Hormone replacement for pregnancy in functionally agonadal women after transfer of thawed embryos in the in vitro fertilization program--problems of placental incompetence

Experience with hormonal substitution of sterile women treated within the IVF programme by means of donated oocytes changed completely views on endocrinological prerequisites of successful implantations and the further development of early pregnancy. While the effect of oestrogens and progesterone on endometrial proliferation and receptivity has been elaborated in great detail in the literature, data on the substitution of early pregnancy and the onset of placental competence are much scarcer. 1. The placenta is during the 15th week of pregnancy already fully competent and hormonal substitution can be probably terminated already sooner. 2. From the shape of the curves (as compared with steroid levels in spontaneous pregnancies) the authors conclude that the used doses (in particular of progesterone were higher than physiological. 3. Pregnancy of women with primary or secondary ovarian failure is an ideal in vivo model for investigation of the receptivity of the endometrium, the problem of implantation and function of the foetoplacental unit. Available data are not uniform and therefore in this very interesting field further investigations are needed.