Emerging research suggests that changes in sexual functioning after concussion/mild traumatic brain injury (mTBI) are common in women of reproductive age (18-45years). Findings from my pilot research show that 61.3% of women who sustain a concussion report sexual dysfunctions (SD)-defined as disordered sexual interest, desire, arousal or satisfaction-compared to 40% of extremity injured controls of similar menstrual and birth control status. Although concussion symptoms typically resolve within weeks, this line of research demonstrates that for a subgroup of patients, symptoms can linger into months if not years, and can adversely affect an important, yet understudied, aspect of women’s health and function. Human sexuality, according to the World Health Organization (WHO), is an essential aspect of health, a central aspect of “being human.” Poor sexual functioning assumes pathology in the experience of sexual arousal, interest, desire and response, and it has been associated with adverse physical and mental health. It is a marker of quality of life (QOL). In order to decrease the public health burden of mTBI and improve the clinical care of women with concussion, research is needed to identify women at greatest risk for post- concussion SD. Understanding sex-difference in TBI outcomes and the unique challenges faced by women with TBI is a priority for the Neurology’s National Institute of Neurological Disorders and Stroke (NINDS). This K01 application proposes a research plan that incorporates hormonal biomarkers as a novel risk stratification tool to identify high risk groups of female concussion patients. Study participants will use the Ovia® digital reproductive health tracking application (app) and other validated questionnaires to document their sexual activities and relevant covariates. In Aim 1 we test the hypothesis that compared to women with extremity injuries, concussed women will a) have a lower mean score on the BIQS measure of sexual function and b) have fewer sexual encounters reported with Ovia app, evaluated at 1& 3-months post-injury. In Aim 2 we test if women with mTBI injured during the luteal menstrual phase will have a higher risk of SD than women with mTBI injured during the follicular menstrual phase (lower mean score on BIQS and fewer sexual encounters with app); and if the magnitude of the association will be significantly higher for women with mTBI than for women with extremity injuries. I will receive mentoring, career advising and training to develop an independent research program that bridges my epidemiologic skillset with my interests in neurology and reproductive epidemiology.