On average how long is the human menstrual cycle?

On average, the human menstrual cycle lasts for around 28 days. However, it is important to note that this can vary significantly from woman to woman, with some women experiencing cycles that are shorter or longer than 28 days.

A typical menstrual cycle consists of four phases:

1. The follicular phase begins on the first day of menstruation and ends when ovulation occurs. During this phase, the ovaries produce estrogen, which helps to thicken the lining of the uterus in preparation for implantation of a fertilized egg.

2. Ovulation occurs when a mature egg is released from one of the ovaries. This usually happens 14 days before the start of the next period.

3. The luteal phase begins after ovulation and ends when menstruation begins. During this phase, the corpus luteum (a small gland that forms on the ovary after ovulation) produces progesterone, which helps to maintain the lining of the uterus. If the egg is not fertilized, the corpus luteum will disintegrate and the levels of progesterone and estrogen will drop, leading to the shedding of the uterine lining and the onset of menstruation.

4. Menstruation is the shedding of the lining of the uterus through the vagina. This usually lasts for 3-7 days.