Background There remains a paucity of data into the effect of low glycaemic index (GI) healthy eating pregnancy interventions postpartum. Aim: To examine the impact of a low glycaemic index diet during pregnancy on maternal diet and weight at 3 months postpartum, analysis from the ROLO (Randomised cOntrol trial of LOw glycaemic index (GI) diet versus no dietary intervention to prevent recurrence of fetal macrosomia) study.

Methodology This was a postpartum analysis of 460 participants of the ROLO study 3 month postnatally. Questionnaires on weight, physical activity, breastfeeding, supplement use, food label reading and dietary change since the intervention were completed.

Results The intervention group had significantly higher weight loss from pre-pregnancy to 3 months postpartum than the control group (1.314 vs 0.119 kg, p = 0.022). The intervention group reported higher levels of adherence to a low GI diet (p < 0.001) and food label reading (p = 0.032) and had a lower glycaemic load (GL) (128.22 vs 145.18, p = 0.014) but not GI intake (54.51 vs 54.66, p = 0.809) than the controls.

Conclusions Low GI dietary intervention in pregnancy results in improved health-behaviours and continued reported compliance at 3 months postpartum possibly mediated through portion control. Reduced gestational weight gain in pregnancy persisted at 3 months postpartum which has important positive implications for overweight and obesity in later life.