1. The Menstrual Cycle

2. The Menstrual Cycle
The menstrual cycle is a 4-week sequence of events in the female reproductive system. Its purpose is to coordinate the release of an ovum (egg) from one of the ovaries and prepare the uterus to receive a fertilised egg.

3. The Menstrual Cycle
MSNBC menstrual cycle
Hybrid menstrual cycle

4. The Menstrual Cycle Mark on your cycles: The period day 1-5
Ovulation day 14
The fertile period day 14-18
Uterus lining grows day 6-28
Egg matures in ovary day 1-13

5. The Menstrual Cycle Hormones
The menstrual cycle is controlled by the two hormones oestrogen and progesterone.
They are secreted by the ovaries and act on the uterus. They cause the uterus lining to grow thick in preparation for a possible pregnancy.

6. The Menstrual Cycle Hormones
Usually the hormones stop being produced by day 28, so the uterus lining is shed in the period.
If an embryo implants into the uterus lining it starts to secrete progesterone, so the uterus lining remains intact, there is no period and embryo is not lost.
pregnancy