Patients and specimens
Biopsies of peripheral and central portions were collected from 496 placentas between March 2011 and March 2014, immediately after each woman delivered the newborn, and subsequently separated on fetal and maternal interfaces. The collection of placental tissue was performed using different sterile surgical materials for each face of the placenta and the collected fragments were placed into microtubes containing 300μL of TE buffer (10 mmol/L Tris-HCL pH 8,0; 1mmol/L EDTA).
The collection of umbilical cord blood for molecular assays was performed after cord clamping. Blood from the umbilical cord was collected using a syringe (27/5 needle) by puncturing 3ml of blood.