Characterization of the Reproductive Tract and Gastrointestinal Tract Microbiome and Its Association With Pregnancy Outcomes Following Frozen Embryo Transfer

PURPOSE OF STUDY

To characterize the microbiome of the female reproductive tract and gastrointestinal tract as well as the male reproductive tract in patients and partners undergoing IVF and determine if there are any associations with pregnancy outcomes.

The Clinical Problem

The microbiome of the reproductive tract and its association with reproductive outcomes is a topic of evolving interest. Alterations in the vaginal microbiome have been linked to obstetric complications including miscarriage and preterm birth. More recent data have emerged linking the vaginal microbiome to assisted reproductive technology (ART) outcomes. A prospective observational study consisting of 30 patients who had swabs collected at various time points during the in vitro fertilization-embryo transfer (IVF-ET) cycle for sequencing of the 16S ribosomal RNA gene concluded that the species diversity of the vaginal microbiome distinguished women who had a live birth from those who did not with increased diversity being associated with poorer outcomes; however, the patient population was heterogeneous and small.

Limited information is available regarding the microbiome of the upper genital tract and its association with reproductive outcomes, particularly in the setting of ART. Studies done solely for the purpose of characterizing the upper genital tract microbiome have relied on hysterectomy specimens to assess colonization, thus precluding evaluation of any association with reproductive outcomes. Perhaps the first study to investigate the association between the microbiome of the upper reproductive tract and ART outcomes utilized culture-based technology on embryo transfer catheter tips. However, this study utilized culture-based technology, with only four major bacteria were reported. Subsequent studies have highlighted the limitations of culture-based technology, namely that it is reliant upon successful culture, often resulting in an underestimate of the diversity of organisms.