[The dynamics of corticosteroids levels in maternal and fetal plasma]

In order to elucidate the clinical implications of cortisol levels in pregnancy, maternal and fetal serum levels of cortisol during pregnancy were determined. The maternal serum level of cortisol gradually increased with advancing gestational age, and it reached a 3 to 4 times higher level in the late stage of pregnancy than that in non-pregnant state. The maternal serum level of cortisol during delivery increased with the length of the period of labor, and immediately after the delivery it reached the peak value of 60-80 micrograms/dl. According to the mode of delivery, the cortisol level increased with the accumulation of stress on the maternal side. The value was highest in the case of vacuum extraction and lowest in elective cesarean section. The cortisol level in umbilical arterial blood in normal delivery was not significantly elevated in comparison with that in vacuum extraction, oxytocin induced delivery and elective cesarean section. The cortisol level in umbilical blood of anencephaly did not differ from that of normal neonate, indicating that cortisol in umbilical blood may originate mainly on the maternal side. In the postpartum period, the serum cortisol concentration declined to the level observed in the late stage of pregnancy after 2 days, and further decreased to the level in the non-pregnant state after 6 days. The present studies suggest that the increase in the serum concentration of cortisol at delivery is a result of maternal stresses in labor, and that direct involvement of cortisol in the controlling mechanism of puerperium is unlikely. The increased function of the adrenal cortex in the late stage of pregnancy and at delivery may stimulate fetal pulmonary maturity and provide maternal and fetal adaptability to stresses in intrapartum bleeding and shock during labor. It is essential to understand pituitary-adrenal cortex functions in prenatal and fetal care in pregnancy.