The value of fetal placental ratio and placental efficiency in term human pregnancy and complications

BackgroundFetal birth weight and placental weight have been extensively studied and used for clinical assessment of fetal development and maternal health. The ratio of fetal and placental weight as a tool for clinical use in human pregnancy is less studied. We compared the fetal birth weight, placental weight and fetal placental ratio in term pregnancy to see if fetal and placental ratio is useful in assessment of maternal health and pregnancy complication as well as fetal growth and development in singleton pregnancy. Material and methodsWe have collected the fetal birth data, maternal pregnancy data and placental pathology data from March 2000 to November 2021 in a single urban hospital. We compared the fetal birth weight, placental weight and fetal placental ratio in assessment of fetal growth, maternal pregnancy complications, and placental pathology with special emphasis on the role of fetal placental ratio. ResultsA total 3302 pairs of neonates and placentas from term singleton pregnancy were reviewed and fetal birth weight and placental weight were moderately correlated with Pearmans correlation coefficiency R=0.66. Fetal placental ratio as a proxy of placental efficiency was significantly associated with various pregnancy complications and placental pathology, and these associations were different from those of fetal birth weight or placental weight alone. High placental efficiency (90 percentile or greater) was associated with ethnic White, SARS-CoV2 status, category 2 fetal heart tracing and maternal inflammatory response in placenta while low placental efficiency (less than 10 percentile) was associated with ethnic Black, Asian and Hispanic, preeclampsia/pregnancy induced hypertension and gestational diabetes mellitus. ConclusionFetal placental ratio was shown to be a useful indicator different from fetal birth weight and placental weight alone. Maternal and environmental factors were shown to have differential effects on fetal and placental growth. Understanding the mechanism of differential fetal and placental growth will help better manage the clinical relevant conditions such as IUGR and macrosomia.