Placental histopathology in the extremely low birth weight infants

Our objective was to evaluate the placental histopathology (PH) in extremely low birth weight infants (ELBW, birth weight < 1000 g) and to determine if placental histopathological findings are associated with neonatal mortality in them. The PH of all ELBW infants (gestational age 23-30 weeks) born during a 3-year study period was prospectively evaluated and compared with term infants (gestational age >= 37 weeks). Additionally PH of ELBW infants who expired within 28 days of life was compared with those who survived beyond 28 days. Student's t test, chi(2) test and Pearson's correlation coefficient tests were utilized for data analysis. The occurrences of placental infection (chorioamnionitis, HCA), umbilical cord inflammation (funisitis, vasculitis, and subacute necrotizing funisitis, analyzed collectively as HFV), and abruption were higher in ELBW (n = 105) compared to term infants (n = 61, p = 0.001, 0.0002, and 0.0002, respectively). Placental findings did not differ between the surviving (n = 71) and nonsurviving (n = 51) ELBW infants. Birth weight and gestational age were higher in the surviving group (p = 0.003 and 0.001, respectively). Placental abruption was found more commonly in the presence of HCA and HFV in ELBW infants as opposed to maternal hypertension in term infants. All ELBW placentas with HFV had concomitant findings of HCA whereas only 42% of ELBW placentas with HCA had findings of HFV compared to 24% in term infants (p = 0.09). There was a weak inverse correlation between HCA and birth weight in all (r = -0.3, p = 0.01) but not in ELBW infants (r = 0.2, p = 0.07). We conclude that placental and umbilical cord inflammation and placental abruption are more commonly present in ELBW compared to term infants. However, these findings do not contribute to neonatal mortality in ELBW infants. Forty-two percent of placental (maternal) inflammation cases have concomitant cord (fetal) inflammation in ELBW infants. Finally HCA correlates inversely with birth weight in neonates.