Menstrual Effluent and Fecundity

The endometrium is crucial for successful embryo implantation and subsequent maintenance of the pregnancy. Until recently, assessment of endometrial receptivity has relied on invasive techniques such as endometrial biopsy. However, recent studies have shown that menstrual effluent exhibits similar properties to tissue obtained from an endometrial biopsy. The objective of this project is to examine whether alterations in endometrial receptivity affect fertility and risk of miscarriage by quantifying and analyzing menstrual effluent. We hypothesize that low menstrual volume, luteal phase bleeding, and alterations in the distribution of immune cells and cytokines in menstrual effluent will be associated with a decrease in the probability of conceiving in a given menstrual cycle (fecundability) and an increase in the risk of miscarriage. The proposed study will enroll 695 women from the community who desire to conceive, and measure, collect, and analyze their menstrual effluent. Participants will be actively followed throughout their attempts to conceive over the following twelve months. During that time, women will conduct standardized ovulation and pregnancy testing and complete a daily diary that captures bleeding patterns. Pregnancy follow-up will include ultrasound assessment for viability and a pregnancy outcome report. These methods will allow us to address our primary research aims: 1) Determine the extent to which endometrial proliferation and luteinization impact fecundity. To address this aim, we will determine the association between menstrual volume and bleeding patterns with a) fecundability and b) miscarriage. 2) Determine the extent to which the uterine immune microenvironment impacts fecundity. To address this aim, we will determine the association between mononuclear cells and cytokines in the menstrual effluent and a) fecundability and b) miscarriage. Our study is innovative in its use of menstrual effluent as a measure of uterine receptivity. Identifying non-invasive methods to assess endometrial receptivity and the uterine microenvironment could lead to new diagnostics and treatments for infertility and recurrent pregnancy loss. Project Number: 1R01HD119059-01A1 | Fiscal Year: 2026 | NIH Institute/Center: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) | Principal Investigator: Anne Steiner | Institution: UNIV OF NORTH CAROLINA CHAPEL HILL, CHAPEL HILL, NC | Award Amount: $586,356 | Activity Code: R01 | Study Section: Integrative and Clinical Endocrinology and Reproduction Study Section[ICER] View on NIH RePORTER: https://reporter.nih.gov/project-details/11359528