None of these patients were on any medication at the time of collection of blood samples. All subjects signed an informed written consent form. Demographic and clinical data were collected during routine obstetric visits. Healthy pregnant women did not suffer from medical conditions, such as diabetes or obesity and none of them had a history of small for gestational age (SGA) or hypertensive disorders in any previous pregnancy. Maternal and infant medical records were reviewed to collect detailed information concerning antepartum labor, delivery characteristics and condition of the newborn, including birth weight and gestational age at delivery.