The included trials studied the effect of interventions on women with any BMI,7 25-30 32 37-40 42-50 52 54-66 mostly obese and overweight women,31 33 53 or only obese women24 29 34-36 51 59 67 (clinical characteristics of all identified studies are in appendix 3 on bmj.com). Five randomised trials included pregnant women with a diagnosis of gestational diabetes mellitus28 31 34 57 58 and one included women with pre-existing diabetes.32 Typical dietary interventions included a balanced diet consisting of carbohydrates, proteins, and fat and maintenance of a food diary.Typical interventions based on physical activity included light intensity resistance training, weight bearing exercises, and walking for 30 minutes. The interventions in the mixed approach included counselling sessions, education concerning the potential benefit of diet and physical activity, and feedback on weight gain in pregnancy. The mixed approach used techniques of behavioural modification to give the women insight into controlling periods of emotional eating and preventing binge eating sessions. The quality of the studies varied (fig 2⇓). One study was available only as an abstract, and data were not included in the meta-analysis.24