Whether Vaginal Microbiota Affects Pregnancy Outcomes After Embryo Transfer

Despite clinicians' efforts to optimize clinical protocols in assisted reproduction, the clinical pregnancy rate continues to be unsatisfactory. Microbial dysbiosis has been implicated in numerous adverse reproductive conditions. The examination of microorganisms remains a promising avenue for improving clinical outcomes following embryo transfer in in-vitro fertilization (IVF) centers.

The vagina serves as the primary barrier, separating the external environment from the upper reproductive tract. Recent studies employing deep sequencing of microorganisms in IVF patients have shed light on the association between the diversity of vaginal microbiota and the abundance of specific microorganisms with crucial reproductive outcomes. However, certain studies have yielded inconsistent results, suggesting either no discernible association between vaginal microbiota and IVF outcomes or varying disparities in bacterial composition between groups with favorable and unfavorable clinical outcomes. Research into predictive models based on reproductive tract microbiota remains relatively limited. Hence, further studies are warranted to elucidate the correlation between vaginal microorganisms and pregnancy outcomes.

The aim of this study is to explore the characteristics of vaginal microbiota in patients undergoing IVF treatment and examine potential differences between those who achieve pregnancy and those who do not. Patients will be asked to complete a questionnaire regarding their basic characteristics, and vaginal secretions will be collected via vaginal swab during frozen-blastocyst transfer procedures. High-throughput sequencing of the V3-V4 variable region of the 16S rRNA gene will be conducted on the vaginal secretions of participants. Specifically, investigators will: (1) compare Alpha diversity between the two groups; (2) compare Beta diversity between the two groups; (3) investigate whether there are any differences in specific bacterial taxa between the two groups; (4) determine the favorable or unfavorable profiles of vaginal microbiota associated with achieving pregnancy; and (5) explore methods for predicting pregnancy outcomes based on vaginal microbiota. This study presents a prospective approach to utilizing microbial characteristics for predicting pregnancy outcomes before implementing further interventions, offering potential refinement of treatment strategies for IVF patients.