Serum levels of free androstenedione, testosterone and oestradiol are lower in the follicular phase of conceptional than of non-conceptional cycles after ovarian stimulation with a gonadotrophin-releasing hormone agonist protocol.

Serum concentrations of total and free androstenedione, testosterone and oestradiol were followed during the follicular phase in women undergoing ovarian stimulation for treatment by in-vitro fertilization and embryo transfer (IVF-ET) and compared to those in natural unstimulated cycles. In addition, 10 conceptional and 18 non-conceptional cycles were compared in an attempt to understand the background for successful IVF cycles. The ultra-short gonadotrophin-releasing hormone agonist protocol was used for ovarian stimulation. Throughout the follicular phase, levels of total and free androstenedione and oestradiol were significantly lower in conceptional than in non-conceptional IVF cycles. In addition, levels of free testosterone during the follicular phase were significantly lower in women who conceived compared to non-conceptional IVF cycles, whereas levels of total testosterone were similar. Levels of both free and total androstenedione increased significantly from the second day of the menstrual cycle until oocyte retrieval in non-conceptional IVF cycles, whereas levels in conceptional IVF cycles and unstimulated cycles showed no increase. On the day of oocyte retrieval levels of free and total androstenedione were significantly higher in non-conceptional IVF cycles than in conceptional IVF cycles and unstimulated cycles, which were similar. This study suggests that appropriate levels of free biologically active androgens and oestradiol are important parameters for successful conception.(ABSTRACT TRUNCATED AT 250 WORDS)