Abstract
In vitro fertilization (IVF) is an important assisted reproductive technology in treating infertility, whose failure rate is still high. Studies suggested that uterine microbiota are related to women’s reproductive diseases and persisting intrauterine bacterial infectious conditions, such as chronic endometritis (CE), impairing the pregnant processes. However, the relationship between uterine microbiota and IVF outcomes is still an open question. In the present study, 94 patients diagnosed with infertility were enrolled and were divided into CE (E group, n = 25) and non-CE (NE group, n = 69) groups depending on the hysteroscopy and immunohistochemistry. Subsequently, E (Ep, n = 8 and Enp, n = 17) and NE (NEp, n = 41 and NEnp, n = 28) groups were divided into pregnancy and non-pregnancy groups depending on the IVF outcomes, respectively. The uterine fluids were collected and microbial profiles were examined through the V4 region of 16S rRNA gene high-throughput sequencing. The results demonstrated that patients with CE had significantly lower clinical pregnancy rate compared with the non-CE patients (32 vs. 58.42%, p = 0.0014). The relative abundances of Proteobacteria and Acidobacteria were higher in the non-CE group, whereas high abundances of Actinobacteria and Fusobacteria were observed in the CE group at the phylum level. At the genus level, high relative abundances of Gardnerella were observed in the CE group and non-pregnancy groups, which significantly referred to the negative IVF outcome. In conclusion, CE may be a key factor for the negative outcome after IVF, of which the uterine microbiota plays a pivotal role, and the microbial diversity in uterine may serve as a biomarker to forecast the success of IVF outcome.
Highlights
Infertility is defined by failure to establish a clinical pregnancy after 12 months of regular and unprotected sexual intercourse, and in vitro fertilization-embryo transfer treatment (IVF-ET) is increasingly being used in treating it (Vander Borght and Wyns, 2018)
The clinical pregnancy rate in the chronic endometritis (CE) group was significantly lower than the non-CE group (p = 0.0014)
Our results demonstrated that the relative abundance of Proteobacteria was higher in the non-CE group and successful pregnancy groups, which indicated that Proteobacteria is a beneficial bacterium
Summary
Infertility is defined by failure to establish a clinical pregnancy after 12 months of regular and unprotected sexual intercourse, and in vitro fertilization-embryo transfer treatment (IVF-ET) is increasingly being used in treating it (Vander Borght and Wyns, 2018). The microbial communities of the female reproductive tract have gradually become well known in pathological shifts affecting the reproductive processes, including fertilization, implantation, maintenance of pregnancy, and microbial colonization of the newborn, and are responsible for other gynecological conditions thanks to next-generation sequencing (Franasiak and Scott, 2015; Skafte-Holm et al, 2021) This adds a new microbiological dimension to human reproduction, which opens a new microbiological field in female reproductive conditions (Franasiak and Scott, 2015; Campisciano et al, 2020; Riganelli et al, 2020). The study of uterine microbiota was still limited by the vaginal contamination and low biomass, and limited study focused on the association of uterine microbiota and the IVF outcomes highlighting the healthy and unhealthy microbial compositions
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