In contrast to the former notion of a sterile womb, sequencing techniques have proven a bacterial colonization of the uterus. However, timing of microbiota analysis regarding possible intra-cycle variations as well as specific alterations in patients with recurrent miscarriage (RM) or recurrent implantation failure (RIF) remain unknown. In total, n = 20 RM-, n = 20 RIF-patients and n = 10 healthy controls were included in this prospective study. In every subject, uterine flushing was performed during follicular, ovulatory and luteal phase. Bacterial DNA was isolated and 16S amplicon sequencing analysis of the V3-V4 region was carried out. Diversity measures were compared between samples from the disease groups and the control group separately for each timepoint of the menstrual cycle and over time. In the control group a significant decrease of species richness and evenness was shown around ovulation which remained at this lower level during the luteal phase (Shannon index), indicating a more uniform distribution of microbiota (p < 0.05). This loss of diversity during the menstrual cycle was not apparent in RIF and RM patients. A higher similarity was seen in taxonomic distribution between RM and RIF patients compared to the control group. Longitudinal dynamics included increases in Firmicutes (controls and RM only) and a concomitant loss of Proteobacteria in controls that was not present in RIF and RM. We demonstrate longitudinal intra-cycle-dependent changes in the endometrial microbiota of healthy controls. An increased diversity in both patient groups could be the cause or consequence of a micro-environment that is more prone to pregnancy failures.

与以前的无菌子宫概念相反，测序技术已证明子宫有细菌定植。然而，关于可能的周期内变化以及复发性流产 (RM) 或复发性植入失败 (RIF) 患者的特定改变的微生物群分析时机仍然未知。总共，n = 20 RM-，n = 20 RIF 患者和 n = 10 健康对照被包括在这项前瞻性研究中。在每个受试者中，在卵泡期、排卵期和黄体期都进行了子宫冲洗。分离细菌DNA并进行V3-V4区域的16S扩增子测序分析。在月经周期的每个时间点和随着时间的推移，分别比较来自疾病组和对照组的样本的多样性测量值。在对照组中，排卵前后的物种丰富度和均匀度显着下降，在黄体期（香农指数）保持在这个较低的水平，表明微生物群的分布更加均匀（p < 0.05）。在 RIF 和 RM 患者中，这种在月经周期中的多样性丧失并不明显。与对照组相比，RM 和 RIF 患者之间的分类分布具有更高的相似性。纵向动力学包括厚壁菌门（仅对照和 RM）的增加以及在 RIF 和 RM 中不存在的对照中伴随的变形菌的损失。我们展示了健康对照组子宫内膜微生物群的纵向周期内依赖性变化。