because the egg is not needed so the lining of the stomach is not needed to protect the egg. The lining breaks down and this is a period.
When you get your period it is uterus blood. Your period is the uterus shedding its lining if you do not get pregnant. All month your uterus builds up its lining for if your egg gets fertilized, and when/if it does not get fertilized, you have your period at the end of the month.
That happens every month when you menstruate or if you've had an abortion and it comes back every month. And yes, you can because the sperm fertilize the egg in the fallopian tube, not the uterus.
The inside of the uterus is lined with the "endometrium" which is shed every month if you are not pregnant. Once you get pregnant that lining changes to the "decidua" which stays in place because of the hormone progesterone and hCG the pregnancy hormone during pregnancy.
endometrium
If you are referring to menstruation, they do not bleed from their 'butts'. The blood is the thickened lining of the uterus detaching and falling out. This happens once every month if the woman does not become pregnant as the Uterus lining grows to give a resting place for a fertilised egg to become a foetus and then a baby. If the egg is not fertilised by sperm following sex, the lining of the Uterus is not needed and is rejected by the body.
true
Period blood comes from the shedding of the uterine lining, which builds up each month in preparation for a potential pregnancy. If pregnancy does not occur, the lining is no longer needed and is expelled from the body through the vagina during menstruation.
During the menstrual cycle, the uterus prepares for a possible pregnancy by building up its lining (endometrium). If fertilization does not occur, the uterus sheds this lining during menstruation. The hormones involved in the menstrual cycle regulate these changes in the uterus.
The uterus lining, or endometrium, thickens in preparation for a potential pregnancy each month. If fertilization does not occur, hormonal changes lead to a decrease in estrogen and progesterone levels, which causes the endometrium to break down and shed. This shedding results in menstruation, during which the lining becomes thinner as it is expelled from the body. In the absence of pregnancy, the thinning of the lining is a natural part of the menstrual cycle.
A plasenta is a uterus!
The uterus lining will come loose and a mentral cycle will begin.
That would be called, the woman's period