Infertility: vaginal bacteria and viruses both implicated

Infertility, a sensitive subject that affects more than 15% of couples of reproductive age, might (also) have its source in our vaginal microbiota!

This idea, already discussed in relation to in vitro fertilization (IVF) or infertility in general, is reinforced by a study ¹ conducted on 136 Mexican women diagnosed with primary infertility (no pregnancy after 12 months of trying) or secondary infertility (difficulty becoming pregnant again after a first pregnancy).

The researchers scrutinized vaginal samples from these women to better understand what is really happening in their microbiota, and the connection with fertility.

Higher age, fewer lactobacilli

First of all, age is revealed to be a crucial factor. The older a woman is, the higher her risk of primary infertility, while secondary infertility seems to affect younger women more. However, it has long been known that the vaginal microbiota evolves with age. Beneficial vaginal bacteria (the well-known Lactobacillus) progressively lose their hegemony and give way to less favorable bacteria. For the researchers, these changes could partially explain why it becomes more difficult to get pregnant naturally (or with medical assistance) when the decades start to add up.

Two types of infertility, two different types of microbiota

But above all, the researchers showed that the women suffering from primary infertility and those diagnosed with secondary infertility presented with different vaginal microbiota.

• Among women suffering from primary infertility, the beneficial Lactobacillus species, although still in the majority, had lost their dominance in favor of bacteria that our vaginas could do without, such as the duo Gardnerella vaginalis and Fannyhessea vagina, implicated in vaginosis (sidenote: Bacterial vaginosis Bacterial vaginosis (BV) is a type of vaginal inflammation caused by an imbalance of the bacterial species that are normally present in the vagina. ) . But that’s not all: the presence of G. vaginalis seems to be strongly associated with human papillomavirus (HPV) infection. Some serious bad actors!
• Among women suffering from secondary infertility, their flora is also disturbed, but in a different way: G. vaginalis often goes hand in hand with the herpes virus; bacteria responsible for sexually transmitted infections (STIs) are also present.

Hence the importance, for the authors, of having not only pathogenic bacteria in our sights, but also viruses, since they seem to work in concert, with a cumulative impact on infertility. There is still hope, however: the vaginal microbiota should help us better understand infertility and come up with personalized treatments.