Darkening of the vulva during ovulation is a common physiological phenomenon that usually occurs between the 14th and 19th days of a woman's menstrual cycle. During this period, a woman's vaginal discharge will increase, and the vaginal walls and vulva skin will darken, taking on a chocolate-like color.

First, darkening of the vulva during ovulation can help women have a better menstrual cycle. By observing changes in vulva color, women can better understand their hormone levels and thus better respond to physiological changes.

Secondly, the darkening of the vulva during ovulation can promote female reproductive health. The melanin in vaginal secretions protects the vaginal walls and vulvar skin from excessive friction and abrasion. In addition, the nutrients in vaginal secretions can also promote female reproductive health, such as providing necessary moisture and nutrients, preventing infections, etc.

Finally, darkening of the vulva during ovulation is also an important indicator of women's health. By observing changes in the color of the vulva, women can understand their physical condition, such as whether they are suffering from certain diseases.