Impact of genital microbiota on fertility

Around 1 in 5 couples in France experiences fertility problems. In 75% of cases, an aetiology is found: female, male or mixed causes with a significant proportion of infectious aetiologies. Until recently, the focus has largely been on pathogenic bacteria.

However, in recent years, the study of host-microbiota interactions has led to the discovery of mechanisms directly involving dysbioses in infertility. In particular, the notion of the existence of a continuum between the vaginal microbiota and the cervical and endometrial microbiota has provided a better understanding of the vaginal microbiota’s influence on the female upper genital tract. While it was recognised that vaginal dysbiosis favours colonisation of the upper genital tract with pathogenic bacteria, it is now shown that it also promotes the rise of commensal bacteria with a harmful effect on the endometrial mucosa.

The end of the microbiologically sterile sperm dogma has also changed our view of male fertility. While the composition of "normal" seminal microbiota remains controversial, we know that its alteration changes sperm quality and that once it reaches the vagina, the sperm’s quality can also be disrupted by the action of the vaginal microbiota.

These discoveries shed new light on the causes of infertility and implantation failures with medically-assisted reproduction protocols. The search for female and male genital dysbioses appears to be an increasingly useful exploration for understanding the mechanisms of human infertility, with the prospect of new therapeutic pathways likely to be key.

I hope you enjoy reading this issue.

Jean-Marc Bohbot,
Editor in Chief of this issue