight or overweight births, or admission to a neonatal intensive care unit. The lack of adverse effects should reassure mothers who have traditionally been advised not to undertake structured exercise or manage their diet in pregnancy.


The study was funded by The National Institute for Health Research (NIHR) Health Technology Assessment (HTA) programme and its results were recently used by the UK Chief Medical Officers in the Department of Health’s infographics on physical activity in pregnancy, which recommended at least 150 minutes of moderate intensity activity every week.

 The i-WIP Collaborative Group was established in 2013 and gathered researchers who conducted trials on the effect of diet and physical activity based interventions in pregnancy. The main aim of establishing the i-WIP Collaborative Group was to conduct an Individual Participant Data (IPD) meta-analysis of randomised controlled trials on the effect of diet and physical activity in pregnancy which has been published in the British Medical Journal in 2017. 

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