The Association Between Dominant Follicular Proportion And IVF/ICSI Clinical Outcomes

Objective:The mechanism of action,endocrine hormones,and medication regimen differ greatly between different controlled ovarian hyperstimulation(COH)protocols.It is not clear whether their optimal human chorionic gonadotropin(HCG)trigger time is the same.The study was aimed to explore whether dominant follicular proportion(DFP,≥18 mm follicles/≥14 mm follicles)was correlated with oocyte maturation rate,normal fertilisation rate,clinical pregnancy rate and the number of frozen blastocysts in the three main COH protocols.Design and participants:This was a large-sample retrospective cohort study between January 2016 and January 2020 at the Reproductive Medicine Center of Tongji Hospital,Affiliated to Huazhong University of Science and Technology.The inclusion criteria were:patients undergoing in vitro fertilization(IVF)or intracytoplasmic sperm injection(ICSI)for the first time,female with age≤38 years,body mass index(BMI)≤30 kg/m~2,basal serum follicle-stimulating hormone(FSH)<12 m IU/ml,and the number of follicles≥14mm can be counted to be 6-15 via transvaginal ultrasound on HCG day.The exclusion criteria were:donor oocyte cycles/oocyte cryopreservation cycles,and the actual number of oocytes differed from the number of follicles≥14 mm seen via transvaginal ultrasound by more than six.Finally,there were 2 737 cycles of short Gn RH-a long protocol,4 539 cycles of Gn RH-a prolonged protocol,and 2 052 cycles of Gn RH antagonist protocol included.Three groups were divided as follows:Group A:DFP<30%,Group B:30%≤DFP<60%,Group C:DFP≥60%.Pearson’s chi-squared test,one-way ANOVA test,Kruskal–Wallis test,multiple linear regression and binary logistic regression were used to analyze the association between DFP and clinical outcomes(including low oocytes yield rate,oocyte maturation rate,low oocyte maturation rate,normal fertilisation rate,low normal fertilisation rate,clinical pregnancy rate,the number of frozen blastocysts and low number of frozen blastocysts).Results:Compared with Group A,Group B and Group C had a lower risk of low oocytes yield rate(Group B vs Group A:OR=0.626,95%confidence interval:0.500-0.784,P<0.001;Group C vs Group A:OR=0.395,95%confidence interval:0.304-0.513,P<0.001).The results of multiple linear regression and binary logistics regression showed that DFP was not associated with oocyte maturation rate and low oocyte maturation rate(P>0.05).DFP was positively correlated with normal fertilization rate(Group C vs Group A:β=0.017,P=0.021).In addition,with the increase of DFP,the risk of low normal fertilization rate decreased,but the difference was not statistically significant(P>0.05).The clinical pregnancy rate decreased as DFP increased,although it had not yet reached a statistical difference(clinical pregnancy rate for single embryo transfer:Group A vs Group B vs Group C:50.47%vs 47.62%vs 42.76%,P>0.05(short Gn RH-a long protocol);45.54%vs 38.57%vs33.09%,P>0.05(Gn RH antagonist protocol)).The results of logistics regression showed that DFP was not associated with clinical pregnancy.There were significant differences in the number of frozen blastocysts among DFP groups:Group A vs Group B vs Group C:2.93±2.51 vs 2.57±2.29 vs 2.28±2.10,P<0.001(Gn RH-a prolonged protocol);2.67±2.42 vs 2.23±2.21 vs 2.22±2.15,P=0.013(short Gn RH-a long protocol);2.45±2.37 vs 2.11±2.11 vs 1.86±1.95,P=0.003(Gn RH antagonist protocol)).There was a negative correlation between DFP groups and the number of frozen blastocysts(Group B vs Group A:β=-0.198,P=0.001;Group C vs Group A:β=-0.164,P=0.022).Compared with Group A,Group B and Group C had an increased risk of low number of frozen blastocysts(Group B vs Group A:OR=1.207,95%confidence interval:1.053-1.383,P=0.007;Group C vs Group A:OR=1.204,95%confidence interval:1.030-1.408,P=0.020).Interestingly,compared with Gn RH-a prolonged protocol,Gn RH antagonist protocol had a lower risk of low number of frozen blastocysts(Gn RH antagonist protocol vs Gn RH-a prolonged protocol:OR=0.827,95%confidence interval:0.731-0.936,P=0.003).Conclusions:Excessive delay of the HCG trigger and excessive down-regulation may reduce the developmental potential of oocytes,which was related to the occurrence of low number of available blastocysts.But further confirmation by strict prospective randomized controlled study should be needed.