Comparison of the C Umulative Live Birth Rates After One ART Cycle Including All Subsequent Frozen–thaw Cycles in Women Undergoing IVF Using Progestin Primed Ovarian Stimulation Versus Long GnRH Agonist Protocol
Authors: Chen Hong , Chen Zhi qin , Ng Ernest Hung Yu , sun zili , wang Zheng , Yao Di , li kunming , Teng xiaoming 
Published: December 2021

Abstract
Background: The efficacy and reproductive outcomes of progestin primed ovarian stimulation protocol (PPOS) were previously compared to rarely used ovarian stimulation protocol and also the live birth rate were reported by per embryo transfer rather than cumulative live birth rates (CLBRs). Does the use of PPOS improve the cumulative live birth rates (CLBRs) and shorten time to live birth when compared to long GnRH agonist protocol in women with normal ovarian reserve?Methods: A retrospective cohort study was designed to include women aged<40 with normal ovarian reserve (regular menstrual cycles, FSH <10 IU/L, antral follicle count >5) undergoing IVF from January 2017 to December 2019. The primary outcome was cumulative live birth rates (CLBRs) within 18 months from the day of ovarian stimulation.Results: A total of 995 patients were analyzed. They used either PPOS (n=509) or long GnRH agonist (n=486) protocol at the discretion of the attending physicians. Both groups had almost comparable demographic and cycle stimulation characteristics except for duration of infertility which was shorter in the PPOS group. In the GnRH agonist group 372 cases (77%) completed fresh embryo transfer, resulting into 218 clinical pregnancies and 179 live birth. The clinical pregnancy rate, ongoing pregnancy, and live birth per transfer were 58.6%, 54.0%, 53.0% respectively. In the PPOS, no fresh transfer was carried out. During the study period, the total number of initiated FET cycles with thawed embryos was 665 in the PPOS group and 259 in the long agonist group. Of all FET cycles, a total of 206/662 (31.1%) cycles resulted in a live birth in the PPOS group versus 110/257 (42.8%) in the long agonist group (OR: 0.727; 95% CI: 0.607–0.871; p<0.001) .The implantation rate of total FET cycles was also lower in the PPOS group compared with that in the agonist group 293/1004 (29.2%) and 157/455 (34.5%) (OR: 0.846; 95% CI: 0.721–0.992; p= 0.041). Cumulative live birth rates after one complete IVF cycle including fresh and subsequent frozen embryo cycles within 18 months follow up were significantly lower in the PPOS group compared that in the long agonist group 206/509 (40.5%) and 307/486 (63.2%), respectively (OR: 0.641; 95% CI: 0.565-0.726). The average time from ovarian stimulation to pregnancy and live birth was significantly shorter in the long agonist group compared to the PPOS group (p<0.01) In Kaplan-Meier analysis, the cumulative incidence of ongoing pregnancy leading to live birth was significantly higher in the long agonist compared in the PPOS group(Log rank test, p<0.001). Cox regression analysis revealed stimulation protocol adopted was strongly associated with the cumulative live birth rate after adjusting other confounding factors (OR =1.917 (1.152-3.190), p=0.012) .Conclusion: Progestin primed ovarian stimulation was associated with a lower cumulative live birth rates and a longer time to pregnancy / live birth than the long agonist protocol in women with a normal ovarian reserve.