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Miscarriage is the spontaneous loss of pregnancy during the first 20 weeks of gestation. It is also called "spontaneous abortion," or early pregnancy loss.
Miscarriage is very common. As many as 30% of women will experience one, usually before they even miss a period, or realize they are pregnant. Most early miscarriages are a result of a developing fetus that is unhealthy and has no chance of surviving to the end of pregnancy.
Some known causes of miscarriage include:
- Chromosomal abnormalities. Studies show that 50% to 60% of all miscarriages are caused by chromosomal abnormalities in the fetus. Of these cases about half are caused by the presence of an extra chromosome, such as Trisomy 21, also called Down Syndrome.
- Uterine abnormalities. Structural defects in the cavity of the uterus that interfere with the blood supply to the uterus can also cause miscarriage. These defects include some types of fibroid, uterine septums, scarring and possibly large polyps.
- Infections and diseases. Some bacterial and viral infections can contribute to a miscarriage, particularly in the second trimester. These include viral infections, such as the cytomegalovirus, bacterial infections such as streptococcus, or in rare cases parasitic infection such as toxoplasmosis. Disease, such as undiagnosed diabetes, may also cause a miscarriage.
- Age of the mother. The rate of miscarriage increases with the age of the mother. Around half of all pregnancies in women over 40 end in miscarriage. This is largely due to the increasing rate of chromosomal abnormalities seen in the eggs of older women.
- Autoimmune diseases. Regulation problems in the immune system is thought to contribute to miscarriages, though there is limited evidence supporting this hypothesis. The presence of certain complex antibodies, such as the lupus anticoagulant and the anticardiolipin antibodies, is several fold higher in women who have miscarriages, though this may be due to an effect on clotting. No randomized, controlled studies have demonstrated that treatments aimed at modifying the immune system to prevent miscarriage have any beneficial effect. These factors are not well understood, and there is no agreed upon effective treatment.
- Blood clotting. Thrombophilia, or the propensity to clot, is a more common cause of miscarriage in the second trimister. The use of blood thinners, such as low molecular weight heparin and aspirin may be of benefit. But they should be used only with caution and under the care of an experienced clinician.
- Other possible causes. Chronic illnesses, exposure to environmental toxins (such as certain metals), and stress. Examples include thyroid problems (either overactive or underactive thyroid), poorly controlled diabetes, or intrauterine adhesions (most commonly caused by previous infections or procedures such as dilation and curettage). High dose radiation and chemotherapy are known toxins that can cause pregnancy loss. Industry employees working with chemicals, such as dyes, metals or solvents, are at greater risk. Maternal stresses and heavy use of tobacco, caffeine, alcohol, and drugs can also be factors.
Women often blame themselves for having a miscarriage. It is important to remember that, in the vast majority of cases, there was something fundamentally wrong with the way the fetus formed, and nothing the mother did could have changed that. And keep in mind that having one miscarriage does not necessarily mean having another. The chances are very high that you'll carry your next baby to full term.
How Do I Know If I'm Having A Miscarriage?
If you are pregnant and have any of these symptoms, call your health care provider immediately:
- Vaginal bleeding. Especially heavy bleeding with passage of blood clots.
- Abdominal pain. Severe or persistent pain in the pelvis or lower back.
- Blood clots. If you do pass tissue at home your health care provider will likely instruct you to collect the tissue and place it in a clean jar or plastic bag to bring in for medical inspection.
- The early ending of morning sickness symptoms and loss of breast tenderness. Many women experience these symptoms in the first trimester, but by the beginning of the fourth month of pregnancy, they commonly subside. When women experience a loss of these symptoms earlier than the second trimester, and if symptoms subside abruptly, miscarriage may have occurred.
Your health care provider will listen for a fetal heartbeat and perform a pelvic exam. If a heartbeat is not heard or your cervix is dilated, or widened, or if your membranes have ruptured, then most likely a miscarriage is in progress, or has already happened. This may be termed an "inevitable miscarriage." If a fetal heartbeat is detected and your cervix is still closed, you may have suffered a "threatened miscarriage." In this case, you will have vaginal bleeding but the fetus is still alive. In a threatened miscarriage, bleeding may resolve, and the pregnancy can go on to a normal full-term delivery. However, any time there is bleeding in pregnancy, be sure to check with your doctor to see if you need to take medicine called Rhogam. Depending on your blood type, an injection of this medicine may be necessary to prevent you from developing antibodies against blood cells in future pregnancies.
