Why does bleeding occur during pregnancy?

There are several different reasons why a woman may have vaginal bleeding during pregnancy. Some women continue to have light periods or spotting during pregnancy, mainly during the first few months. A pregnancy test could probably help to ease your mind. A visit to your doctor may also be in order, either for early pregnancy care or for finding out the reasons for these symptoms.

Possible causes for bleeding:

Early Pregnancy and Implantation Bleeding

It's estimated that about 25% of all women have bleeding in early pregnancy. One possible cause of such bleeding is implantation bleeding.

Implantation bleeding is lighter as compared to menstrual bleeding, and consists of either pink or brown colored blood. It occurs when the trophoblast, or the tissue that surrounds the egg, gets attached to the endometrium and slowly finds its way into the lining. As it does so, it eats through the mother's blood vessels, forming blood lakes within itself. When these blood lakes form near the surface of the trophoblast, they often cause implantation bleeding.

The difference between period and implantation bleeding is the quantity; implantation bleeding is significantly lighter than menstrual bleeding. Implantation bleeding and menses should be different enough so that you can tell. The duration of implantation bleeding is different for different women.

Miscarriage

Bleeding while pregnant doesn't indicate that miscarriage is certain, but it is possible. About half of the women who bleed during pregnancy do not have miscarriages. Miscarriage may occur at any time during the first half of pregnancy. Most miscarriages occur during the first 12 weeks. Miscarriage occurs in nearly 15 to 20 percent of pregnancies. Most miscarriages cannot be prevented. They are often the body's way of dealing with a pregnancy that is not normal. There is no relevant proof that exercise or sex causes miscarriage.

Ectopic Pregnancy

Another problem that could cause pain and bleeding in early pregnancy is ectopic pregnancy. If pregnancy occurs in fallopian tube, it may burst. Ectopic pregnancies are much less common as compared to miscarriages. They occur in about one in 60 pregnancies.

Molar Pregnancy

A rare cause of early bleeding could be molar pregnancy. It is also known as gestational trophoblastic disease (GTD) or a "mole." It is the growth of abnormal tissue in place of an embryo.

Late Pregnancy

The causes of bleeding during the second half of pregnancy differ from those in early pregnancy. Common conditions that lead to minor bleeding include an inflamed cervix or growths on the cervix.

Placental Abruption

The placenta can detach from the uterine wall before or during labor. This causes vaginal bleeding. Only 1 percent of pregnant women experience placental abruption. It generally occurs during the last 12 weeks of pregnancy. Stomach pain frequently occurs, even if there is no obvious bleeding.

Placenta Previa

When the placenta lies low in the uterus, it may partly or wholly cover the cervix. This is called placenta previa. This can cause vaginal bleeding. Placenta previa is very serious and requires prompt care.

Labor

In late pregnancy, vaginal bleeding could be a sign of labor. A plug which covers the opening of uterus during pregnancy is passed just before or at the start of labor. A small quantity of mucus and blood is passed from the cervix. This is called "bloody show." It is very common. It is not a problem if it happens within a few weeks of the due date.