Blood collection
CLOT
Maternal blood samples (5 ml) were extracted from the antecubital vein in standardized fasting conditions (at the 16th and 34th g.w.), and arterial and vein cord blood samples were extracted immediately after delivery. All blood samples were collected in serum tubes and were allowed to clot (coagulation) at room temperature for 30 min. Subsequently, samples were centrifuged at 1750 rpm for 10 min at 4°C in a refrigerated centrifuge (GS−6R Beckman Coulter) to obtain serum, which was aliquoted and frozen at −80°C until analyzed.