An ultrasound and physical exam can be helpful in sorting out what’s happening. An ultrasound test emits high-frequency sound waves that penetrate the uterus to reveal an image of the fetus on a monitor. If no image of the fetus is seen or if you can see fetal tissue traveling through the dilated cervix, then you may have had a miscarriage, or are in the process of one. If the fetus looks intact and your uterus is still enlarged, then you may have suffered a threatened miscarriage. Some women do not have any symptoms after the miscarriage. This is known as a missed abortion. When this happens, the miscarriage may go undetected for several weeks, until the next prenatal visit. If a fetal heartbeat is not heard after eight to 10 weeks gestation and there is no sign of uterine growth, then a miscarriage probably took place.
Many miscarriages happen before a woman knows she's pregnant. Miscarriages can be mistaken for periods that are unusually heavy and severe. Bleeding early in pregnancy before an intrauterine pregnancy has been confirmed may be a sign of an ectopic pregnancy. If you have any concerns about your last period, talk to your health care provider.
How Is It Treated?
Options for treatment include:
- D & E (dilation and evacuation). During the surgery, the cervix is dilated or widened and both a suction curette and a sharp curette are used to empty the remaining tissue from the lining of the uterus.
- Vacuum aspiration. A mechanical pump is used to suction the remaining tissue out of the uterus.
- Medical management. The woman is given a medication that causes uterine contractions. Most women will pass the pregnancy within 24 hours of taking the medication. If miscarriage does not occur, the woman undergoes a surgical treatment (D and C or vacuum aspiration).
Bleeding may continue for several weeks after a miscarriage and change in color from bright red to pink or brown. You may also experience abdominal cramping.
If the bleeding gets heavier after a few weeks instead of decreasing, contact your health care provider. If a fever develops, or if vaginal discharge has a strange or unpleasant odor, inform your doctor. Avoid intercourse, douching, or using tampons for at least two weeks and then gradually resume normal activities, such as exercise.
How Can I Prevent It?
It most cases, nothing can be done to prevent a miscarriage. If you know you are pregnant, make sure you get proper prenatal care and talk to your health care provider about diet prenatal vitamins. Most of the time, however, miscarriages happen because the embryo didn’t form correctly. The miscarriage is actually your body’s way of naturally passing the pregnancy to give you a chance for a future, healthy, pregnancy
After a threatened miscarriage, take it easy for a few days, and avoid intercourse for a few weeks. Most likely you will carry your baby to term. Remember, it's very normal for women to bleed in early pregnancy, and it's certainly not always an indication that the fetus is unhealthy or that you are having a miscarriage. In fact, some women bleed throughout their pregnancy. It should be brought to your health care provider's attention as bleeding can be associated with other medical problems such as uterine fibroids, abnormal placental implantation, chronic abruptio (relatively rare). Talk to your health care provider about any concerns you have.
Frequently Asked Questions
Q: I've already had one miscarriage. Does this mean I'm more likely to have another one?
A: Having one miscarriage does not increase your chances of having another. If you have had only one prior miscarriage, the rate of spontaneous abortion in a subsequent pregnancy is similar to the overall rate in the general population.
Q: After my miscarriage, how long should I wait before I try to conceive again?
A: It is usually suggested that you wait two normal periods (around eight weeks) before you try to conceive again. That’s largely to let you recover emotionally from losing a pregnancy. If you do conceive before you’ve had two normal periods, you’re not at higher risk of having problems with your next pregnancy. If you do want to wait for a few cycles, be aware that ovulation can resume as early as two weeks after a miscarriage, so you should use effective contraception immediately.
Q: Can being too active cause a miscarriage?
A: No. Working, exercise, and sexual activity do not increase the risk of miscarriage.
Q: I have had two miscarriages. Should I have special testing?
A: Since most miscarriages are caused by a defect of the particular fertilized egg, most experts do not recommend special testing until you have had three miscarriages. At that point it is termed "recurrent" or "habitual" miscarriage and further testing may be needed. Studies have shown that after a woman experienced three consecutive miscarriages, her chance of having subsequent spontaneous abortion is nearly 50%.
- Last reviewed on 12/9/2012
- Irina Burd, MD, PhD, Maternal Fetal Medicine, Johns Hopkins University, Baltimore, MD. Review provided by VeriMed Healthcare Network.
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This page was last updated: April 14, 2014