Obese pregnant women have an increased risk of antenatal, intra- and post-partum complications. At present, there is limited evidence to support specific nutritional management of obese women in pregnancy, and guidelines are infrequently translated into practice.To implement an individually tailored nutrition program for obese pregnant women to reduce the rates of gestational diabetes mellitus (GDM), improve diet quality, achieve weight gain targets, limit gestational weight gain (GWG) and reduce complications for mother and child.A prospective dietary intervention study was conducted at a hospital in Melbourne, Australia, using a parallel control group from the Birthing Outcomes System (BOS) database. Obese pregnant women were included if they were ≤21 weeks gestation and aged ≥18 years. The intervention group received one face-to-face dietitian-delivered consultation, with reviews conducted over the phone.A total of 92 and 125 obese pregnant women were enrolled into the dietary intervention group and BOS control group, respectively. The diet quality of intervention participants improved, without significant differences in GWG across groups. In the control group, 19.3% of women developed GDM, compared to 6.5% in the diet group (P 0.013). However, after adjusting for ethnicity and body mass index, the association between the diet group and GDM incidence was no longer significant.This study demonstrates that a behavioural nutrition intervention, individually tailored for obese pregnant women can improve diet quality. A larger randomised controlled trial targeted at obese pregnant women, with comparable groups at baseline, is required to observe the effects of dietary improvement on GDM incidence, and other maternal and neonatal outcomes.