Placental weight percentiles and its relationship with fetal weight according to gestational age in an urban area of Buenos Aires

Background: The placental weight (PW) and the rates of their relationship with birth weight (BW) (BW / PW, PW / BW) predict perinatal morbidity and mortality and future health outcomes.

Objective: Estimate percentiles of PW and indices by sex and gestational age (GA) corresponding to 867 live born from Sardá Maternity of Buenos Aires and compare with international references.

Methods: Stillbirth, multiple pregnancy, gestational age <22 and > 42 weeks and PW <100g and > 2500g were excluded. Maternal and fetal characteristics were: age, education, smoking, parity, diabetes, preeclampsia, chorioamnionitis, growth restriction, prematurity and congenital anomalies. Summary statistics and percentiles with the LMS method were calculated. The comparisons were performed using Student t-test, ANOVA and international references.

Results: Average maternal age 24 years , education 10.1 years, 24.5% primiparous, 12.6% smokers, 4.9% had diabetes, 8.7% preeclampsia, 7.9% chorioamnionitis and 13.0% fetal growth restriction; 55.3% of newborns were male, 51.6% preterm, 18.9% small for gestational age and 7.1% malformed. On average BW and GA were 2581g and 35.6 weeks, respectively. High positive correlation between GA with PW and BW/PW, and negative with PW/BW was observed (p <0.001); placental weight and indices were higher in males. Percentiles of PW, BW / PW and PW / BW are depicted. Differences with references ranged from 0.46% -13%, 4.91% -12.1% and 5.81% -14% for PW, BW / PW and PW / BW, respectively.

Conclusions: Percentiles generated are applicable in research on the relationship of the placenta with perinatal outcomes and health throughout the life cycle.