MATERNAL BODY COMPOSITION LATE IN PREGNANCY AND INFANT BODY COMPOSITION AT BIRTH

Background: Fat mass (FM) is significantly higher in neonates born to overweight and obese women, while no difference is found in fat free mass (FFM). Higher gestational weight gain (GWG) is also related to a greater neonatal birth weight and FM gain. However, no study has reported the relationship between maternal body composition during gestation and neonatal body composition at birth. Objectives: The primary aim of this study was to evaluate the relationship between maternal body composition late in pregnancy and neonatal body composition at birth. The secondary aim of this study was to investigate the association between maternal trimester-specific GWG and neonatal body composition at birth. Methods: Healthy pregnant women with a pre-pregnancy body mass index (BMI) between 18.5 to 39.99 kg/m2 were recruited. Maternal body composition (percentage body fat (% fat), FM, FFM, and total body water (TBW)) was measured using the four-compartment model during 34 to 39 weeks gestation and infant body composition (% fat, FM, and FFM) was measured using air-displacement plethysmography (ADP) within 72h after birth. Maternal GWG during the 1st (0 to 13 weeks), 2nd (14 to 28 weeks) and 3rd (29 weeks to delivery) trimesters were calculated using extracted body weight from medical records minus their self-reported pre-pregnancy weight. Multiple linear regression models were used to determine the relationship between maternal factors and neonatal body composition. Neonatal % fat, FM, and FFM were used as dependent variables. Maternal % fat, FM, FFM and TBW were used as independent variables for the primary aim and the 1st, 2nd, and 3rd trimester gestational weight gains were used as independent variables for the secondary aim. Maternal age, neonatal age at test, gender and gestational age were controlled in the models for the primary aim and maternal pre-pregnancy BMI, neonatal age at test, gender and gestational age were controlled in the models for the secondary aim. Results: Forty women completed visits for the primary aim and forty-five women completed visits for the secondary aim. Maternal body FFM and TBW were related to neonatal birth weight (r2 = 0.280, p = 0.011; r2 = 0.330, p = 0.007, respectively) and FFM (r2 = 0.521, p = 0.011; r2 = 0.519, p = 0.011, respectively). A trend of significance was found between maternal FM and neonatal birth weight (r2 = 0.224; p = 0.053) and FM (r2 = 0.052; p = 0.085). The relationship between trimester-specific GWG and neonatal body composition varied by maternal pre-pregnancy BMI category. Conclusions: Maternal body composition was related to neonatal birth weight, while maternal FFM and TBW were related to neonatal FFM but not FM at birth. The relationship between maternal GWG and neonatal body fat at birth was dependent on maternal pre-pregnancy BMI