Enhancing Functional Maturity before Preterm Birth

Enhancing functional maturity of the high-risk preterm fetus is aimed at decreasing the life-threatening neonatal disorders that increase the burden of chronic disease. A course of antenatal glucocorticoids before 35 weeks of pregnancy substitutes endogenous activation of the hypothalamic-adrenal axis that spontaneously enhances functional maturity and augments cytokine-induced preterm lung maturity. It is the main fetal therapy that decreases the functional prematurity-related neonatal morbidity in the era of surfactant therapy. Tocolytic agents potentiate the effect of glucocorticoids on the fetus. Repeating an antenatal glucocorticoid course may be recommended if the preterm fetus remains undelivered for more than 7 days and very preterm birth is imminent. However, the follow-up results are still incomplete, and available preliminary studies warn against adverse neurological and metabolic consequences following several antenatal repeat courses of glucocorticoids. Administration of glucocorticoids after 34 weeks of pregnancy may be considered in selected high-risk cases, preferably with documented lung immaturity. We recommend delaying elective delivery in low-risk pregnancies without established lung maturity until 40 weeks, unless labor starts earlier. In a selected high-risk population 17 alpha-hydroxyprogesterone acetate decreases the prematurity rate. However, this drug has a limited impact on functional maturity of the preterm fetus and its effects on the development of the child remain to be studied further. Copyright (C) 2010 S. Karger AG, Basel