What is menstruation?

Menstruation is the process of the shedding of the uterine lining on a regular monthly basis in women. During menstruation, the uterus wall along with blood vessels break off. This causes blood to come out and a new wall of the uterus is formed. Menstruation generally lasts for 4 to 5 days.Phases of the menstrual cycleThe menstrual cycle is divided into four phases, namely:1. Menstrual phase: Day 1, uterus lining which is prepared for implantation starts to shed which lasts 3 to 5 days.2. Follicular phase: A matured egg follicle releases an egg from one of the ovaries. Also, the uterus starts preparation for another pregnancy.3. Ovulatory phase: Mid-cycle phase, is the phase in which ovulation takes place i.e., day 13-17. The end of the follicular phase along with the ovulation period defines the fertilization period.4. Luteal phase: Post ovulation phase where the fate of corpus luteum is decided. If fertilization occurs, pregnancy starts. If fertilization doesn't occur, it marks the onset of another cycle.