Betamethasone was selected as pre-treatment for CD34+ experimental transplantation for two reasons: (1) it is a commercially available and safe synthetic glucocorticoid used in the late phase of pregnancy to prevent respiratory distress syndrome in pre-term newborns (Sweet et al. 2019), and (2) glucocorticoids are involved in the ontogeny of the fetal immune system and other organs. This evidence concerns the gene CD34 and newborn respiratory distress syndrome.