Hormonal modulation of fetal pulmonary development: relevance for the fetus with diaphragmatic hernia.

Antenatal hormonal modulation of pulmonary growth has been successfully introduced in clinical practice to reduce the incidence of respiratory distress syndrome (RDS) of preterm born infants. However, a certain amount of reserve to repeat courses should be taken into account because of possible adverse effects of antenatal administration of glucocorticoids. Although in experimental animals thyroid hormones given alone were not shown to have stimulatory effects on pulmonary development, there was an apparent synergistic effect with corticosteroids. Yet, such effects have not been substantiated in clinical trials. Whereas in cases of congenital diaphragmatic hernia (CDH) in utero tracheal occlusion could stimulate fetal lung growth and modulation, the enhancement of type II cell differentiation is more likely to be achieved with antenatal exposure to hormonal therapies. However, there is still no firm scientific basis for either of these two treatment modalities in CDH. Yet, antenatal hormonal modulation is now soon to be tested in an extensive multi-center clinical trial. In this review, the current status of antenatal hormonal modulation of pulmonary growth will be described and its potential role in the treatment of CDH will be discussed.