adjective
menstrual
MEN-stroo-ul/ˈmenstruəl/
Relating to the body's cycle of bleeding from the uterus.
During menstrual bleeding, the uterine lining sheds and leaves the body.

Etymology
The base means “monthly,” and the resulting Latin adjective could refer especially to the monthly courses. That specialized use underlies the English connection with uterine bleeding.
In context
the first phase of the uterine cycle is the menstrual phase and this is cycle days one through six this is when the woman will have bleeding
More examples
- A heating pad helps ease her menstrual cramps.
- She tracks her menstrual cycle on a calendar.
- Heavy menstrual bleeding can lead to iron deficiency.
Forms
menstrual
menstruation noun — Periodic shedding of the uterine lining with bleeding.