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INTRODUCTION — A miscarriage is a failed intrauterine pregnancy that ends before 20 weeks from the last menstrual period. A brief review of the events of early pregnancy will help in the understanding of miscarriage.
A female's reproductive system includes the uterus (including the cervix), two ovaries, two fallopian tubes, and the vagina. The fallopian tubes are a pair of hollowed tubes that run from each side of the uterus to the ovaries (figure 1). Once a month, an egg is released by one of the ovaries and travels down the fallopian tube. If the egg is fertilized in the tube by the male's sperm, pregnancy begins.
Once the egg and sperm join, they rapidly develop new cells. This bundle of cells, called the embryo, normally implants on the inner wall of the uterus. Once implanted, the embryo continues to grow inside a sac of amniotic fluid, sometimes called the "bag of water." After several weeks, the embryo is called a fetus.
MISCARRIAGE RATES — Miscarriage in early pregnancy is common. Studies show that approximately 8 to 20 percent of persons who know they are pregnant have a miscarriage some time before 20 weeks of pregnancy; 80 percent of these occur in the first 12 weeks [1]. But the actual rate of miscarriage is even higher since many people have very early miscarriages without ever realizing that they are pregnant. One study that followed hormone levels every day to detect very early pregnancy found a total miscarriage rate of 31 percent [2].
MISCARRIAGE CAUSES — Many factors can lead to miscarriage, and it is difficult to say with certainty what causes a particular miscarriage to occur. One or more problems with the pregnancy can be found in a significant percentage of early miscarriages.
As an example, in one-third of miscarriages occurring before 8 weeks, there is a pregnancy sac but no embryo inside. This means the egg was fertilized and the cells began to divide, but an embryo did not develop. In other cases, the embryo develops but it is abnormal. Chromosomal abnormalities, in particular, are common. One study found that of more than 8000 miscarriages, 41 percent had chromosomal abnormalities.
In some cases, medical conditions in the mother, such as uncontrolled diabetes, or structural problems in the reproductive tract, such as uterine fibroids, can lead to miscarriage. (See "Patient education: Care during pregnancy for patients with type 1 or 2 diabetes (Beyond the Basics)" and "Patient education: Uterine fibroids (Beyond the Basics)".)
Some studies have suggested that taking nonsteroidal antiinflammatory drugs (NSAIDs) very early in pregnancy may increase the risk of miscarriage; however, there are conflicting data about this and evidence is limited. It is reasonable to avoid NSAIDs if you are trying to get pregnant. NSAIDs include ibuprofen (sample brand names: Advil, Motrin) and naproxen (sample brand name: Aleve).
MISCARRIAGE RISK FACTORS — Several risk factors can increase the rate of miscarriage.
●Age – Older individuals are more likely to have a miscarriage than younger persons.
●Previous miscarriage – Having a miscarriage in the past may increase the risk for a future miscarriage.
●Smoking – Smoking more than 10 cigarettes a day increases the risk of miscarriage.
●Alcohol – No amount of alcohol is known to be safe during pregnancy because it can cause health problems for the baby. Drinking alcohol also increases the risk of miscarriage.
●Fever – Pregnant people who develop fevers of 100°F (37.8°C) or more appear to have an increased risk of miscarriage.
●Trauma – Trauma to the uterus can increase the risk of miscarriage. This includes some forms of prenatal testing, such as amniocentesis or chorionic villus sampling. The effect of minor trauma to the mother’s abdomen is unknown, because during early pregnancy the uterus is generally protected from blunt trauma. (See "Patient education: Amniocentesis (Beyond the Basics)" and "Patient education: Chorionic villus sampling (Beyond the Basics)".)
●Other causes – People who are exposed to certain substances or conditions may have an increased risk of congenital abnormalities and miscarriage. This includes exposure to certain infections, medications, radiation, physical stresses, and environmental chemicals.
It does not appear that caffeine intake increases the risk of miscarriage, with the possible exception of intake of very high levels (ie, 1000 mg, or 10 cups of coffee, over 8 to 10 hours).
MISCARRIAGE SIGNS AND SYMPTOMS — The most common signs of miscarriage are vaginal bleeding and abdominal pain early in pregnancy. These problems should always be evaluated by a clinician. However, bleeding and discomfort can occur in normal pregnancies. In many cases, bleeding resolves on its own and the pregnancy continues normally without further problems.
MISCARRIAGE DIAGNOSIS — In some cases, miscarriage can be diagnosed based upon the person's symptoms and the physical examination. As an example, a patient who presents with an open cervix that contains pregnancy tissue can be diagnosed with a miscarriage.
However, in many cases of vaginal bleeding in early pregnancy, ultrasound is used to establish a diagnosis, and/or to help determine if the pregnancy is "viable," that is, whether it is capable of progressing to term. In addition, it is important to make sure that the pregnancy is in the uterus. Pregnancies outside the uterus (eg, in the fallopian tube) need immediate evaluation and care and can be life threatening. (See "Patient education: Ectopic (tubal) pregnancy (Beyond the Basics)".)
