Miscarriages may occur because of a problem in the fetus (such as a genetic disorder or birth defect) or in the woman (such as a structural abnormality of the reproductive organs, infection, use of cocaine or alcohol, cigarette smoking, or an injury), but the cause is often unknown.
Bleeding and cramping may occur, particularly late in the pregnancy.
Doctors examine the cervix and usually do ultrasonography.
If any remnants of the pregnancy remain in the uterus after a miscarriage, they are removed.
Pregnancy complications are problems that occur only during pregnancy. They may affect the woman, the fetus, or both and may occur at different times during the pregnancy. However, most pregnancy complications can be effectively treated. Miscarriage, by definition, involves death of the fetus, and it may increase the risk of miscarriage in future pregnancies.
A miscarriage occurs in up to 15% of recognized pregnancies. Many more miscarriages are unrecognized because they occur before women know they are pregnant. About 85% of miscarriages occur during the first 12 weeks of pregnancy, and as many as 25% of all pregnancies end in a miscarriage during the first 12 weeks of pregnancy. The remaining 15% of miscarriages occur during weeks 13 to 20.
Causes of Miscarriage
Most miscarriages that occur during the first 10 to 11 weeks of pregnancy are thought to occur because of a genetic disorder. Sometimes miscarriages result from a birth defect.
If women have a disorder that causes blood to clot too easily (such as antiphospholipid antibody syndrome Antiphospholipid Syndrome Autoimmune disorders, including Graves disease, are more common among women, particularly pregnant women. The abnormal antibodies produced in autoimmune disorders can cross the placenta and... read more ), they may have repeated miscarriages (called recurrent pregnancy loss) that occur after 10 weeks of pregnancy.
For many of the miscarriages that occur during weeks 13 to 20, no cause is identified.
Risk factors (conditions that increase the risk of a disorder) for miscarriage include the following:
Older age (over 35)
Structural abnormalities of the reproductive organs, such as fibroids Fibroids A fibroid is a noncancerous tumor composed of muscle and fibrous tissue. It is located in the uterus. Fibroids can cause pain, abnormal vaginal bleeding, constipation, repeated miscarriages... read more , scar tissue, a double uterus, or an weak cervix (cervical insufficiency Cervical Insufficiency Cervical insufficiency is painless opening of the cervix that results in delivery of the baby during the 2nd trimester of pregnancy. Connective tissue disorders that are present at birth and... read more ), which tends to open (dilate) as the uterus enlarges
Use of substances such as cocaine Cocaine during pregnancy More than 50% of pregnant women take prescription or nonprescription (over-the-counter) drugs or use social drugs (such as tobacco and alcohol) or illicit drugs at some time during pregnancy... read more , alcohol Alcohol during pregnancy More than 50% of pregnant women take prescription or nonprescription (over-the-counter) drugs or use social drugs (such as tobacco and alcohol) or illicit drugs at some time during pregnancy... read more , and tobacco Cigarette (tobacco) smoking during pregnancy More than 50% of pregnant women take prescription or nonprescription (over-the-counter) drugs or use social drugs (such as tobacco and alcohol) or illicit drugs at some time during pregnancy... read more (via cigarette smoking)
An underactive thyroid gland (hypothyroidism Hypothyroidism Hypothyroidism is underactivity of the thyroid gland that leads to inadequate production of thyroid hormones and a slowing of vital body functions. Facial expressions become dull, the voice... read more ) or an overactive thyroid (hyperthyroidism Hyperthyroidism Hyperthyroidism is overactivity of the thyroid gland that leads to high levels of thyroid hormones and speeding up of vital body functions. Graves disease is the most common cause of hyperthyroidism... read more ) if either condition is severe or poorly controlled
Certain disorders, such as chronic kidney disease Kidney Disorders During Pregnancy Often, pregnancy does not cause a kidney disorder to worsen. Usually, kidney disorders worsen only in pregnant women who have high blood pressure that is not well-controlled. If pregnant women... read more , systemic lupus erythematosus Systemic Lupus Erythematosus (Lupus) Autoimmune disorders, including Graves disease, are more common among women, particularly pregnant women. The abnormal antibodies produced in autoimmune disorders can cross the placenta and... read more (lupus), and high blood pressure High Blood Pressure During Pregnancy High blood pressure (hypertension) during pregnancy is classified as one of the following: Chronic hypertension: Blood pressure was high before the pregnancy. Gestational hypertension: Blood... read more , if they are not appropriately treated and controlled during pregnancy
Rh incompatibility Rh Incompatibility Rh incompatibility occurs when a pregnant woman has Rh-negative blood and the fetus has Rh-positive blood. Rh incompatibility can result in destruction of the fetus’s red blood cells, sometimes... read more (when a pregnant woman has Rh-negative blood and the fetus has Rh-positive blood) also increases risk of miscarriage.
