| BackgroundOocyte cryopreservation is an important assisted reproductive technology.With the emergence and development of vitrification cryopreservation technology,the number of oocyte cryopreservation as a fertility preservation method for young women is increasing.However,the validity of oocyte cryopreservation as a fertility preservation technique,as well as the safety of mother and child,still remain controversial.Most studies had explored embryo formation rates,pregnancy rates and live birth rates between frozen and fresh oocytes and reported controversial results.However,there is no clear evidence of differences in the perinatal and neonatal outcomes following in-vitro fertilization using frozen or fresh oocytes.In order to explore whether frozen oocytes and fresh oocytes will lead to different perinatal and neonatal outcomes after in-vitro fertilization,and exclude the influence of ovarian over-stimulation in the process of hyperovulation on pregnancy outcomes,we selected the population of receiving donor oocytes as the study population,and adopted retrospective analysis method to investigate the differences of perinatal complications and neonatal outcomes between donated fresh and frozen oocytes.ObjectiveThe objectives of this retrospective cohort study were to investigate whether there are differences in perinatal and neonatal outcomes between those who received donated frozen and fresh oocytes.MethodsThis retrospective cohort study evaluated 350 donor oocyte cycles from January 2008 to December 2021 at the Center for Reproductive Medicine affiliated to Shandong University,in which 101 used donated fresh oocytes and 249 used donated frozen oocytes.SPSS 25.0 software was used for data analysis in this study to compare the birth weight as well as the incidences of obstetrical complications between singleton pregnancies from donated fresh oocytes(i.e.the fresh-oocyte group)and those from donated frozen oocytes(i.e.the frozen-oocyte group).Mann-Whitney U test,Chi-square test or Fisher’s exact test were used for comparison between groups.Multiple linear regression analysis and binary logistic regression analysis were used to further analyze the relationship between the types of donated oocytes and clinical pregnancy outcomes,controlling for confounding factors.ResultsThere were no significant differences in the frozen versus fresh oocytes group of gestational diabetes mellitus(7.2%vs.11.9%,P=0.159),hypertensive disorders of pregnancy(12.0%vs.17.8%,P=0.155)and placental abnormalities(12.9%vs.19.8%,P=0.098).After adjustment for confounders,birth weight was significantly higher in the frozen versus fresh oocytes group(P=0.023).The gestational age at birth in the frozen-oocytes group was significantly longer than the fresh-oocytes group(275.00 days[IQR,269.00 days,279.60 days]vs.272.00 days[IQR,266.00 days,278.00 days],P=0.027).When the analysis was restricted to frozen embryo transfer cycles,the between-group differences in birth weight and gestational age at birth remained.Subgroup analysis showed that birth weight in the frozen-oocytes group was also significantly higher than that in the fresh-oocytes group(3500g[IQR,3000g,3700g]vs.3300g[IQR,2930g,3500g],P=0.029).The gestational age at birth of the frozen-oocytes group was significantly longer than that of the fresh-oocytes group(276.00 days[IQR,271.00 days,281.00 days]vs.272.00 days[IQR,266.00 days,278.00 days]P=0.004).ConclusionThis study confirmed an association of donated frozen oocytes and increased birth weight as well as longer gestational age of newborn.We found no effect of donated frozen versus fresh oocytes on obstetrical complications.Overall,oocyte cryopreservation technique is relatively safe.But our study was small sample size,larger studies are still needed to further confirm our findings. |
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