This was a retrospective analysis including PCOS women who performed their first artificial reproductive technology (ART) cycle with PPOS protocol or GnRH-antagonist protocol in our centre from July 2013 to June 2018. The cycles were followed to February 2020.The objective of this study was to compare cumulative live birth rate of PPOS protocol and GnRH-antagonist protocol. The study was approved by the institutional ethics committee of The First Affiliated Hospital of USTC.
PCOS was diagnosed according to Rotterdam consensus as fulfilling at least two of the three criteria: 1) oligo-anovulation or anovulation;2) clinical or biochemical signs of hyperandrogenism; and 3)polycystic ovarian morphology on ultrasound, as defined by at least one ovary with ＞12 follicles or volume ＞ 10 cm3. Exclusion criteria were: other causes of hyperandrogenism and ovulation dysfunction; patients＜20 or >40 years of age at oocyte retrieval; history of recurrent miscarriage; congenital uterine malformations; abnormal chromosome karyotype, preimplantation genetic diagnosis (PGD) cycles, no embryo transferable cycles.
GnRH antagonist protocol
Recombinant FSH (Gonal-f; Merck Serono, Geneva, Switzerland) was started on Days 2–3 of the progesterone induced or spontaneous menstrual cycle and continued until the day of ovulation induction. The initiation doses will be 112.5 IU/day for patients weighing ≤60 kg and 150 IU/day for patients weighing >60 kg. At day 5-6 of ovarian stimulation, the rFSH doses were adjusted according to ovarian response evaluated by transvaginal ultrasonography and serum hormone tests. GnRH antagonist (Cetrorelix; Merck Serono, Darmstadt, Germany) at a daily dose of 250μg was started when the largest follicle exceeded 12 mm. Recombine human chorionic gonadotropin (r-hCG) 250ug (Ovitrelle; Merck Serono, Geneva, Switzerland) was administered to trigger oocyte maturation when two or more follicles were ≥18 mm. If the patients were at highly risk of ovarian hyperstimulation syndrome (OHSS) (over 16-18 follicles were >11 mm diameter on the day of triggering), ovulation triggering was performed either by administration of triptorelin 0.2 mg (Decapeptyl, Ferring Pharmaceuticals, Netherlands) or by triptorelin 0.2 concomitant with 1000 IU of hCG. In that case, “freeze-all” strategy was applied.
Ovarian stimulation was initiated on menstrual cycle Day 2-3 with daily injection of r-FSH (Gonal-f; Merck Serono, Geneva, Switzerland) combined with oral MPA (6-8 mg/d, Shanghai Xinyi Pharmaceutical Co., China). The initiation doses was 112.5 IU/day for patients weighing ≤60 kg and 150 IU/day for patients weighing >60 kg also. After 5 days of stimulation, transvaginal ultrasound scans and serum hormone tests will be performed to adjust FSH doses. When three dominant follicles reached 18 mm in diameter, the final stage of oocyte maturation was co-triggered by triptorelin 0.2 mg (Decapeptyl, Ferring Pharmaceuticals, Netherlands) and hCG 1000 IU ( Lizhu Pharmaceutical Trading Co., China).
Transvaginal ultrasound–guided oocyte retrieval was performed 34–36 h after trigging. Collected oocytes were inseminated either via conventional IVF or ICSI. Embryos were examined on Day 3 after insemination. Two good-quality embryos (including grade 1 and grade 2 6-8-cell embryos) were frozen by vitrification on the third day after oocyte retrieval. Surplus embryos were placed in extended culture to day 5 or day 6. Embryos were graded as 1(good), 2(reasonable), or 3(moderate) according to the number of cells, degree of fragmentation and renewed development of the embryo. This standard was based on the ESHRE Istanbul consensus on embryo assessment . Only grade 1-3 blastocysts were frozen. The laboratory procedure of vitrification and warming for Day 3 embryos was the same as the method used for human oocytes reported by Tong et al . For blastocysts, a glass micro-needle was used to collapse the blastocyst before vitrification. The following steps were the same as for the Day 3 embryos.ET was performed under ultrasound guidance. Intravaginal progesterone gel (Crinone gel 8%, Serono) was administered for luteal phase support from the day after oocyte retrieval until 8-10 weeks of pregnancy.
In order to ensure validation of complete cycles, this study only involved patients who had already used all their frozen embryos from the present oocyte retrieval or gave live birth to a child.
Fresh embryo transfer
Fresh ET was intended for the patients triggering with hcg and no signs of early OHSS in GnRH antagonist protocol. OHSS was diagnosis according to the guideline of Practice Committee of the American Society for Reproductive Medicine .
Frozen–thawed embryo transfer
‘Freeze-all’ strategies were applied in PPOS group. For patients triggering with in triptorelin or at high risk of OHSS in GnRH antagonist group, ‘Freeze-all’ strategies were also applied. In this study, endometrium preparation method of FET was the same in the two groups. In brief, hormone replacement treatment cycle or letrozole-induced- ovulation cycle was choose based on the discretion of physicians and/or patients’ preference. In letrozole -induced- ovulation cycle, letrozole 5 mg was administered for 5 days, and then, follicle growth was monitored beginning on day 10. If no dominant follicles were found, a low dose of HMG (75 IU/day) was used to stimulate follicle growth and endometrial lining.Day-3 ET was performed 4 days after spontaneous or hCG-induced LH surge while blastocyst transfer was performed 6 days after spontaneous or hCG-induced LH surge. In hormone replacement treatment cycle, estradiol valerate (progynova, Schering, German) was taken 6 mg/d from menstrual cycle day 2-3. An ultrasound assessment was done 12 to 14 days later to assess endometrium thickness. Progesterone 40 mg/d，which would be changed to 60 mg/d 2 days later, was given to transform the endometrium, provided the endometrial thickness exceeded 8 mm. Embryo transfer was performed 4 days after progesterone administration for day-3 embryos or 6 days later for blastocysts.
Main outcome measure and statistical analysis
The primary outcome was the CLBR defined as the delivery rate of a live infant (>24 weeks of gestation) in fresh or subsequent FET cycles in relation to one oocyte retrieved. Only the first delivery was considered in the analysis.
All analyses have been performed using IBM Spss statistics 21.For continuous variables, Student’s t-test and Mann–Whitney test were used for data with homogeneous variance and heterogeneous variance respectively. The x2 test was used for categorical variables. Logistic regression analyses were conducted to identify independent correlates between each possible confounding factor, especially treatment protocol and cumulative LBR after adjusting for other confounders that were identified in our univariate analysis. P<.05 was considered statistically significant.