Bleeding in pregnancy can be very scary. Here you've been wanting and waiting for this pregnancy and just when you think you've done everything … you're bleeding.

The reasons for bleeding in pregnancy are many and varied. They can be caused by structural problems in the uterus such as a fibroid tumor. This might cause the sloughing off of some of the tissues in the uterus. This is particularly true if it grows or presses on the placenta.

Placenta Previa

Placental issues can occur in many pregnancies. Your placenta may be near or covering the cervix, resulting in what is called “placenta previa.” Your placenta, depending on where it is located in relation to your cervix, can be a marginal previa, where the placenta is near the edge of the cervix; it could be a “partial previa,” where the placenta is partially covering the os, or opening of the cervix. Or if the placenta is completely covering the cervix it's called a “complete placenta previa.”

The earlier the diagnosis is made, the more chance there is that the previa will correct itself. For example, if you were diagnosed with a partial placenta previa at week 18, the chances are good that the placenta would not be covering the cervix at term. As you hit week 20 in your pregnancy, the body of your uterus expands more, allowing the placenta more room to grow away from the cervix. Until that point you may experience periodic bleeding. It may occur after sex, in which case your doctor may put you on pelvic rest — meaning no sexual relations or orgasms. You might also have random bleeding.

Placenta previa can be a life-threatening problem. The mother may bleed to death if she begins to dilate prior to labor or during labor because of the placenta covering the cervix. This causes the baby to die as its oxygen and nutrients are cut off. If this type of placental location is found, the mother will be placed on bed rest, and must avoid sexual intercourse and placing anything in the vagina. The baby will be delivered via cesarean. Though previa is often diagnosed at around twenty weeks gestation, as the second and third trimester continue the body of the uterus grows and the placenta is moved away from the cervix. Only a small percentage of women diagnosed with the placenta previa at twenty weeks will actually have a problem at full term.

There is good news about placenta previa! While it can be a life-threatening problem, it is still possible to give birth to a baby successfully if you suffer from placenta previa. If the placenta is still covering the cervix at or near your due date, your baby will be born via cesarean section. This surgical birth allows the baby to be born without having the cervix dilate. If the cervix were to dilate, the bleeding would increase and it could potentially cause hemorrhaging in you or your baby.

Placenta previa is more common in women who have had prior cesareans. It also occurs more in women who smoke or use drugs.

Subchorionic Bleeding

Another potential problem with the placenta is called subchorionic bleeding. This is a small collection of blood just under the placenta. The blood seeps out from behind the placenta and enters the vagina. Then you notice the bleeding. This can be caused because of the area of implantation, or even trauma that the mother has experienced previously, such as a car accident or a fall.

Whether or not subchorionic bleeding will be problematic depends on the size and the severity of your bleeding. You will be tested by ultrasound, and the results will help your medical team determine your risk for complications in this pregnancy.

There are also times when you might experience bleeding, and doctors can't find a cause or source of the bleeding. In these cases, you will be monitored closely. Remember, if you experience bleeding, do not panic. There may be a good explanation for the bleeding that is not immediately threatening to the pregnancy.