Objectives To evaluate the effects of a counselling intervention on excessive weight gain during pregnancy and postpartum weight retention.Design The New Life(style) study was a randomised trial with a control group (n = 113) and an intervention group (n = 106).Setting Midwife practices in the Netherlands.Population Women with a healthy pregnancy, expecting their first baby.Methods The intervention consisted of four face-to-face counselling sessions about weight, physical activity and diet during pregnancy, and one session by telephone after delivery.Main outcome measures Weight was objectively assessed at 15, 25 and 35 weeks of gestation, and again at 8, 26 and 52 weeks postpartum. In regression models, the intervention effect on gestational weight gain and postpartum weight retention was assessed.Results Women gained on average 11.3 kg (SD 3.7 kg) from early to late pregnancy. Women were 1.0 kg (SD 5.3 kg) lighter at 52 weeks postpartum compared with early pregnancy. The intervention had no effect on gestational weight gain (B = )0.05; 95% CI )1.10 to 1.00) or postpartum weight (B = 0.94; 95% CI )2.41 to 0.53) in the total study group. In a subgroup of overweight and obese women (n = 47), a favourable trend on all outcomes was observed, but none of the differences were statistically significant. ConclusionThe lifestyle counselling intervention evaluated in this study did not have an effect on excessive weight gain or postpartum weight retention. Our findings for overweight and obese women need to be confirmed in a larger, well-designed randomised trial.Keywords Gestational weight gain, lifestyle counselling, weight retention.Please cite this paper as: Althuizen E, van der Wijden CL, van Mechelen W, Seidell JC, van Poppel MNM. The effect of a counselling intervention on weight changes during and after pregnancy: a randomised trial. BJOG 2013;120:92-99.