Maternal and fetal serum levels of total cortisol and cortisone, unbound cortisol, and corticosteroid-binding globulin in vaginal delivery and cesarean section.

The levels of corticosteroid-binding globulin (CBG, transcortin), total cortisol, and unbound cortisol were measured in maternal and fetal serum at the time of cesarean section or vaginal delivery. While the total cortisol levels in maternal serum do not differ significantly in vaginal delivery as compared to cesarean section, cord serum cortisol levels are significantly higher after vaginal delivery. There are no differences associated with the route of delivery between the mean levels of CBG in cord and maternal blood. However, after the vaginal delivery the unbound cortisol level in maternal serum is more than twice as high as that at cesarean section and in cord serum it is seven times as high. These changes reflect changes in total cortisol and may represent a prelabor surge of fetal cortisol production, or a stress response associated with labor, or a combination of both.