Reproductive Microbiomes

To date, diet and lifestyle choices have received a lot of attention in relation to rising infertility rates, but now emerging research confirms we should also factor in both the seminal and vaginal microbiomes.

Yes, fertility – or infertility – just got a little more complicated. Which of course is exactly why we research, to uncover yet another piece of a puzzle.

Microbiome research has previously focussed on species inhabiting our gut, skin and oral cavity, and scientists thought that the seminal/vaginal terrain was a relatively sterile environment, meaning that the presence of bacteria indicated pathology. Now, advances in molecular techniques have enabled researchers to identify ‘commensal’ bacteria – (i.e. friendly, supportive species, living symbiotically with us) – that fulfil a defensive role protecting us against pathogenic species.

So it raises the question: does the presence of any specific microbiotic species correlate with fertility status?

Answer: Yes. Research has shown samples of sperm with normal morphology, in fertile men, have predominantly a Lactobacillus species microbiome, whereas sperm samples with abnormal morphology taken from infertile men have shown a predominance of Pseudomonas and Prevotella species.

Similarly with the vaginal microbiome, healthy fertile women have predominantly Lactobacillus species dominating, ensuring an acidic pH that favours both the motility and viability of sperm.

Bacterial vaginosis is characterized by depletion of Lactobacillus species, augmented with a diversity of anaerobic bacteria. This condition affects 20–50% of reproductive-age women and is now seen as a risk factor for subfertility and infertility. The consensus now is that IVF outcomes and assisted reproductive techniques could be improved with screening patients’ microbiomes. A prospective study of reproductive-age women undergoing IVF found that embryo implantation was less successful in women with reduced Lactobacillus species in their vaginal microbiota.

Previously it was believed the upper reproductive tract was sterile, but we now know the endometrium of the uterus also has a microbiome, and again – a predominance of Lactobacillus species (>90%) supports better implantation rates, whereas a more diverse microbiota inhibiting and producing a lower proportion of Lactobacilli can be the cause of implantation failure.

There are of course other factors affecting fertility and further studies are required to determine the role of the seminovaginal microbiome in fertility success, because the presence of Lactobacilli varies with confounding variables in the form of different ethnicities, geographies and socioeconomic status, making it potentially more complicated to establish what an optimal ‘healthy’ seminovaginal microbiome should consist of.

However with such promising research, functional testing is following hot on the heels and is already available through Invivo Laboratory, offering a ground-breaking clinical tool, for accurate analysis of microbiota abundance, pH and host inflammatory markers. Opportunistic/pathogenic fungi and bacterial species can be identified along with the abundance – or otherwise – of the lactobacillus species we want to see.

Through a simple swab, their ‘Female EcologiX Vaginal Health and Microbiome Profile’ can enable women to assess vaginal health status, and if indicated, their ‘Bio.Me Femme V’ oral Lactobacillus probiotic has been shown in a human clinical trial to positively influence and crucially colonise the vaginal terrain.

If you and your partner are interested in investigating reproductive health or optimising fertility, book in for an online consultation. Tests can be carried out in the privacy of your own home.



  1. The semen microbiome and its impact on sperm function and male fertility: A systematic review and meta-analysis
  2. Microbiota and Human Reproduction: The Case of Female Infertility
  3. Application of Ligilactobacillus salivarius CECT5713 to Achieve Term Pregnancies in Women with Repetitive Abortion or Infertility of Unknown Origin
  4. Moreno I & Simin C (2018) Relevance of assessing the uterine microbiota in infertility. Fertil Steril. 110: 337-343

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