Optimising gestational weight gain and improving maternal and infant health outcomes through antenatal dietary, lifestyle and exercise advice: the OPTIMISE randomised trial.

Women randomised to the Lifestyle Advice Group will receive comprehensive dietary advice to optimise gestational weight gain, utilising a combination of dietary, exercise and behavioural strategies. Women will be interviewed by a research dietitian and research assistants, and receive a multi-faceted series of inputs consisting of a combination of both individual and group face-to-face sessions, as outlined below. Over the course of pregnancy, each woman will receive 2 (1x1hr before 20 weeks, and 1x0.5hr at 28 weeks) sessions with the dietitian either one on one or as a small group of two to three women, and 4 one on one telephone contacts (at 22, 28, 34 and 36 weeks) with the research assistant. The intervention has been designed to maximise flexibility and choice for women, while providing advice that is both simple and easy to incorporate into each individual’s lifestyle. The timing and location of these sessions will again be designed to maximise flexibility and choice. Dietary advice provided will be consistent with current Australian dietary standards, and designed to limit gestational weight gain. The dietary intervention will maintain a balance of carbohydrates, fat and protein, while specifically encouraging women to reduce their intake of energy dense and non-core foods high in refined carbohydrates and saturated fats, while increasing their intake of fibre, and promoting consumption of two serves of fruit and five serves of vegetables each day. Recommendations and dietary targets will be individualised, taking into account each woman’s basal metabolic rate and activity levels. Tailoring of the intervention will be informed by stage theories of health decision making that propose that individuals progress through a series of cognitive phases when undertaking behavioural change. Initially, there will be a planning session with a research dietitian, in which women will be provided with written dietary and activity information, an individual diet and physical activity plan, a food and activity diary, recipe book and example menu plans. Women will be encouraged to set achievable goals for dietary and exercise change, supported to make these lifestyle changes and to self-monitor their progress. Women will be encouraged to involve their partner or significant support person in the individual and group intervention sessions. These principles will be reinforced at subsequent dietitian visits and during the telephone sessions in a similar format to a community intervention for women in the postpartum period. Women will be asked to complete a food frequency questionnaire, exercise diary, and quality of life assessments at trial entry, 28 and 36 weeks gestation, and six and 12 months postpartum. Their weight will be recorded at trial entry, and at each contact, including at 36 weeks gestation or nearest to birth, and 6 and 12 months post-partum. All women will be encouraged to attend for a research ultrasound at 28 and 36 weeks gestation that does not constitute routine clinical care, to monitor fetal growth and well-being, and in particular the development of small for gestational age infants. Care during pregnancy and birth will be according to the practices of the hospital at which the woman is booked to give birth. After birth, information will be obtained relating to birth and infant outcomes from the case notes by the research assistant and the delivery form completed. Similarly, the postnatal and neonatal forms will be completed for each live born infant after discharge from hospital. Data collection forms will be checked and signed by the local research coordinator. At six months and 1 year postpartum, women will be contacted to complete a questionnaire about their emotional wellbeing, infant feeding practices, infant development, and attend an assessment with a research assistant who will measure maternal and infant height/length, weight, anthropometry, and blood pressure.