Potential Contribution of the Uterine Microbiome in Early Missed Abortion

Abstract

BackgroundMissed abortion is a kind of pregnancy failure caused by various reasons. The etiology is complicated, and the incidence of miscarriage is increasing in recent years. Previous studies shown microbiota contributes to multi-systemic function, whereas the relationship between microbiota and early missed abortion remains unknown. This study aimed to explore the composition of uterine microbiota in missed abortion and the potential role.MethodsWe enrolled 19 patients diagnosed with missed abortion and 12 healthy pregnant who subsequently had 6-8th week pregnant. All samples were taken from the endometrial fluid by a special disposable endometrial sampler. After samples were collected, DNA was extracted and amplified. The high-throughput next-generation sequencing (MiSeq) of the 16S rDNA V3-V4 region was used to identify the present of microbiota. The α-diversity of microbiota data was used to reflect species richness and evenness within bacterial populations, β-diversity was used to reflect the shared diversity between bacterial populations, and Nonmetric Multidimensional Scaling based on Weighted Unifrac distance. Statistical was determined by use of multiple testing, including the generalized mixed-effects model.ResultsThe microbiome sequencing (16S rDNA V3-V4 region) revealed that low abundance microbiome was detected in uterine cavity of patients with missed abortion and normal pregnancy. The diversity of intrauterine microflora in patients with missed abortion was higher than that in patients with induced abortion in normal pregnancy. There was no significant difference in alpha diversity between the two groups, but a significant difference was observed in beta diversity. PCoA moment array analysis did not show significant differences. Proteobacteria and Firmicutes in missed abortion patients were significantly more than those in normal pregnancy group.ConclusionThere are low abundance of microflora in uterine cavity of missed abortion patients, and the diversity of microflora is higher than that of normal pregnancy patients. Also, Proteobacteria and Firmicutes may be potential biological markers in missed abortion. New observations may prompt further investigations to understand the potential mechanism of microbiology on pathologic human pregnancy in the future.SubjectsMicrobiology, Molecular Biology, Gynecology and Obstetrics, missed abortion, Female Reproductive Tract,