Menstruation and pregnancy are two completely incompatible with each other event. Who is pregnant does not menstruate, and who is menstruating cannot be pregnant. However, it is important to clarify by stating that pregnant women may not menstruate is not the same as saying that pregnant women may not have frequent episodes of vaginal bleeding during pregnancy. The point is that these bleeding can have many causes but of course, that menstruation never is one of them.
If you have any suspicion that the above statement is not correct and not just think that a pregnant woman can menstruate, but is also able to cite individual cases where this situation occurred, I suggest you read this text carefully as he will take your questions. So you can understand the reason for the total incompatibility between pregnancy and menstruation, we must first explain what menstruation is and how it happens.
The outermost layer of the wall of the uterus is called the endometrial. In each menstrual cycle, the endometrial prepares to receive a possible embryo. This process takes place through the proliferation of endometrial cells and the development of blood vessels, which are responsible for fluid and nutrient supply to the fetus future. The preparation of the uterus for bleeding during pregnancy happens all month and begins on the first day of the menstrual cycle first being stimulated by the hormone estrogen and progesterone hormone.
If we do an ultrasound in the early days of the menstrual cycle we will see a thin endometrial with a single layer less than 0.4 cm thick and poor in blood vessels. As the days pass, the hormonal stimulation causes the endometrial cells to proliferate and form new blood vessels. In the final phase of the cycle, the endometrial becomes thick, with 3 layers, viscous, rich in blood vessels and about 1.5 cm thick which is almost 4 times thicker than at the beginning of the cycle.
After ovulation, if the egg is not fertilized within about 24 hours, it degenerates and ends the stimulus for the production of estrogen and progesterone. As there is no longer any possibility of bleeding during pregnancy in this cycle, there is no reason the agency prepare the uterus for implantation of an embryo. Without the presence of the hormones estrogen and progesterone the thick wall of the endometrial loses its stimulus to proliferate and the blood supply is suddenly interrupted. As a result, the wall of the endometrium starts to collapse, taking with her endometrial, mucus, water and blood tissue.
- Produce a growing estrogen to induce ovulation and endometrial proliferation rate.
- Ovulate and will not be fertilized, since the absence of fertilization of the ovum and degeneration is caused to hormonal stimulation, which, in turn, leads to the collapse of the uterine wall.
When a woman uses birth control pills, uses hormones to trick the reproductive system, causing the endometrium to proliferate, but without inducing ovulation. When the pill is stopped, the endometrium collapses and menstruating patient. When the egg is fertilized, instead of estrogen and progesterone levels drop quickly, as occurs when the fertilized egg does not degenerate, they do the opposite rising keeping the endometrium thick and ready to receive the embryo. This is the first point: if the woman he would tarry menstruating after fertilization, the endometrium and flaked would not be able to receive or maintain viable embryo that has just arrived.