Metformin and dietary advice to improve insulin sensitivity and promote gestational restriction of weight in pregnant women who are overweight or obese: the GroW Randomised trial.

Metformin and dietary and exercise advice. Women will commence at enrollment taking one 500 mg tablet once daily increasing to two tablets twice daily (2000 mg) over the first four weeks and continue until birth. 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, recipe book and example menu plans. Over the course of pregnancy, each woman will receive 1-2 sessions with the dietitian of up to 45 minutes duration, shortly after trial entry and again at 28 weeks gestation; and telephone calls of up to 20 minutes duration from the research assistant at 24, 32 and 36 weeks gestation. Dietary advice provided will be consistent with current Australian dietary standards, 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. Women will be encouraged to be active every day and will receive written information about exercise in pregnancy consistent with the Guidelines for exercise in pregnancy produce by the British royal College of Obstetricians and Gynaecologists.