Volumetric Assessment of Longitudinal Placental Growth

Abstract

INTRODUCTION: Small placental volumes are associated with adverse pregnancy outcomes such as intrauterine growth restriction. Normative growth curves for the fetus exist but not for normal placental growth. This study examines longitudinal placental growth pattern in a healthy cohort. METHODS: This prospective longitudinal cohort study of placental volume enrolled 12 gravidas with uncomplicated pregnancies less than 12 weeks of gestation. Placental volumes were measured for each at 12, 17, 22, 27, and 32 weeks of gestation. Placental volume was calculated with VOCAL (Virtual Organ Computer-aided AnaLysis) in the 4DVIEW 6.0 software. Placental growth rate was calculated using the logistic growth function Linear regression was used for correlation between actual and predicted placental volume. P<.05 was significant. RESULTS: Eleven participants were analyzed and one with preeclampsia was excluded. Placental growth rate was calculated and growth constant, rp (0.3±0.037), empirically determined. The fitted plot showed exponential growth to 27 weeks of gestation with growth slowing thereafter with sigmoidal shape (Fig. 1). The actual and predicted placental volumes were strongly correlated (R2=0.99, P<.001; Fig. 2).CONCLUSION: This study suggests placental growth may be exponential until 27 weeks of gestation in uncomplicated pregnancies. Maternal and fetal variables may influence placental volumetric growth later in pregnancy. Knowledge of the normal placental growth pattern is an initial step in understanding the association of placental volumetric growth and perinatal outcomes.