Around ovulation, the pH of the female reproductive tract shifts to favor sperm motility and health.

“and changes to the reproductive pathway, the female in particular, a change in the pH-- that is, the relative acidity versus basic nature of the mucosal lining near the cervix and also vaginal secretions, such that, around the time of ovulation, the entire milieu of the vagina and the cervix and the locations in which fertilization can occur and certainly in which the sperm are swimming towards the opportunity for fertilization is shifted to support sperm motility and health.”