| BackgroundIn China mainland,a common situation for oocytes vitrification is to preserve supernumerary oocytes for future use in IVF/ICSI cycles with more than 15 oocytes are retrieved.In a cycle with excessive oocyte retrieval(>18-20),vitrified a small number of oocytes(≥3)is in consideration that the patient can obtain the highest probability of pregnancy for a single cycle with the remaining fresh oocytes.A concern for both the patients and clinicians is whether it is valuable to use the remaining cryopreserved oocytes in cases of failure of plenty fresh oocytes from the same retrieval cycles,and whether these oocytes are less efficiency or less safe than the oocytes frozen for other indications.ObjectiveTo compare IVF/ICSI cycles with vitrified oocytes of different indications,to assess the effectiveness and safety of utilizing the small number of remaining vitrified oocytes after the failure of adequate fresh sibling oocytes,and to clarify the value of the "cryopreservation of small numbers of oocytes" strategy for patients.MethodsThis respective cohort study extracted data of all autologous IVF/ICSI cycles using oocytes that had been vitrified in the Reproductive Hospital affiliated to Shandong University from January 2013 to December 2019.All the cycles were divided into three groups according to the indications of oocyte vitrification.Among them,429 cycles vitrified oocytes owing to infertile couples acquired excessive oocytes(supernumerary oocytes cryopreservation,SOC group),90 cycles with an inability to provide an ejaculated sample through masturbation or unexpected absence on oocyte retrieval day(relative male factor-oocyte cryopreservation,relative-MOC group),and 272 cycles with unavailable or insufficient sperm from an ejaculated sample or surgical collection on oocyte retrieval day(absolute male factor-oocyte cryopreservation,absolute-MOC group).Comparisons between the three groups were performed using statistical methods such as logistic regression analysis and Kaplan-Meier analysis.Results1.Baseline characteristics of the three groups:There were significant differences in age,BMI,basal hormones,ovulation stimulation protocols,the number of oocytes retrieved,the number of vitrified oocytes,and preservation duration between the three groups.After fresh oocytes were transferred to fresh embryos,there was no statistical difference in clinical pregnancy rate,early abortion rate and live birth rate among the three groups.2.The laboratory and pregnancy outcomes of oocyte warming cycles:The oocyte survival rate of SOC group was better than absolute-MOC group(88.95%vs 84.99%,p<0.001),however there was no difference between SOC and relative-MOC groups(88.95%vs 84.17%,p=0.329).The D3 high-quality embryo rate was higher in absolute-MOC group than SOC group(31.22%vs 23.68%,p<0.001).The cumulative probability of live birth rate(CPLB)was highest in absolute-MOC group,and lowest in SOC group(39.0%vs 28.9%,p=0.006).3.Multivariate logistic regression analysis of cumulative probability of live birth:There was no correlation between indications for oocyte vitrification and CPLB.the CPLB improved when more oocytes were consumed and the older patients(>35)has a lower CPLB than younger patients.4.Perinatal and neonatal outcomes of oocyte warming cycles:There was no differences in the rates of gestational diabetes mellitus,hypertension during pregnancy,cesarean section,newborn gender,birth weight,gestational age,and congenital defects after fresh embryo transfer(ET)and freezing embryo transfer(FET)between the three groups.Conclusion1.When scanty live births were from fresh oocytes,a relatively ideal CPLB can still be obtained from the remaining vitrified oocytes.2.The CLBR of vitrified oocytes for different indications was correlated with age and number of warmed oocytes.3.The strategy of cryopreserved a small part of oocytes is recommended when plenty oocytes are retrieved,for it could benefit most women by preserving fertility at different levels. |
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