Limiting weight gain in overweight and obese women during pregnancy to improve health outcomes: the LIMIT randomised controlled trial

BACKGROUND: Obesity is a significant global health problem, with the proportion of women entering pregnancy with a body mass index greater than or equal to 25 kg/m(2 )approaching 50%. Obesity during pregnancy is associated with a well-recognised increased risk of adverse health outcomes both for the woman and her infant, however there is more limited information available regarding effective interventions to improve health outcomes. The aims of this randomised controlled trial are to assess whether the implementation of a package of dietary and lifestyle advice to overweight and obese women during pregnancy to limit gestational weight gain is effective in improving maternal, fetal and infant health outcomes. METHODS/DESIGN: Design: Multicentred randomised, controlled trial. Inclusion Criteria: Women with a singleton, live gestation between 10(+0)-20(+0 )weeks who are obese or overweight (defined as body mass index greater than or equal to 25 kg/m(2)), at the first antenatal visit. Trial Entry & Randomisation: Eligible, consenting women will be randomised between 10(+0 )and 20(+0 )weeks gestation using a central telephone randomisation service, and randomisation schedule prepared by non-clinical research staff with balanced variable blocks. Stratification will be according to maternal BMI at trial entry, parity, and centre where planned to give birth. Treatment Schedules: Women randomised to the Dietary and Lifestyle Advice Group will receive a series of inputs from research assistants and research dietician to limit gestational weight gain, and will include a combination of dietary, exercise and behavioural strategies. Women randomised to the Standard Care Group will continue to receive their pregnancy care according to local hospital guidelines, which does not currently include routine provision of dietary, lifestyle and behavioural advice. Outcome assessors will be blinded to the allocated treatment group. Primary Study Outcome: infant large for gestational age (defined as infant birth weight ≥ 90(th )centile for gestational age). Sample Size: 2,180 women to detect a 30% reduction in large for gestational age infants from 14.40% (p = 0.05, 80% power, two-tailed). DISCUSSION: This is a protocol for a randomised trial. The findings will contribute to the development of evidence based clinical practice guidelines. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry ACTRN12607000161426