Vaginal mucus is a natural substance occurring within the vagina, particularly the cervix, that maintains a certain level of moisture at all times. The volume, colour, and consistency of vaginal mucus changes according to the period of the menstrual cycle. Both the chemical make-up and the physical consistency (viscosity) change during this time. A slippery, clear, egg white-like consistency usually indicates that the woman is ovulating. Relative dryness usually indicates an infertile point in the menstrual cycle.