The impact of oocytes containing smooth endoplasmic reticulum aggregates on assisted reproductive outcomes: a cohort study

Abstract

Abstract Background: The impact of SERa on ART outcomes was still controversial. Our objective is to investigate the impact of the presence of smooth endoplasmic reticulum aggregates (SERa) on ICSI outcomes. Methods: This was a retrospective cohort study. A total of 1,090 fresh ICSI cycles from 944 patients between January 2016 and June 2020 were included. Outcomes from clinical, embryological and neonatal aspects were compared between SERa+ and SERa- cycles as well as between SERa+ and SERa- oocytes. Results: The total gonadotropin (Gn) dose, number of oocytes retrieved, serum estradiol concentration and number of the available embryo were significantly higher in SERa+ cycles than in SERa- cycles (P<0.05). Comparable two pronuclei (2PN) fertilization rate and poly-pronucleus zygote rate were shown in SERa+ and SERa- cycles (P>0.05), but which were higher in SERa+ oocytes than in SERa- oocytes (P<0.05). No statistical difference in blastocyst formation rate was found in SERa+ and SERa- cycles as well as in SERa+ and SERa- oocytes (P>0.05). Good-quality embryo rate was statistically higher in SERa- cycles than in SERa+ cycles (P<0.05), but the difference was comparable between SERa+ and SERa- oocytes (P>0.05). No statistical difference in pregnancy rate, clinical pregnancy rate, spontaneous abortion rate, live birth rate and premature delivery rate were found in SERa+ and SERa- cycles as well as in SERa+ and SERa- oocytes (P>0.05). The implantation rate was comparable in SERa+ and SERa- cycles (P>0.05), but it is higher in the group of only SERa- embryo transfer when compared with the group of mixed SERa+ and SERa- embryo transfer (P<0.05). One hundred and fifty-nine newborns in SERa+ cycles and 140 newborns in SERa- cycles were followed up. Comparable newborn malformation rate was observed between SERa+ and SERa- cycles and oocytes (P>0.05). Logistic regression analysis revealed number of oocytes and total dose of Gn were risk factors for SERa occurrence (aOR=1.05 and 1.55, P<0.001).Conclusion: Oocyte's SERa is correlated with a number of oocytes retrieved and higher Gn dose, but it does not impact pregnancy outcomes and increase newborn malformation rate.