Introduction. Women who commence pregnancy with a normal body mass index (BMI) are at the greatest risk of excessive gestational weight gain, impacting on infant birthweight, pregnancy-related complications and postpartum weight retention. Our aim was to review systematically the effect of antenatal dietary and lifestyle interventions in pregnant women with a normal BMI on maternal and infant outcomes. Material and methods. We searched the Cochrane Controlled Trials Register, PubMed, Medline, and the Australian and International Clinical Trials Registry with the date of the last search in July 2015. We included all published, unpublished and ongoing randomized trials recruiting women of a normal BMI, comparing dietary and/or lifestyle interventions with standard antenatal care. Results. Twelve randomized controlled trials were identified, involving a total of 2713 pregnant women, with five studies reporting clinical data for 714 women with a normal BMI. Women who received a dietary and lifestyle intervention were less likely to experience gestational weight gain [four studies, 446 women; mean difference -1.25 kg; 95% confidence interval (CI) -2.39 to -0.11], weight gain above the Institute of Medicine guidelines (four studies, 446 women; risk ratio 0.66; 95% CI 0.53-0.83) and hypertension (two studies; 243 women; risk ratio 0.34; 95% CI 0.13-0.91). There were no statistically significant differences in the occurrence of gestational diabetes, cesarean section or birthweight greater than 4 kg. Conclusions. While providing an antenatal dietary and lifestyle intervention for pregnant women of normal BMI appears to reduce gestational weight gain, the review was limited by the relatively small available sample size. Further well-designed randomized controlled trials are required.