Development of the hypothalamic-pituitary-adrenal axis in the fetus and preterm infant

Abstract

The development of the hypothalamic-pituitary-adrenal (HPA) axis in the human fetus is a complex process. The feto-placental unit may be responsible for important maturational processes in vital organ systems in the fetus. A late gestational cortisol surge may be important in fetal maturation, particularly maturation of the lungs. Several striking differences exist between the function of the HPA axis in the fetus and in adults, such as a relative deficiency of 3beta-hydroxysteroid dehydrogenase in the fetal adrenal cortex. With the transition from intrauterine to extra-uterine life several changes occur in the function of the HPA axis. In infants born before term, the function of the HPA axis may still be immature at both the central and adrenal level. This immaturity of the HPA axis may be important in the development of neonatal morbidity. The present review describes the development of the HPA axis in the fetus and in preterm infants and discusses the possible role of HPA immaturity in the development of neonatal morbidity.