Abstract: A composition and method are disclosed for optimizing sperm survival and function for couples suffering from male infertility by stimulating and increasing the female sexual partner's vaginal lubrication. An increased amount of vaginal transudate is produced in the female by the topical vulval application of a composition containing menthol or a related cooling compound. The resulting increased amount of vaginal transudate can support the function and viability of the spermatozoa in the hostile vaginal environment and ultimately in the cervical mucus to both capacitate sperm in vivo and to provide a medium for gradient sperm differentiation in the vagina and cervix. The inventive composition and method provides a means to compensate for male infertility caused by abnormal semen quality in order for a couple to successfully achieve conception.