The hypothalamic-anterior pituitary-gonadal system of the infant rodent is sensitive to sex hormones. In the female, an increase in androgens leads to improper development of an anovulatory ovary. In the male, an increase in estrogens prevents the testis from attaining normal development. These atrophic testes show serious abnormalities of spermatogenesis and androgen biosynthesis. Progesterone, which may function as both an antiestrogen and an antiandrogen, can prevent these abnormal developmental changes.
It is suggested that a function of progesterone, in pregnancy, may be the defense of the fetus against increased concentrations of androgens and/or estrogens.