[Role of embryonal steroidogenesis in early pregnancy]

Recent studies, have shown that pre-implanted embryos of several species synthesize steroid hormones: progesterone, progestins , androgens and several estrogens and it has been postulated that oviductal and endometrial functions are influenced by blastocyst synthesis and release of these molecules. Steroids may create an appropriate milieu for blastocyst migration, nutrition, development and implantation in the maternal uterus. It is the purpose of this paper to review a possible physiological role of steroid hormonal synthesis by the early embryo during the first stages of pregnancy.