This retrospective study included 603 DOR patients undergoing ICSI treatment cycles stimulated with a standard antagonist and luteal E2 priming antagonist protocols between January 2007 and July 2019. The study protocol was approved by the Etlik Zubeyde Hanim Women’s Health Training and Research Hospital Local Ethics Committee (2019/209). Patients with at least two of the following were diagnosed as DOR: 1) basal serum follicle-stimulating hormone (FSH) level ≥12 IU/L and estradiol (E2) level >80 pg/ml measured within the last three months of the IVF cycle, 2) AFC <7 , 3) serum antimullerian hormone (AMH) level <1.1 ng/ml measured in 6 months. Severe male factor infertility, indication for pre-implantation genetic diagnosis (PGD), freeze and thawed embryo cycles, presence of chromosomal or autoimmune disorders, endocrine or metabolic disorders (such as diabetes, hypo/hyperthyroidism, and hyperprolactinemia) were the exclusion criteria.
Demographic characteristics, such as age, body mass index (BMI), number of previous IVF cycles, duration of infertility, and basal characteristics (AFC, AMH measurement, serum basal FSH, E2, luteinizing hormone (LH) levels) were recorded. Groups were compared in terms of duration of ovulation induction, total gonadotropin dose used, E2 and progesterone (P) levels and endometrial thickness on hCG day, the number of retrieved oocytes, mature oocytes, an fertilized oocytes. The number of embryos (good or poor quality) transferred and the E2, P levels, and endometrial thickness on the transfer day were also analyzed. The number of embryo transferred cycles, the number of canceled cycles, day of embryo transfer (day 3 or day 5), biochemical pregnancy, clinical pregnancy, and live birth rates per ET were compared between the groups.
In the standard flexible GnRH antagonist protocol, gonadotropin was initiated on day 3 of the menstrual cycle. The patients received gonadotropins with the starting dose of 225-450 IU/day using recombinant FSH (recFSH; Gonal-F, Merck-Serono, Istanbul, Turkey or Puregon; Organon, Istanbul, Turkey) with human menopausal gonadotropin (hMG; Menagon; Ferring, Istanbul, Turkey or Merional; IBSA, Istanbul, Turkey). The dose was determined based on age, BMI and AFC and tailored according to follicular development. When the mean diameter of ≥ two follicles reached 13-14 mm during stimulation, the antagonist was initiated (Cetrotide, Merk-Serono, Istanbul, Turkey) and was continued until the recombinant human chorionic gonadotrophin (rechCG) administration day.
Luteal phase estradiol priming protocol
The patients in the luteal E2 priming protocol group received oral E2 hemihydrate (Estrofem, Novo-Nordisk, Istanbul, Turkey) twice a day, beginning on day 21 of the previous cycle until the first day of menses. The gonadotropins (recFSH and hMG) were initiated on day 3 of the menstruation similar with the standart antagonist protocol and when ≥two follicles reached 13-14 mm in diameter, the antagonist, Cetrotide, was initiated and continued until the rechCG administration day.
Ovarian response was monitored by serial transvaginal ultrasound and serum estradiol and LH assessments. Rec hCG of 250 mg (Ovitrelle, Merck-Serono, Poland) was administered to all subjects for the final oocyte maturation when at least three follicles reached a diameter of 18 mm. Transvaginal oocyte retrieval (OPU) was performed 35.5-36 hours after hCG administration, and intracytoplasmic sperm injection (ICSI) was performed for all mature oocytes. The presence of two pronuclei 18-20 hours following ICSI confirmed the fertilization. The absence of fertilization was defined as total fertilization failure (TFF). The embryo development was assessed daily, and a development arrest for 24 hours or the presence of an embryo with all cells degenerated or lysed were accepted as embryo development arrest (EDA).
No follicular development with ovarian hyperstimulation, no oocytes retrieved in OPU, and presence of TFF and EDA were considered as cycle cancellation.
The embryo transfer was performed on day 3 or 5 with ultrasonography guidance. Luteal phase support was provided to all patients with the combination of intramuscular (Progestan amp, Koçak Farma, Turkey) and vaginal progesterone (Crinone 8% gel, Merck-Serono, UK). A positive pregnancy test was diagnosed by β-hCG levels in blood tests performed 14 days after OPU. Clinical pregnancy was defined by the presence of an intrauterine gestational sac with fetal cardiac activity by transvaginal ultrasonography. Spontaneous abortion is defined as the loss of a nonviable pregnancy up to 20 weeks of pregnancy. Live birth was defined as the delivery of a viable fetus after 24 weeks of gestation.
The primary outcomes were clinical pregnancy rate per ET, live birth rate per ET, and the cycle cancellation rate. The secondary outcomes were the number of retrieved oocytes, mature oocytes and the number of embryos transferred.
Statistical analyses were performed using the SPSS Windows version 23.0 (SPSS Inc., Chicago, IL). The distribution of the continuous variables, coefficients of skewness, and kurtosis were checked using the Kolmogorov Smirnov test and ve histogram. Continuous variables were defined with mean ± standard deviation, and categorical variables were defined with frequencies and numbers (%). Mann-Whitney U test was used to evaluate comparison between non-normally distributed continuous variables and two-level variables. The Chi-square test was used to evaluate categorical variables. A value of p < 0.05 was accepted as statistically significant.