The short answer is: they’re connected, but not the same — and research is still evolving.
The uterine microbiome refers to the microbial community found throughout the uterus, while the endometrial microbiome specifically refers to the microbes in the endometrium — the inner lining of the uterus that plays a key role in implantation and pregnancy. Because the uterus is a low-biomass environment (meaning it contains very few microbes), studying it is challenging and prone to contamination. That’s why our understanding of these microbiomes is still limited.
That said, some overlap has been observed between the vaginal and uterine (or endometrial) microbiomes. And since the vagina acts as the “gatekeeper” to the upper reproductive tract, many researchers believe that supporting vaginal health may also benefit the uterine environment.
Importantly, nearly all interventions for vaginal or uterine health are delivered vaginally — so it makes practical sense to start by testing and treating the vaginal microbiome. It’s currently the most accessible and actionable way to support the full reproductive ecosystem.
In short: while we can’t easily test the uterine or endometrial microbiome yet, supporting your vaginal microbiome is a powerful place to start.