Sudden emotional shock (for example, resulting from receiving bad news) and minor injuries (for example, resulting from slipping and falling) are not linked with miscarriage.
A miscarriage is more likely if women have had a miscarriage in a previous pregnancy.
The more miscarriages a woman has had, the higher the risk of having another miscarriage. The risk of having another miscarriage also depends on what the cause is, but overall, women who have had several miscarriages have about a 1 in 4 chance of having a miscarriage in a later pregnancy.
Some causes, if not corrected or treated, tend to cause repeated miscarriages. When women have had several miscarriages, the cause may be an abnormality in their or the father's chromosomes or antiphospholipid antibody syndrome.
Symptoms of Miscarriage
A miscarriage is usually preceded by spotting with bright or dark red blood or more obvious bleeding. The uterus contracts, causing cramps. However, about 20% of pregnant women have some bleeding at least once during the first 20 weeks of pregnancy. About half of these episodes result in a miscarriage.
Early in a pregnancy, the only sign of a miscarriage may be a small amount of vaginal bleeding. Later in a pregnancy, a miscarriage may cause profuse bleeding, and the blood may contain mucus or clots. Cramps become more severe until eventually, the uterus contracts enough to expel the fetus and placenta.
Sometimes the fetus dies but no symptoms of miscarriage occur. In such cases, the uterus does not enlarge. Rarely, the dead tissues in the uterus become infected before, during, or after a miscarriage. Such infections (called a septic abortion) usually result from induced abortions done by untrained practitioners who do not use sterile techniques. Septic abortion may be serious, causing fever, chills, bleeding, and a rapid heart rate. Affected women may become delirious, and blood pressure may become dangerously low.
Did You Know...
Diagnosis of Miscarriage
A doctor's evaluation
If a pregnant woman has bleeding and cramping during the first 20 weeks of pregnancy, a doctor examines her to determine whether a miscarriage is likely. The doctor examines the cervix to determine whether it is dilating or pulling back (effacing). If it is not, the pregnancy may be able to continue. If it is dilating before 20 weeks of pregnancy, a miscarriage is highly likely.
Ultrasonography is usually also done. It may be used to determine whether a miscarriage has already occurred or, if not, whether the fetus is still alive. If a miscarriage has occurred, ultrasonography can show whether the fetus and the placenta have been expelled.
Usually, doctors do blood tests to measure a hormone produced by the placenta early in pregnancy called human chorionic gonadotropin (hCG). Results enable doctors to determine whether a woman has a mislocated (ectopic) pregnancy Ectopic Pregnancy Ectopic pregnancy is attachment (implantation) of a fertilized egg in an abnormal location. In an ectopic pregnancy, the fetus cannot survive. When an ectopic pregnancy ruptures, women often... read more , which can also cause bleeding. This test can also help doctors determine whether parts of the fetus or placenta remain in the uterus after a miscarriage.
