Reacción a "A study involving mice and humans suggests that a bacterial supplement could improve female fertility"

The press release reflects the study’s findings fairly accurately and also includes an important word of caution, noting that these results do not justify the use of commercial Lactobacillus gasseri supplements to improve fertility. The study provides interesting evidence that reproductive ageing is associated with changes in the endometrial microbiome and explores a possible biological mechanism through which certain postbiotics might influence endometrial receptivity.

This is a study of high methodological quality, published in a high-impact journal, which combines data from a patient cohort with mechanistic experiments in cell cultures and animal models, thereby lending biological rigour to the hypotheses put forward. However, it is important to note that most of the functional evidence comes from preclinical models and that the human study is observational; consequently, it cannot establish a causal relationship between the decline in L. gasseri and reduced fertility. The authors themselves acknowledge significant limitations, such as the small size of the clinical cohort, the fact that it was drawn from a single centre, the complexity of studying the endometrial microbiome due to the low bacterial content of these samples, and the possible influence of hormonal factors associated with reproductive ageing.

Overall, this study adds to the growing evidence that the microbiome of the female reproductive tract may play a role in endometrial function, although we are still a long way from translating these findings into clinical practice. Before considering therapeutic strategies based on probiotics or postbiotics, it will be necessary to confirm these findings in multicentre studies and, above all, in randomised clinical trials that demonstrate a real benefit on clinically relevant outcomes, such as implantation rates, ongoing pregnancy and live births. At present, these results should be interpreted as a promising line of research rather than as an intervention ready to be incorporated into patient care.