It is not possible to menstruate during pregnancy, but there are a few things that can cause a woman to bleed during pregnancy. Implantation bleeding, decidual bleeding, and miscarriage are all things that can make a woman think she is menstruating during pregnancy when in fact she is not. Most types of bleeding that occur during pregnancy, with the exception of miscarriage, are usually not a major concern and may not be a threat to the health of the mother or fetus. Any menstrual bleeding that occurs during pregnancy should be reported immediately to a doctor so that the possibility of miscarriage can be confirmed or ruled out.
The reason it is not possible for a woman to menstruate during pregnancy is because the body releases hormones that cause the menstrual period to stop. When a woman has her period, her uterine lining thickens and flakes off. During pregnancy, this lining protects and helps nourish the fetus instead of thickening and coming out like a period. A small amount of bleeding during the first trimester is quite common and can occasionally be perceived as a period when it is not. This often results in many women not realizing their pregnancy until two or three months have passed.
Implantation bleeding, while usually mild, is often perceived as a period during pregnancy. This bleeding is usually one of the first signs to alert a woman to the fact that she is pregnant, but as it usually occurs at the time when a woman expects her period to arrive, it is often mistaken for a menstrual period. Implantation bleeding is usually best described as spotting, and is usually light pink or brown in color. This bleeding usually occurs about a week after conception and is a result of the embryo implanting in the uterine wall. Implantation bleeding is normal and not dangerous in any way, but it can cause a woman to miscalculate her due date if she thinks it’s a period.
Decidual bleeding is another type of bleeding that often occurs during early pregnancy. This type of bleeding is usually the result of parts of the uterine lining shedding before it is fully attached to the placenta. Not all women have decidual bleeding, but it’s almost always in the first trimester when it occurs. A woman with decidual bleeding should visit her doctor, but in most cases it is not a cause for concern.
Miscarriage is another cause of bleeding during pregnancy. If a woman does not know that she is pregnant, she may believe that a miscarriage is actually her period at the start. A woman who knows about her pregnancy will likely worry that something is wrong, because a miscarriage often causes painful cramping along with heavy bleeding. When a miscarriage occurs, it is most common during the first three months of pregnancy, although it can also occur later. A woman who thinks she may be having a miscarriage should seek medical attention immediately.