LAUSR

PROBLEM To investigate how asymptomatic bacterial imbalance affects the clinical pregnancy rate after artificial insemination with the husband's semen (AIH). METHODS This study included married heterosexual couples who underwent AIH. According to the follow-up results, participants were divided into the pregnancy and non-pregnancy groups. Based on the first 10 pair participants in each group with vaginal flora bacterial 16S rRNA sequencing results, six semen samples received bacterial-sperm mixed test. Moreover, 34 cytokines were detected in the peripheral blood sera of the first 3 pairs by high-throughput Luminex, which were verified in vaginal secretions, cervical mucus and blood sera from the first 200 pairs by ELISA. RESULTS The results of the 16S sequencing of vaginal secretions showed that compared with the pregnant group, the non-pregnant group had a significantly increased bacterial species diversity, which was mainly manifested by a decrease in Lactobacillus crispatus and an increase in Prevotella bivia. When Prevotella bivia or Lactobacillus crispatus were mixed with sperms, the sperm motility was decreased (p < 0.05). The vaginal posterior fornix secretions, cervical mucus and peripheral blood sera of the non-pregnant group showed decreased levels of MIP-1α and increased levels of IL-17A (p < 0.05). CONCLUSION The imbalance of vaginal flora leading to the increase of Prevotella bivia and the decrease of Lactobacillus crispatus may cause an imbalance of immune regulation. Low expression of MIP-1α and high expression of IL-17A were associated with reduced clinical pregnancy rate in AIH. This article is protected by copyright. All rights reserved.