Proof of concept use of progesterone/estradiol ratio to investigate late follicular progesterone in women with low number of preovulatory follicles.

BACKGROUND

The aim of this study was to investigate late follicular progesterone (P) serum levels in women with a low number of preovulatory follicles in the assisted reproductive technologies (ART) setting.

METHODS

Fifty-five consecutive women having four or fewer preovulatory follicles of >14 mm on the day of human chorionic gonadotropin (hCG) administration were prospectively evaluated. Spearman correlation tests were performed between serum estradiol (E<inf>2</inf>) level, serum P level, P/E<inf>2</inf> ratio, number of preovulatory follicles, oocytes and embryos. Women enrolled were further divided into two groups in accordance with the P/E<inf>2</inf> ratio on the day of hCG administration and compared.

RESULTS

Serum E<inf>2</inf> level correlated positively with P serum level (r<inf>s</inf>=0.36, P<0.01), number of mature follicles (r<inf>s</inf>=0.50, P<0.01) and number of oocytes retrieved (r<inf>s</inf>=0.36, P<0.05), whereas negatively with P/E<inf>2</inf> ratio (r<inf>s</inf>=- 0.68, P<0.01). Likewise, number of preovulatory follicles correlated positively with E<inf>2</inf> level (r<inf>s</inf>=0.50, P<0.01), P level (r<inf>s</inf>=0.27, P<0.05) and number of oocytes retrieved (r<inf>s</inf>=0.33, P<0.05), while it correlated negatively with P/E<inf>2</inf> ratio (r<inf>s</inf>=-0.33, P<0.05). Furthermore, women with P/E<inf>2</inf> ratio >1 on the day of hCG administration received considerably higher total follicular stimulating hormone (FSH) dosage and achieved significantly lower number of oocytes and embryos as compared to controls.

CONCLUSIONS

The reverse relationship between number of preovulatory follicles and P/E<inf>2</inf> ratio implies that P rise is not only the result of increased steroidogenic activity, but other oocyte-follicle disrupted mechanisms seem to be involved. An exaggerated FSH stimulation appears to disrupt further these mechanisms.