THE MENSTRUAL CIRCLE

This is the various changes that occurs in the uterus and ovary for the purpose of sexual reproduction. The menstrual circle is essential for the production of eggs and for the preparation of the uterus for pregnancy.It only occurs in fertile female humans and other female primates.
The length of a menstrual circle varies among women ranging from 21 to 35 days with 28 days being the average.
The menstrual circle can be divided into 3 phases. A circle is counted from the first day of one period to the first day of the next period. The way and manner the hormones rise and falls during the month controls the menstrual circle.
In the first phase of the menstrual circle, the level of the female hormone called the estrogen rises. Estrogen also makes the lining of the womb grow and thicken.
The second  stage is called the ovulation. This is when an egg is released from the ovary into the fallopian tubes.  A woman can get pregnant at this time  if sperm fertilizes the egg. A woman with a 28 days circle will ovulate on the  fourteenth day of her circle
The last phase  is the phase after ovulation. Hormones are further released  to thicken the lining of the uterus in preparation for a fertilized egg. If  a woman becomes pregnant, the fertilized egg attaches itself to the lining of the uterus, but if she doesn't get pregnant,  the lining is shed off and this comes out as  the menstruation and another circle begins.