Importance of progesterone dose regimens for luteal phase support after embryo transfer.

Aim of the study: Luteal phase support with progesterone (P) or human chorionic gonadotrophin has been demonstrated as being necessary in patients undergoing IVF/ET after pituitary desensitization with a gonadotrophin releasing hormone agonist (GnRHa). The objectives of this study were to compare the absorption and the efficacy (implantation and pregnancy rates) of two different dose regimens of P administered vaginally. Methods: Ovarian stimulation was performed with highly purified FSH (Metrodin HP, Serono) after down regulation (Decapeptyl 0.1 mg, Ferring) using a long protocol. The ovulation was induced with 10'000 IU HCG (Profasi, Serono). Forty patients undergoing IVF-ET were prospectively randomized in two groups (n = 20), depending on the dose of micronized P (Utrogestan, Laboratoire Golaz, Switzerland) vaginally administered: group 1, 2 times 200 mg per day; group 2, 2 times 300 mg per day. The main outcome measures were (1) serum estradiol (E2) and P levels during the luteal phase (2, 6, 10 and 14 days after ET); (2) implantation and pregnancy rates (serum HCG and cardiac activity observed respectively 14 and 28 days after ET). Results and conclusions: An equal number of four pregnancies (25% per embryo transfer) and a similar implantation rate (18%) were obtained in each group of patients. Among the non pregnant patients, the decrease of serum P levels during the luteal phase was similar in the two groups, independently of the P dose administered. The serum P levels stabilized ten days after transfer at a level of 30-40 nmol/l which is compatible with the occurrence of a pregnancy. A significant increase of P was observed in seven of the eight pregnant patients between day 6 and 10 after embryo transfer corresponding to the period of implantation.