Effect Of Assisted Reproductive Technology On The Sex Ratio Of Single And Twin Off Spring

In the past few decades,with the rapid spread of assisted reproductive technology(ART),more and more babies have been born through in vitro fertilization(IVF)/intracytoplasmic sperm injection-embryo transfer(ICSI-ET)and the frozen-thawed embryo transfer(FET).It is worth noting that many scholars believe that the sex ratio of babies born through ART are not exactly the same as natural gestation.The second sex ratio(SSR)is the sex ratio at birth,which varies in most populations.However,it is debatable whether the change in the second sex ratio of the ART offspring is a result of natural factor(ie,environmental or biological factor)or an impact of ART.In addition,multiple embryos are often transplanted in ART,which increases the chance of twin pregnancy.Therefore,the SSR of twin births is worthy of further analysis.This study retrospectively analyzed the clinical data of infertile patients who had successful pregnancy after IVF or ICSI treatment and their babies,in order to analyze the potential influencing factors on the sex ratio of single and twin offspring born in ART.OBJECTIVETo explore the effect of ART and individual differences on the sex ratio of single and twin offspring born in IVF or ICSI treatment.MATERIALS AND METHODS1.Objective:We conducted a retrospective cohort study of clinical data from patients who underwent first-cycle IVF or ICSI treatment and successful delivery during the period from 2008 to 2018 at the Reproductive Medicine Center of the Third Affiliated Hospital of Zhengzhou University and their babies.A total of 7863 live births from 6,117 female patients were included in the analysis.2.Methods: The data variables included in the study are offspring gender,age at the time of transplantation for both men and women,female body mass index,type of infertility(primary infertility or secondary infertility),infertility factor(female factor,male factor or mixed factors),promotion protocol(long protocol or other protocol),fertilization method(IVF or ICSI),embryonic stage at the time of transplantation(cleavage-stage or blastocyst embryo),type of embryo(fresh embryo or frozen embryo)and the type of live birth(single or twin).3.Statistics approach: In this study,SSR was defined as the proportion of male live births.All data is stratified by categorical variables.In the Logistic regression analysis model,SSR is used as the dependent variable,and other variables are used as the independent variables.All clinical data were analyzed using SPSS 21.0 software.The measurement data were described in the form of mean ± standard deviation(???x ± s)and the test method used the t test of independent samples.The description of the count data was in percentage(%)and the test method adopts the chi-square test.At the same time,multi-category logistic regression is used to analyze the influencing factors of the second sex ratios of single and twin offspring.If P < 0.05,the difference was significant.RESUITS1.Baseline date comparison: There were no significant differences in women's body mass index,infertility years,infertility type and infertility factors between single and twin groups(P>0.05),while women's age and male age were statistically different between the two groups(P < 0.05).2.A total of 4,211 boys and 3,652 girls were enrolled in the study.In single birth,a total of 4,371 babies were born,including 2,396 boys,accounting for 54.82%.A total of 3,492 babies were born in twins,of which 1815 were boys,accounting for 51.98%.Group comparisons showed that the proportion of boys in singleton pregnancies was higher than that in twin pregnancies(54.82 vs 51.98,P=0.014),and the proportion of boys born in frozen embryos was higher than that of fresh embryos(55.60 vs 52.37,P =0.006),the proportion of boys born in blastocysts was higher than that in cleavage stage embryos(56.17 vs 52.38,P=0.003).3.Multivariate logistic regression analysis showed that in singleton pregnancies,the proportion of boys who were born in other treatments was lower than that of the control group(long protocol)(OR=0.778,95% CI: 0.615-0.985,P=0.037);In contrast,transplantation of cleavage stage embryos reduced the likelihood of boys being born(OR=0.828,95% CI: 0.710-0.964,P=0.015).4.In twin pregnancies,the results show that when the woman's BMI ? 25,the twin girls are more likely to be born(OR=0.703,95% CI:0.511-0.967,P=0.030).CONCLUSIONS1.The ART procedure may have an effect on the second sex ratio of the offspring,and there is a difference in the sex ratio between single and twin pregnancies.2.In the single offspring,the proportion of boys born in the long protocol is higher than that of other protocols.In addition,blastocyst transfer increases the likelihood of a boy's birth.3.In twins offspring,a woman with BMI ? 25 may increase the likelihood of twin girls' birth.