Background We aimed to evaluate whether pre and perinatal education of pregnant women would reduce childhood overweight. Methods Four French centers included women at <= 21 gestational weeks (GWs) with body mass index (BMI) > 25 kg/m(2) before pregnancy. Patients were randomized to a control group (routine care including at least one dietary visit) or an intervention group (2 individuals (26 and 30 GW) and 4 group sessions (21, 28, 35 GW, 2 months postpartum)) aimed at educating the future mother regarding infant and maternal nutrition. The primary objective was to reduce post-natal excessive weight gain in the infant from birth to 2 years (NCT00804765). This project was funded by a grant from the National Programme for Hospital Research (PHRC-2007 French Ministry of Health). Results We included 275 women (BMI: 32.5 kg/m(2)). The rate of post-natal excessive weight gain was similar in the intervention (n = 132) and control (n = 136) groups by intention to treat (ITT: 59.1% vs 60.3% respectively, p = 0.84) in available data (AD, n = 206) and by per-protocol analysis (PP, n = 177). Two years after delivery, normalization of maternal BMI and number of infants with BMI < 19 kg/m(2) were not significantly different in the interventional group in ITT and in the control group. Although not significantly different in ITT, normalization of maternal BMI was more frequent in AD (n = 149: 12.9% vs 3.8%, p = 0.04) and 2-year-old infant BMIs were less likely to be > 19 kg/m(2) in the intervention group in AD (n = 204: 0% vs 6.8%, p = 0.014) and PP (n = 176: 0% vs 6.4%, p = 0.03). Conclusions An education and nutritional counseling program for overweight women, starting after 3 months of gestation, did not significantly change post-natal excessive weight gain of infants or prevent overweight in mothers and children 2 years after delivery.