| Backgroud:Oocyte freezing is an important technology for the preservation of female fertility in assisted reproductive technology,and is widely used by reproductive centers at home and abroad.In the early stages,the commonly used methods of oocyte freezing were mostly slow freezing.With the maturity of vitrification freezing technology,due to its advantages of simple and rapid operation and high survival rate,slow freezing was gradually replaced,and more desirable results were achieved.The use of cryoprotectants during vitrification and the damage of oocytes during cooling and warming are hot topics for scholars to study.There are some relevant literature reports on the effects of cryoprotectants on cell structure and embryonic development potential from the molecular level,while clinical reference also requires meaningful clinical outcomes and offspring follow-up surveys.Due to limited data,there are few relevant reports.Since the implementation of oocyte freezing technology in major centers,it has not only helped couples suffering from tumors and gynecological diseases with the need to delay fertility,but also helped couples unable to produce normal occytes themselves,such as ovarian failure and chromosomal abnormalities,to reproduce normal offspring through oocyte donation.Oocyte donation refers to the fact that couples who have acquired a large number of occytes using assisted reproductive technology.They are willing to donate the remaining occytes to others while ensuring that they have enough available occytes.The source of oocytes is women aged 35 and under.There are two ways to donate oocytes:fresh oocyte donation and frozen oocyte donation.We compared the differences in pregnancy outcomes between different donation methods,the impact of the length of time that oocytes are frozen in liquid nitrogen on the pregnancy outcomes of the recipient oocyte cycle,and the follow-up investigation of offspring born using different freezing solutions to freeze oocytes.The purpose of this study is to help patients to choose occyte donation plans while providing clinicians with reference,avoid excessive reliance on imported reagents,and provide basis for domestic reagent research and development.Methods:The first part collects 252 cycles of frozen oocyte donation(frozen group)and 313 cycles of fresh oocyte donation(fresh group)from 2018 to 2019,and compares the differences between the fertilization rate,2PN cleavage rate,oocyte utilization,and cumulative pregnancy outcome of oocytes during the donation cycle.The frozen group was then divided into 6 groups according to the length of freezing time(within 1 year group,1-2 year group,2-3 year group,3-4 year group,4-5 year group,and more than 5 years group).The survival rate,2PN rate,2PN cleavage rate,D3 high-quality embryo rate,occyte utilization rate,clinical pregnancy rate,survival rate,and postpartum fetal malformation rate of thawed oocytes in each group were compared.In the second part,we screened 131 patients who received frozen oocyte source cycles from 2012 to 2017(with offspring follow-up cycles).We compared patients who used self oocyte freezing solution cryopreserved oocytes(self made group)with patients who used commercial oocyte freezing solution cryopreserved oocytes(commercial group).We followed up the differences between the physical examinations of the two groups of children at the age of 6 months,1 year,and 2 years after delivery,and compared the differences in various auxiliary examination indicators between the two groups of children aged 2-6 years.Fresh oocytes were harvested or frozen oocytes were thawed and cultured in vitro for 2-4 hours before undergoing ICSI insemination.Fertilization was observed for 16-18 hours,and embryo quality was observed and scored 72 hours after fertilization.Superior embryos were selected for transfer,and blood was drawn to examine HCG on the 14th day after transfer.Frozen embryos were transferred after thawing,and blood was drawn to examine HCG on the 12th day after transfer.After pregnancy,progesterone injection continues until 12 weeks,and pregnancy is judged to be a clinical pregnancy when the gestational sac is seen at 7 weeks.Live birth is the birth of a viable newborn.The follow-up children’s examination items include physical examination and blood sampling examination.Results:The fresh group had significantly higher 2PN rate(76.78%,71.25%,P=0.04),2PN cleavage rate(92.38%,99.61%,P<0.01),D3 excellent embryo rate(45.98%,59.46%,P<0.01),and occyte utilization rate(34.03%,44.15%,P<0.01)than the frozen group;However,the cumulative transplantation rate(71.24%,82.54%,P<0.001),cumulative clinical pregnancy rate(58.30%,68.27%,P<0.01),and cumulative live birth rate(43.95%,59.61%,P<0.01)in the cycle were lower than those in the frozen group.There was no statistical difference in the rate of fetal abnormalities between the two groups.After thawing of oocytes in each group for different freezing periods,there was no statistical difference between the fertilization 2PN rate,2PN cleavage rate,D3 excellent embryo rate,blastocyst formation rate,and occyte utilization rate in each group(P>0.05).There was no statistical difference between the clinical pregnancy rate,live birth rate,and postnatal fetal development abnormality rate in each group(P>0.05).There was a statistical difference between the survival rates for different freezing periods(72.00%,84.50%,87.50%,88.44%,91.02%,93.87%,P=0.039).In order to further analyze the specific differences,the survival rates of the adjacent two groups were compared using a Chi square test Except for the group within one year,there was no statistical difference between the results of the other adjacent groups(p>0.05).In the comparison of physical examinations of children aged 6 months,1 year,and 2 years with different frozen oocyte sources,there was no statistical difference between the two groups in the physical examinations of children aged 6 months and 1 year.There was a significant difference in the height of children aged 2 years(89.81±3.41 in the self matched group,86.92±1.89 in the finished product group,P=0.045),and there was no statistical difference in the other items.Except for significant differences in platelet counts(311.51 ± 73.80 in the self made group and 361.78 ±88.11 in the commercial group,P=0.007)in blood tests for children aged 2-6,there were no significant differences in other tests.Compare the proportion of abnormal platelet counts between thetwo groups,and there is no statistical difference,and the average value is within the reference range.Conclusions:In this study,we found that vitrification affects the developmental potential of oocytes,but does not increase with the prolongation of freezing time.There was no significant difference in the health status of delivered infants with different methods of oocyte donation.There were no significant differences in physical development indicators and blood collection assistance tests of postpartum children with different freezing solutions to freeze oocytes. |
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