A miscarriage is the loss of a pregnancy before 20 weeks, the point at which a fetus might be able to survive outside the womb. Miscarriage also is called spontaneous abortion or natural abortion. In a miscarriage, the woman's body expels all or some of the fetus, the placenta and the fluid surrounding the baby.

About 15% to 20% of known pregnancies end in a miscarriage, and many more happen before a woman recognizes she is pregnant. Most miscarriages happen before 16 weeks. In many cases, the fetus died days or weeks before the symptoms of miscarriage began. In the first several weeks of pregnancy, a miscarriage sometimes happens because an embryo did not properly form into a fetus, a situation known as a blighted ovum.

Miscarriage most often happens when the fetus has abnormal chromosomes, the pieces of DNA that contain genes and determine what we are like. Chromosome problems account for approximately 50% of all miscarriages. About 95% of the time, the parents' chromosomes are normal and the genetic abnormality has developed as a one-time error in the fetus. In such cases, miscarriage is the body's way of ending a pregnancy that is not developing normally.

Miscarriages also can happen if there are problems with the internal structure of a woman's uterus or the strength of her cervix. For example, some women are born with a uterus that has a thick membrane (septum) extending through its middle. This can nearly or completely divide the womb into two chambers, and a uterus with this shape may not hold a pregnancy securely. A woman's cervix, which should open during labor and delivery to allow the fetus to pass through, is sometimes too weak to keep the fetus safe inside the womb until delivery. When the cervix is too weak and opens early in pregnancy, it is called an incompetent cervix. Problems with the structure of the uterus and an incompetent cervix are the two most common causes of miscarriage during the first part of the second trimester (12 to 20 weeks).

Other causes of miscarriage include infections and hormonal imbalances. In rare cases, a woman's immune system rejects the fetus, or antibodies from the immune system cause problems with blood flow in the placenta. Immune-system disorders are responsible for miscarriages in 5% to 10% of women who have had 3 or more miscarriages in a row. One fairly common antibody problem that can lead to miscarriage is called antiphospholipid antibody syndrome.

Women with diseases such as poorly controlled diabetes or severe hypothyroidism (underactive thyroid) are at higher risk of miscarriage. Having rubella (German measles) during early pregnancy has been associated with miscarriage. Environmental factors, such as smoking cigarettes and drinking alcoholic beverages during pregnancy, may increase your risk of having a miscarriage. Miscarriage is not caused by regular physical activities, minor accidents, exercise, sexual intercourse, or minor stumbles or falls.

Miscarriages and possible miscarriages are categorized in several ways:

• Threatened miscarriage. A miscarriage is considered threatened, or possible, when any bleeding from the uterus occurs before 20 weeks, but the cervix is closed and the fetus is alive.



• Inevitable abortion or miscarriage. A miscarriage is called inevitable, meaning it cannot be stopped, if there is bleeding from the uterus and the cervix is opening prior to 20 weeks, but neither the fetus nor placenta have passed out of the woman's body. The membranes around the fetus may or may not have ruptured (broken).



• Incomplete abortion or miscarriage. A miscarriage is incomplete when a portion of the fetus or placenta has passed out of the uterus prior to 20 weeks gestation, but some of the placenta or fetus remains in the uterus.



• Complete miscarriage. A miscarriage is complete if the fetus, all the membranes around the fetus and the placenta are expelled completely and the cervix closes prior to 20 weeks.



• Missed abortion or miscarriage. A missed abortion refers to a miscarriage in which the fetus has died prior to 20 weeks gestation, but neither the fetus nor the placenta has been expelled from the uterus.



• Recurrent miscarriage. A woman is said to have recurrent miscarriage after three or more miscarriages in a row. Approximately 1% of women experience recurrent miscarriages.



• Blighted ovum or anembryonic gestation. This occurs when a gestational sac forms inside the uterus, but no fetus is present after seven weeks.

If a pregnancy ends after 20 weeks, it is not considered a miscarriage. It is a delivery. If the fetus is not living, it is called a stillbirth.

Symptoms of miscarriage include:

• Vaginal bleeding that may start as a brownish discharge
• Cramps in the pelvic area, lower back or abdomen
• A decrease in the usual signs of early pregnancy, such as nausea and breast tenderness
• Pain in the lower back or abdomen
• Tissue or blood clots passing from the vagina

If miscarriage is suspected or has occurred, your doctor will do a pelvic examination to check the size of your uterus and determine whether your cervix is open or closed. If a miscarriage is in progress, the cervix is usually open and the pregnancy will not survive. If a miscarriage has already happened, the cervix can be either open or closed, depending on whether all the pregnancy tissue has passed out of the womb.

