The variation of serum cortisol during ovarian stimulation for in vitro fertilization.

Aim: As there is no consensus concerning the variation of serum cortisol level during in vitro fertilization (IVF), we studied it prospectively by frequent evaluation throughout the course of an IVF cycle and compared the value, as control, of cortisol concentration obtained in the previous month (M-1) with the concentration obtained on the first day (D1) of ovarian stimulation.

Methods: In 23 IVF cycles using gonadotropin-releasing hormone agonist/human menopausal gonadotropins (hMG)/human chorionic gonadotropin, cortisol and estradiol were measured at M-1, D1, day 14 (D14, before beginning hMG), day 16 (D16), day 19 (D19), day 22 (D22), day 24 (D24), the day before (T-1) and the day after triggering ovulation (T+1), the day of oocyte retrieval (OR), 15 days after embryo transfer (ET+15) and the next month (M2). Statistical analysis used tests of linear tendency, the Pearson chi(2) test, analysis of variance, Student's t test and Spearman correlation.

Results: Cortisol was non-significantly lower at M-1 compared with D1; although remaining in the normal range, mean cortisol increased progressively after D1, in a manner unrelated to estradiol, with non-significant differences between different time points but a significant linear tendency and a maximum value at T+1. All mean cortisol values were significantly higher than that at M-1 and, except for D19 and T-1, D1. Mean cortisol decreased at ET+15 and significantly at M2, the value at M2 being lower than that at M-1.

Conclusion: Cortisol showed a progressive increase beginning from D1, especially after ovulation triggering, and returned to pre-treatment level next month. Cortisol variation was not related to the changes in the E(2) values. Cortisol values at both M-1 and D1 could be used as controls.