Sexually transmitted infections in women are associated with an increased risk of death and the development of other diseases, including urethritis, pelvic inflammatory disease, amniotic fluid infection, and the risk of preterm birth in pregnancy. Pelvic inflammatory disease involves infection and inflammation of the upper parts of the female reproductive system – the endometrium, fallopian tubes and ovaries, which can lead to infertility, ectopic pregnancy and chronic pelvic pain. The vaginal microflora consists of different types of bacteria that are in balance with each other. The most widespread are lactobacilli, which maintain an acidic environment in the vagina, protecting it from infections. A change in the balance of the vaginal microflora is called bacterial vaginosis. It has been established that the most common infections that lead to infertility in women are infections with Ureaplasma urealyticum, Mycoplasma hominis, Chlamydia trachomatis and human papilloma virus – HPV. Also, infections with Chlamydia trachomatis, Neisseria gonotthoeae and Ureaplasma urealyticum have a confirmed negative effect on fertility. Of all these agents, chlamydia is associated with the highest risk of developing pelvic inflammatory disease, which is characterized by pelvic pain and the risk of infertility and ectopic pregnancy. One of the frequent reasons for the lack of success in assisted reproduction are disorders in the structure and functions of the fallopian tubes, as well as the presence of Mycoplasma in the vagina. Bacterial vaginosis, which is caused by an imbalance of bacteria in the vagina, is a leading cause of infertility. In cases where the infection is caused by various pathogens, the balance in the vaginal flora is disturbed, which leads to the involvement of the cervix and predisposes to infertility. Co-infection with Mycoplasma and Chlamydia trachomatis has the greatest influence in this direction. Also, a reduced population of Lactobacillus bacteria is associated with reduced chances of getting pregnant. Bacterial vaginosis is a condition that leads to a significant reduction of those bacterial populations that, under normal conditions, have a protective effect on the vagina. Various studies have shown that infections with more than two types of pathogens are associated with an increased risk of infertility, as well as a decreased possibility of fertilization even through assisted reproduction. Mycoplasma infection has been found to lead to increased production of pro-inflammatory cytokines, which contribute to increased inflammatory processes and development of complications in assisted reproduction or post-implantation embryo growth. References: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6439431/