Blood tests usually are done to verify your blood type and check the level of human chorionic gonadotropin (beta-hCG), a hormone released by the placenta into your body when you are pregnant. If the amount of the pregnancy hormone in your system is low or if repeated tests show the level has decreased over time, it is a sign you may have had a miscarriage. An ultrasound is done in almost every case to identify if a fetus is present, if the fetal heart is beating, or if there is evidence a fetus has died.

If pregnancy tissue has passed out of your vagina, you can bring it to your doctor in a glass jar or plastic container with a tightly sealed lid. It may be helpful for your doctor to inspect this tissue, although this is not necessary to diagnose a miscarriage. In some cases, this tissue can be sent to a laboratory to be examined under a microscope. This may help to determine the reason for the miscarriage, or it may help to determine whether the miscarriage is complete.

First-trimester miscarriages may require you to stay home and rest for a few days while you have what seems like a heavy period. The bleeding and crampy pain will gradually decrease over one to two weeks. Miscarriages that happen in the second trimester may be followed by a longer period of bleeding.

If a miscarriage is about to occur, usually you can't prevent it. However, you may be able to decrease your chances of having a miscarriage in a future pregnancy by taking good care of yourself, eating a healthy diet, taking folic acid supplements, exercising regularly, and avoiding alcohol or smoking.

If you have had several miscarriages in a row, your doctor may recommend that you and your partner undergo genetic testing, tests such as ultrasound, a camera inspection of the inside of the uterus or specialized X-ray examinations to determine the form and shape of the uterine cavity and cervix, and possibly a blood test to evaluate your immune system. These tests can help to identify why you keep having miscarriages.

If miscarriage is threatened in the first or early second trimester, your doctor may suggest that you rest in bed, avoid strenuous exercise and abstain from sexual intercourse for a period of time. These measures have not been proven to help prevent miscarriage, but many health care professionals suspect they may help sometimes.

If your pregnancy is in danger because of an incompetent cervix, a suture or stitch (called a cerclage) may be placed around the cervix to tighten it and keep the cervical canal closed. If a cerclage is used, it usually is removed by cutting the stitch after 36 or more weeks of pregnancy. While the cerclage is in place, you will be monitored very closely.

If you have a missed or incomplete miscarriage, your obstetrician/gynecologist (OB/GYN) may perform a surgery called dilation and curettage (D and C) to stretch open your cervix gently and remove any remaining fetal tissue from your uterus. If you are in your late second trimester of pregnancy, your doctor most likely will admit you to a hospital and induce labor so that you can deliver the fetus and placenta safely.

If a miscarriage occurs because of a problem with the internal structure of your uterus, you may be able to have surgery to correct the problem before getting pregnant again.

Call the health care professional who is monitoring your pregnancy immediately if you have symptoms of a miscarriage, such as vaginal bleeding, severe pain, a foul-smelling vaginal discharge, or if you develop a fever.

Your chances of having another miscarriage depend on the cause of the miscarriage. About 90% of women who have had 1 miscarriage have a healthy pregnancy the next time. However, if you keep having miscarriages, it's possible you have a problem that needs to be addressed, such as an abnormal uterus, a genetic abnormality or an immune system reaction. The general recommendation for attempting pregnancy after a miscarriage is to wait about two to three months before trying to conceive again.

American College of Obstetricians and Gynecologists
P.O. Box 96920
Washington, DC 20090-6920
Phone: 202-638-5577
http://www.acog.org/

American College of Nurse Midwives
8403 Colesville Road
Suite 1550
Silver Springs, MD 20910
Phone: 240-485-1800
Fax: 240-485-1818
http://www.midwife.org/

National Institute of Child Health and Human Development
Building 31, Room 2A32
MSC 2425
31 Center Drive
Bethesda, MD 20892-2425
Toll-Free: 1-800-370-2943
TTY: 1-888-320-6942
Fax: 1-866-760-5947
Email: nichdinformationresourcecenter@mail.nih.gov
http://www.nichd.nih.gov/

National Institute of Diabetes and Digestive and Kidney Disorders
Office of Communications and Public Liaison
Building 31, Room 9A04
31 Center Drive, MSC 2560
Bethesda, MD 20892-2560
Phone: 301-496-3583
Email: niddk_inquiries@nih.gov
http://www.niddk.nih.gov/