Doctors can usually diagnose septic abortion based on the woman's circumstances and symptoms. If septic abortion seems likely, doctors send a sample of blood to a laboratory to be cultured (placed in substance that encourages microorganisms to grow). This technique helps doctors identify the microorganism causing the infection and thus determine which antibiotics would be effective.
If women have had several miscarriages, they may want to see a doctor before they try to become pregnant again. The doctor can check them for genetic or structural abnormalities and for other disorders that increase the risk of a miscarriage. For example, doctors may do the following:
An imaging test (such as ultrasonography, hysteroscopy, or hysterosalpingography) to look for structural abnormalities
Blood tests to check for certain disorders, such as antiphospholipid antibody syndrome, diabetes, hormone abnormalities, and thyroid disorders
Genetic tests to check for chromosomal abnormalities
If identified, some causes of a previous miscarriage can be treated, making a successful pregnancy possible.
Treatment of Miscarriage
For threatened abortion, periodic evaluation of the woman's symptoms
For complete abortion, no treatment
For other types of abortion, removal of the contents of the uterus
If the fetus is alive and the cervix has not opened (threatened abortion), no specific treatment can help, but doctors periodically evaluate the woman's symptoms or do ultrasonography.
Some doctors advise women to avoid strenuous activity and, if possible, to stay off their feet. However, there is no clear evidence that such limitations are helpful. There is also no evidence that refraining from sexual intercourse helps.
If a miscarriage has occurred and the fetus and the placenta have been completely expelled, no treatment is needed.
If some tissue from the fetus or placenta remains in the uterus after a miscarriage or if the fetus dies and remains in the uterus, doctors may do one of the following:
If women have no fever and do not appear ill, closely monitor them while waiting to see whether the uterus will expel its contents on its own. Whether this approach is safe depends on how much tissue is left, how the uterus appears on an ultrasound of the pelvis, and when the miscarriage is thought to have occurred.
Surgically remove the fetus and placenta through the vagina (called surgical evacuation Surgical abortion Induced abortion is the intentional ending of a pregnancy by surgery or drugs. A pregnancy may be ended by surgically removing the contents of the uterus or by taking certain drugs. Complications... read more , using suction curettage or dilation and evacuation [D & E]), usually during the first 23 weeks of pregnancy
Use a drug that can induce labor and thus expel the contents of the uterus, such as oxytocin (usually used later in the pregnancy) or misoprostol (usually used earlier in the pregnancy)
Before surgically removing the fetus during the 1st or 2nd trimester, doctors may use natural substances that absorb fluids (such as seaweed stems) to help open the cervix. Or they may give the woman a prostaglandin (a hormonelike drug that stimulates the uterus to contract), such as misoprostol. These treatments make removal of the tissues easier.
If a drug is used, suction curettage or D & E may be needed afterward to remove pieces of the placenta. D & E may not be available because it requires special training.
If women have symptoms of a septic abortion, the contents of the uterus are removed as soon as possible, and women are treated with antibiotics, given intravenously.
Emotions after miscarriage
After a miscarriage, women may feel grief, sadness, anger, guilt, or anxiety about subsequent pregnancies.
Grief: Grief for a loss is a natural response and should not be suppressed or denied. Talking about their feelings with another person may help women deal with their feelings and gain perspective.
Guilt: Women may think that they did something to cause the miscarriage. Usually, they have not. Women may recall taking a common over-the-counter drug early in pregnancy, drinking a glass of wine before they knew they were pregnant, or doing another everyday thing. These things are almost never the cause of a miscarriage, so women should not feel guilty about them.
Anxiety: Women who have had a miscarriage may wish to talk with their doctor about the likelihood of a miscarriage in subsequent pregnancies and be tested if needed. Although having a miscarriage increases the risk of having another one, most of these women can become pregnant again and carry a healthy baby to term.
Doctors offer their support and, when appropriate, reassure women that the miscarriage was not their fault. Formal counseling is rarely needed, but doctors make it available for women who want it.