Stress hormones and acid-base status in human fetuses at term delivery: the effect of delivery method.

To evaluate the effect of delivery mode on fetal stress hormones and acid-base status and also to investigate the relationship between fetal acidemia and these hormones. 64 women with term pregnancies were studied. All had singleton, healthy pregnancies. Twenty one women were delivered by spontaneous vaginal route, 23 by vaginal route following oxytocin infusion and 20 by elective caesarean section. Umbilical cord blood samples were obtained immediately following the delivery. Blood gas (pH, pCO2, pO2) and hormonal analysis (Cortisol, dehydroepiandrosterone sulphate, prolactin, androstenedione) were done in arterial and venous cord blood samples respectively. Higher pO2 and prolactin, lower pH levels were found in caesarean section compared to other two groups (p < 0.05). At the time of delivery 11 infants had acidemia (pH < 7.20) as judged by pH of umbilical arterial blood. Acidemic group had higher cortisol and pCO2; lower pH and pO2 levels compared to non-acidemic group (p < 0.05). Method of delivery may affect acid-base and hormonal status of human fetus. Fetal acidemia may alter fetal adrenal steroidogenesis leading to increased fetal cortisol production.