Ultrasound — Ultrasound uses sound waves to visualize the structures inside the uterus. In early pregnancy, the ultrasound exam is often done through the vagina. Ultrasound findings that diagnose a non-viable pregnancy include no pregnancy sac, a pregnancy sac of certain size without an embryo, or an embryo without a heartbeat.
If an embryo is present, its size is measured and compared with the size that is expected at the patient's stage of pregnancy. The sac and other materials surrounding the embryo are also examined to look for abnormalities in these structures.
Fetal heartbeat — At approximately 6 weeks after the last menstrual period, the motion of the fetal heart should be visible on ultrasound. If the pregnancy has progressed to the stage where a heartbeat should be present, the failure to detect a heartbeat during an ultrasound exam indicates that the pregnancy has likely ended.
On the other hand, the presence of a fetal heart beat (in the absence of other abnormalities in the pregnancy) indicates the pregnancy may still be viable and that miscarriage may not occur.
Doctors will also evaluate the rate of the fetal heart. A fetal heart beat that is less than 100 to 120 beats per minute can indicate that a miscarriage is likely.
MISCARRIAGE TREATMENT OPTIONS — Unfortunately, there is no way to stop most miscarriages once they have started. When a miscarriage is inevitable or is already occurring, several options are available, depending upon the stage of the miscarriage, the condition of the mother, and other factors. The three main options are: observation, medical treatment, or surgical treatment.
Observation — Some people having a miscarriage require little treatment. Most individuals with complete miscarriage fall into this group. In addition, those who miscarry at less than 12 weeks of pregnancy and have stable vital signs (blood pressure, pulse) and no signs of infection can often be managed without medical or surgical treatment.
In time, the contents of the uterus will pass, usually within two weeks, although sometimes as long as 3 to 4 weeks later. Once the contents have been passed, an ultrasound is done to ensure that the miscarriage is complete.
Medical treatment — In some cases, medications can be given to stimulate the uterus to pass the pregnancy tissue. The medicine can be given by mouth or vaginally, and works over several days.
Surgical treatment — The conventional treatment for early miscarriage is a surgical procedure called dilation and curettage, or D&C. The cervix (the opening to the uterus) is dilated, and an instrument is inserted that uses suction and/or a gentle scraping motion to remove the contents of the uterus. (See "Patient education: Dilation and curettage (D&C) (Beyond the Basics)".)
D&C is generally recommended for people who do not want to wait for spontaneous passage of the pregnancy, and in people with heavy bleeding or infection.
AFTER MISCARRIAGE — Following miscarriage, patients are advised to avoid having sex or putting anything into the vagina, such as a douche or tampon, for two weeks. Patients have traditionally been told to wait two to three months before trying to become pregnant again, although several studies have shown no increased risks with a shorter interval. Any type of birth control, including an intrauterine device, may be started immediately. (See "Patient education: Birth control; which method is right for me? (Beyond the Basics)".)
Medications may be given to help decrease bleeding and reduce the risk of infection. In addition, those who have an Rh negative blood type (ie, A, B, AB, or O negative) may need to be given a drug called Rh(D) immune globulin (RhoGam). This medicine helps protect future fetuses against problems that can occur if an Rh negative mother is carrying a baby who is Rh positive.
Emotional health — People experience a range of emotions following miscarriage; there is no right or wrong way to feel. The loss of a pregnancy can cause significant grief. Sometimes these reactions are strong and long-lasting. You should let your health care provider know if you are feeling profound sadness or depression following pregnancy loss, especially if it continues for greater than several weeks. Referral for grief counseling or other treatment may be helpful. (See "Patient education: Depression in adults (Beyond the Basics)".)
WHERE TO GET MORE INFORMATION — Your health care provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient education: Pregnancy loss (The Basics)
Patient education: Coping after pregnancy loss (The Basics)
Patient education: Dilation and curettage (D&C) (The Basics)
Patient education: Bleeding in early pregnancy (The Basics)
Patient education: Repeat pregnancy loss (The Basics)
Patient education: Hyperthyroidism (overactive thyroid) and pregnancy (The Basics)
Patient education: Pregnancy in Rh-negative people (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient education: Care during pregnancy for patients with type 1 or 2 diabetes (Beyond the Basics)
Patient education: Uterine fibroids (Beyond the Basics)
Patient education: Amniocentesis (Beyond the Basics)
Patient education: Chorionic villus sampling (Beyond the Basics)
Patient education: Dilation and curettage (D&C) (Beyond the Basics)
Patient education: Birth control; which method is right for me? (Beyond the Basics)
Patient education: Depression in adults (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Recurrent pregnancy loss: Definition and etiology
Effects of advanced maternal age on pregnancy
Recurrent pregnancy loss: Evaluation
Recurrent pregnancy loss: Management
Pregnancy loss (miscarriage): Clinical presentations, diagnosis, and initial evaluation
Pregnancy loss (miscarriage): Terminology, risk factors, and etiology
Antiphospholipid syndrome: Obstetric implications and management in pregnancy
The following organizations also provide reliable health information.
●National Library of Medicine
(www.nlm.nih.gov/medlineplus/pregnancyloss.html, available in Spanish)
●The March of Dimes
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