Review of the evidence of the effects of human papillomavirus infection and Gardnerella vaginalis, and their co-infection on infertility.

A prevalent sexually transmitted infection, the human papillomavirus (HPV) is typically obtained just after the first sexual activity. The majority of HPV infections are asymptomatic and temporary. Cervical, anal, penile, vaginal, vulvar, and oropharyngeal cancers can occur due to recurrent infections with high-risk (hr)-HPV strains, generally decades later. Infections with HPV are significantly associated with reproductive function abnormalities. Per recent research, HPV infections may result in male infertility by reducing sperm motility. The hr-HPV infection was a risk factor for miscarriage, and the indiscriminate HPV genotype increased the probability of premature labor unexpectedly. Women's endometrial trophoblastic cell implantation is decreased by HPV. Gardnerella vaginalis (GV), an anaerobic bacterium that is a component of the natural vaginal flora, can be associated with bacterial vaginosis (BV) when it starts to overgrow and emerge as the dominant species. Reduced Lactobacillus species abundance and GV are linked to female infertility. Data from in vitro studies suggests that sialidase produced by GV may facilitate the entry and growth of papilloma and other sexually transmitted viruses. Also, based on some studies conducted in the past, it can be said that GV and BV are associated with the development of uterine cancer. However, there is still not enough information about the exact mechanism of GV and HPV in causing infertility, which requires more research.