Placental Biometric Parameters: The Usefulness of Placental Weight Ratio and Birth/Placental Weight Ratio Percentile Curves for Singleton Gestations as a Function of Gestational age

Objective: To produce reference values for the placental weight (PW), Placental diameters (PDs), Placental thickness (PT), placental weight ratio (PW-R) and birth/placental weight ratio (BPW-R) in singleton gestations as a function of gestational age (GA). Study Design and Setting: A retrospective 4-years case study of singleton placentas reports between, 1st of January 2014 to 31st of December 2017. The placentas were sent for histopathological diagnosis to Embryofetal Pathology Laboratory, Centro de Genetica Clínica (CGC), Porto, Portugal. In a cohort of singleton placentas, PW, PDs, PT, PW-R, and BPW-R were analyzed to produce percentile curves. Considering the inclusion criteria, 1,951 singleton placentas were selected from a sample of 7,321 placentas. We recorded the PW, PDs, PT, PW-R, and BPW-R between 12th and 41st GA. Results: PW, PDs, PW-R and BPW-R tables and percentiles curves for singleton placentas across GA were produced. Conclusions: Placental percentile curves may act as a reference for other populations as well until population-specific curves can be produced. PDs could predict placental volume and could help to estimate the prenatal PW-R and BPW-R.