Effects of induced hyperprolactinemia on in vitro fertilization cycles

To investigate the effect of induced endogenous hyperprolactinemia on the luteinization process, as expressed by the shift in the P:E2 ratio after hCG injection in IVF cycles.

Serum PRL, E2, and P levels were measured in 49 IVF patients (leuprolide acetate and hMG protocol) on the day of hCG injection. Estradiol and P also were measured on the day after hCG. Serum P:E2 ratios were calculated for two groups of patients; group I (control): PRL < or = 20 ng/mL (conversion factor to SI unit, 1.00); group II (hyperprolactinemia): PRL > 20 ng/mL. Estradiol and P also were measured in follicular fluid (FF) and the gamete performance was compared between groups.

Data analysis showed no significant differences in the mean +/- SD serum peak E2 (pg/mL; conversion factor to SI unit, 3.671) between groups: group I, 1,769 +/- 843; group II, 2,333 +/- 1,194; the mean FF E2 (pg/mL) group I, 351 +/- 221; group II, 370 +/- 186; or the mean FF P (ng/mL; conversion factor to SI unit, 3.180) group I, 8,357 +/- 3,127; group II, 11,354 +/- 12,888. No significant differences were found between groups in the P:E2 ratios on days 1 or 2: group I, 78 +/- 48 and 209 +/- 137; group II, 70 +/- 47 and 224 +/- 197, respectively. The magnitude of the P shift also showed no significant difference between the two groups; the mean +/- SD shift in the P level was 2.9 +/- 2.2 for group I, and 4.3 +/- 5.1 for group II. The serum PRL level had no effect on the fertilization rate (60% for group I and 70% for group II) or on the pregnancy rate (17% for group I and 23% for group II).

These findings suggest that mild endogenous hyperprolactinemia induced by ovarian stimulation does not affect granulosa cell luteinization and gamete performance in humans.