Comparison of starting ovarian stimulation on day 2 versus day 15 of the menstrual cycle in the same oocyte donor and pregnancy rates among the corresponding recipients of vitrified oocytes

Objective To assess the clinical pregnancy rate per transfer in recipients of embryos from donor oocytes obtained after ovarian stimulation initiated on day 2 (D2) or day 15 (D15) of the menstrual cycle with a secondary end point of comparing the response to stimulation. Design Prospective observational comparative study. Setting Private in vitro fertilization (IVF) program. Patient(s) Oocyte donors (OD) and recipients. Intervention(s) Donors stimulated within 3 months, starting on day 2 or day 15 after bleeding, with recombinant follicle-stimulating hormone (FSH), gonadotropin-releasing hormone (GnRH) antagonist, and GnRH agonist trigger, and oocytes vitrified and later assigned to recipients, followed by routine IVF procedures one to two embryos transferred. Main Outcome Measure(s) Primary outcome pregnancy rate, and secondary outcome number of mature oocytes retrieved. Result(s) Nine D2 and nine D15 cycles were performed in nine donors. There were no differences between D2 and D15 in the number of mature oocytes obtained (14.0 ± 6.96 vs. 16.89 ± 7.52). To date, 20 recipients have received vitrified oocytes (8 recipients received D2 oocytes and 12 recipients received D15 oocytes). There were no differences between the groups of recipients in fertilization rate (77.3% vs. 76.5%) or number of embryos transferred (1.50 ± 0.53 vs. 1.67 ± 0.65). Twelve clinical pregnancies were obtained. No differences were noted in pregnancy rates (62.5% vs. 58.3%) or implantation rates (41.67% vs. 45%) between recipients of D2 oocytes and recipients of D15 oocytes. Conclusion(s) Donor oocytes obtained after ovarian stimulation initiated on day 15 of the cycle achieve good pregnancy rates. This information is useful for patients with cancer undergoing fertility preservation. Clinical Trial Registration Number NCT 01645241.