Impact of Vaginal Microbiome on Vaginal Absorption of Exogenous Progesterone: a Pilot Study.

Is already demonstrated that around 30% of patients undergoing an artificial cycle with vaginal progesterone do not reach a minimum threshold value of serum progesterone levels on the day of embryo transfer. Women with serum progesterone levels below this threshold have 20% lower ongoing pregnancy and live birth rates, decreasing their chances of success. However, the cause of this high heterogeneity in exogenous vaginal progesterone absorption among our patients remains unknown. It has been suggested that vaginal microbiome, and vaginal pH (due to its impact in microbiota growth), may explain the differences in vaginal progesterone absorption. The aim of the present pilot study is to assess if certain vaginal conditions, such as its microbiome status or its pH level, might affect vaginal progesterone absorption (measured by serum progesterone levels) and, in turn, the chances of success. In order to evaluate it, a prospective cohort unicentric study will be conducted in IVI RMA Valencia (Spain). Infertile patients undergoing an embryo transfer in the context of an artificial cycle when using vaginal progesterone will be recruited. Serum progesterone and estradiol levels, microbiome genetic analysis in vaginal samples and vaginal pH will be measured both on the embryo transfer-scheduling day and on the embryo transfer day.