A new study published in the journal *Cell Host & Microbe* suggests that a byproduct from a beneficial bacterium found in the uterus could help preserve fertility as women age. The research, conducted by scientists at Peking University Third Hospital, focused on the uterine microbiome and its role in age-related infertility. While fertility decline is often linked to egg quality, the uterus itself becomes less receptive to embryo implantation over time. The study found that older women had lower levels of beneficial *Lactobacillus* bacteria, particularly *L. gasseri* and *L. crispatus*, in their uterine lining. Among 93 women undergoing IVF, those who became pregnant had higher levels of *Lactobacillus*.