OP13 .04: The effect of antenatal dietary and lifestyle advice on fetal growth in women who are overweight or obese: findings from the LIMIT randomised trial

Abstract

OBJECTIVES: Overweight and obesity are recognized risk factors for fetal growth disturbances, with associated maternal and fetal risks. We aimed to assess the effect of an antenatal dietary and lifestyle intervention on fetal growth at 28 and 36 weeks gestation. METHODS: We conducted a randomised controlled trial evaluating the effect of a dietary and lifestyle intervention for women who were overweight or obese during pregnancy on maternal and infant health outcomes. Women were eligible for the LIMIT trial with a BMI >/= 25kg/m2, and a live singleton pregnancy. Fetal biometric growth measures (biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL) and estimated fetal weight (EFW)) were assessed prospectively at 28 and 36 weeks' gestation, and Z-scores calculated for each fetus using the ASUM Ultrasonic Fetal Measurement Standards and the Hadlock C chart. Ultrasound measurements were analysed using linear mixed effects models, with adjustment for potential confounding factors. Growth velocities were analysed using linear regression models to assess the effect of intervention, with appropriate adjustments. Statistical significance was assessed at the 2-sided p < 0.05 level. All analyses were performed using SAS v9.3 (Cary, NC, USA). RESULTS: Of women who consented to the LIMIT trial, 78 % attended for a research ultrasound at 28 (1733 scans) and 36 weeks (1713 scans) gestation. Maternal overweight and obesity was associated with increased biometric measures of fetal growth at 28 and 36 weeks when compared with published normal values. An antenatal dietary and lifestyle intervention did not result in any significant difference in biometric measures of fetal growth at 28 or 36 weeks gestation. CONCLUSIONS: An antenatal dietary and lifestyle intervention does not result in any significant difference in static measures of growth or growth velocities in the third trimester.