The contribution of maternal obesity to fetal body composition

Abstract

Background: There are well established links between maternal obesity, high infant birth weight and childhood obesity. However, the contribution of specific maternal dietary components and specific cardiometabolic and inflammatory measures to fetal growth and adiposity among overweight and obese women warrant further investigation. There is limited information describing the impact of maternal BMI on fetal growth trajectories and correlation between fetal and neonatal measures of growth and adiposity. Methods: This thesis contains a series of secondary analyses involving 911 overweight and obese women who participated in the LIMIT trial and who were randomised to the ‘Standard Care’ group. Fetal biometry and adiposity measurements were obtained from ultrasound assessments at 28 and 36 weeks gestation. Analyses investigated: 1) The contribution of maternal BMI to fetal growth trajectories; 2) The contribution of maternal dietary factors to fetal growth and adiposity; 3) The contribution of maternal cardiometabolic and inflammatory markers to fetal growth and adiposity; and 4) The correlation between fetal and neonatal anthropometric measures. Results: The key findings of this thesis are 1) Increased maternal BMI is associated with incremental increases in growth velocity of the fetal abdomen and estimated fetal weight. 2) Pregnant women with BMI ≥ 40.0kg/m2 showed the greatest increase in all fetal biometry z-scores, abdominal fat mass and abdominal area at 28 and 36 weeks gestation. 3) Maternal dietary measures are not consistently associated with fetal growth or adiposity. 4) Increased maternal concentrations of adiponectin are associated with a reduction in fetal abdominal circumference and estimated fetal weight. 5) Increased maternal triglyceride concentrations are associated with an increase in fetal abdominal circumference z-score and estimated fetal weight at 36 weeks. 6) Ultrasound assessment of fetal weight at 36 weeks gestation is a reliable indicator of infant birth weight, and ultrasound assessment of fetal HC and AC at 36 weeks are strongly correlated with newborn measures. Conclusions: Among women who are overweight or obese, the contributions of maternal BMI, dietary factors and cardiometabolic and inflammatory markers to fetal growth and adiposity are highly complex. This study has confirmed that high maternal BMI is associated with higher fetal growth. Therefore, evaluation of interventions to modify fetal growth and adiposity through improving maternal health prior to conception are required.