Diminished Late Gestation Placental Volume in Fetal Heart Disease and Implications for Birth Anthropometrics

Background: The primary objective of this study was to compare the in vivo placenta volume across gestation in fetuses with congenital heart disease (CHD) and healthy controls. The second objective was to determine the relationship between placental volume and both CHD characteristics and neonatal birth anthropometrics. Methods: Pregnant women with a fetal diagnosis of CHD and healthy pregnancies were enrolled in a longitudinal observational study at Children’s National Hospital. A total of 451 fetal MRIs were analyzed from 284 pregnant women (112 mothers/182 scans with CHD; 172 controls/261 scans). In vivo placentas were manually segmented to derive volumes and z-scores. Z-scores were computed from placental volume data derived from control participants for weekly GA bins using means and standard deviations. Z-scores were then assigned to the CHD cohort. A linear mixed effects model with random intercepts clustered by subject was applied to examine the associations between placental volumes and CHD characteristics, including comparing placental volumes between groups according to gestational windows. Results: Overall, placental volumes in CHD were not significantly different than placental volumes from controls. However, in infants delivered at term age, CHD placental volume plateaued in the final four weeks of gestation. Smaller in vivo CHD placental volume z-scores were associated with decreased weight at delivery (p ≤ 0.0001). Conclusions: This study identifies that in vivo CHD placentas are abnormal in the final four weeks of gestation. Smaller CHD placentas were associated with decreased birth weight, underscoring the importance of placental development in neonatal anthropometrics.