Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Vaginal bleeding in the first trimester of pregnancy can be caused by several different factors. Bleeding affects 20% to 30% of all pregnancies. Up to 50% of those who bleed may go on to have a miscarriage (lose the
baby). Of even more concern, however, is that about 3% of all pregnancies are
ectopic in location (the fetus is not inside the uterus), and vaginal bleeding
can be a sign of an ectopic pregnancy. An ectopic pregnancy may be life threatening to the mother. All bleeding associated with early pregnancy should prompt a call to your health care provider for immediate evaluation.
Implantation bleeding: There can be a small amount of
spotting associated with the normal implantation of the embryo into the
uterine wall, called implantation bleeding. This is usually very minimal, but
frequently occurs on or about the same day as your period was due. This can be
very confusing if you mistake it for simply a mild period and don't realize
you are pregnant. This is a normal part of pregnancy and no cause for concern.
Threatened miscarriage: You may be told you have a
threatened miscarriage if you are having some bleeding or cramping. The fetus is definitely still inside the uterus (based usually on an exam using ultrasound), but the
outcome of your pregnancy is still in question. This may occur if you have an
infection, such as a urinary tract infection,
become dehydrated, use
certain drugs or medications, have been involved in
physical trauma, if the developing fetus is abnormal in some way, or for no apparent reason at all. Other than these reasons, threatened miscarriages are generally not caused by things you do, such as heavy lifting or having sex, or by
Completed miscarriage: You may have a completed miscarriage (also called a spontaneous abortion) if your bleeding and cramping have slowed down and the uterus appears to be empty based on ultrasound evaluation. This means you have lost the pregnancy. The causes of this are the same as those for a threatened miscarriage. This is the most common cause of first trimester bleeding.
Incomplete miscarriage: You may have an incomplete miscarriage (or a miscarriage in progress) if the pelvic exam shows
your cervix is open and you are still passing blood, clots, or tissue. The cervix should not remain open for very long. If it does, it indicates the miscarriage is not completed. This may occur if the uterus begins to clamp down before all the tissue has passed, or if there is infection.
Blighted ovum: You
may have a blighted ovum (also called embryonic failure). An ultrasound would
show evidence of an intrauterine pregnancy, but the embryo has failed to develop as it should in the proper location. This may occur if the fetus were abnormal in some way and not generally due to anything you did or didn't do.
Intrauterine fetal demise: You may have an intrauterine fetal demise (also called IUFD, missed abortion, or
embryonic demise) if the developing baby dies inside the uterus. This
diagnosis would be based on ultrasound results and can occur at any time
during pregnancy. This may occur for any of the same reasons a threatened
miscarriage occurs during the early stages of pregnancy; however it is very uncommon
for this to occur during the second and third trimesters of pregnancy. If it
does, the causes also include separation of the placenta from the uterine wall
(called placental abruption) or because the placenta didn't receive sufficient blood flow.
Ectopic pregnancy: You may have an ectopic pregnancy (also called tubal pregnancy).
This would be based on your medical history and ultrasound, and in some cases
laboratory results. Bleeding from an ectopic pregnancy is the most dangerous
cause of first trimester bleeding. An ectopic pregnancy occurs when the
fertilized egg implants outside of the uterus, most often in the Fallopian
tube. As the fertilized egg grows, it can rupture the Fallopian tube and cause
life-threatening bleeding. Symptoms are often variable and may include pain, bleeding, or lightheadedness. Most ectopic pregnancies will cause pain before the tenth week of pregnancy. The fetus is not going to develop and will die because of lack of supply of nutrients. This condition occurs in about 3% of all pregnancies.
There are risk factors for ectopic pregnancy. These include a history of prior ectopic pregnancy, history of pelvic inflammatory disease, history of
Fallopian tube surgery or ligation, history of infertility for more than 2 years, having an
IUD (birth control device placed in the uterus) in place,
smoking, or frequent (daily) douching. Only about 50% of women who have an ectopic pregnancy have any risk factors, however.
Molar pregnancy: You may have a molar pregnancy (technically called gestational trophoblastic disease). Your ultrasound results may show the
presence of abnormal tissue inside the uterus rather than a developing fetus. This is actually a type of
tumor that occurs as a result of the hormones of pregnancy, and is usually not life-threatening to you. However, in rare cases the abnormal tissue is cancerous.
If it is cancerous it can invade the uterine wall and spread throughout the body. The cause of this is generally unknown.
Postcoital bleeding is vaginal bleeding after sexual intercourse. It may be normal during pregnancy.
Bleeding may also be caused by reasons unrelated to pregnancy. For example, trauma or tears to the vaginal wall may bleed, and some infections may cause bleeding.