Women in the control arm received routine antenatal care. As is standard practice at our institution, this did not involve any formal dietary advice or specific advice about gestational weight gain. Women randomised to the intervention group attended one dietary education session lasting two hours in groups of two to six women with the research dietitian. The mean gestational age of those attending the dietary session was 15.7 (SD 3.0) weeks. The diet was designed to meet current recommendations for pregnant women.22 Women were first advised on general healthy eating guidelines for pregnancy, following the food pyramid. The remainder of the education session focused on the glycaemic index—its definition, concept, and rationale for use in pregnancy. Women were encouraged to choose as many low glycaemic index foods as possible and to exchange high glycaemic index carbohydrates for low glycaemic index alternatives. Women received written resources about low glycaemic index foods after the education session (web appendix). The recommended low glycaemic index diet was eucaloric, and women were not advised to reduce their total caloric intake. The research dietitian met with the patients at 28 and 34 weeks’ gestation for reinforcement of the low glycaemic index diet and to answer any dietary queries they had.