Comparison of fixed and flexible progestin-primed ovarian stimulation protocols to prevent premature luteinization in patients with diminished ovarian reserve.

PURPOSE: Flexible progestin-primed ovarian stimulation (PPOS) protocol is demonstrated to be effective in suppressing premature luteinization in few studies. We aimed to compare fixed and flexible PPOS protocols in preventing premature luteinization in patients with diminished ovarian reserve.

METHODS: This retrospective cohort study included patients with a diminished ovarian reserve who were administered PPOS protocols for pituitary suppression during ovarian stimulation in a tertiary center in between January 2019 and June 2022. At fixed protocol, 20 mg/day dydrogesterone was started in cycle day two or three along with gonadotropins and continued until trigger day. In contrast, at flexible protocol, 20 mg/day dydrogesterone was commenced when the leading follicle reached 12 mm or serum estradiol (E2) level was > 200 pg/mL.

RESULTS: A total of 125 patients, of whom 83 were administered fixed PPOS protocol and 42 were administered flexible PPOS protocol, were included in the analysis. Both groups had similar baseline characteristics and cycle parameters, including total days of gonadotropin administration and total gonadotropin dose (p > 0.05). Premature luteinization occurred at 7.2% and 11.9% of patients in fixed and flexible PPOS protocols, respectively (p = 0.505). Retrieved oocytes numbers, metaphase II oocyte numbers, and 2PN numbers were also similar (p > 0.05). Clinical pregnancy rates per transfer were 52.5% in fixed and 36.4% in flexible protocols (p = 0.499).

CONCLUSION: Both fixed and flexible PPOS protocols had statistically similar outcomes in preventing premature luteinization and other cycle parameters. The flexible PPOS protocol seems to be as effective as the fixed PPOS protocol for patients with diminished ovarian reserve; however, further prospective studies should be conducted to validate the results of our research.