Background: The use of progestin (P) during ovarian stimulation is effective in blocking the luteinizing hormone (LH) surge in women with normal ovarian reserve, however, its effects have not been determined in poor responders. This study aimed to explore the follicular dynamics in P-primed minimal stimulation in poor responders.
Methods: A total of 204 infertile women with diminished ovarian reserve were allocated into the medroxyprogesterone acetate (MPA) group or the natural-cycle control group in an alternating order. MPA (10 mg) was administered daily beginning from the early follicular phase and a low dose of hMG was added in the late follicular phase if the serum FSH level was lower than 8.0mIU/ml. When a dominant follicle reached maturity, triptorelin 100 μg and hCG 1000 IU were used for trigger, and oocytes were retrieved 34-36 h later.All viable embryos were cryopreserved for subsequent frozen embryo transfer. Natural cycle IVF was used as controls.
Results: Compared with the natural cycle group, the MPA group exhibited a larger pre-ovulatory follicle (18.7 ± 1.8 mm vs 17.2 ± 2.2 mm), a longer follicular phase (13.6 ± 3.6 days vs 12.3 ± 3.2 days), and higher peak oestradiol values (403.88 ± 167.16 vs 265.26 ± 122.16 pg/ml), while maintaining lower LH values (P < 0.05). The incidences of spontaneous LH surge and premature ovulation decreased significantly (1.0% vs 50%; 2% vs. 10.8%, respectively; P < 0.05). A greater number of oocytes and viable embryos were harvested from the MPA group than from the natural cycle group (P < 0.05). Moreover,the clinical pregnancy rate was slightly higher in the MPA group than in the natural cycle controls, but the difference was not significant (11.8% vs 5.9%, P > 0.05).
Conclusion: This study supported the hypothesis that P-primed minimal stimulation achieved ovulation control of the dominant follicle and did not adversely affect the quality of oocytes in poor responders. Therefore, P-priming is a promising approach to overcome premature ovulation in minimal stimulation for poor responders.
Trial registration: ChiCTR-OCH-14004176 . Registered on January 8, 2014.
Keywords: Natural cycle; Poor responder; Premature ovulation; Progestin.