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 about 10 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 chromosome disorder Overview of Chromosome and Gene Disorders Chromosomes are structures within cells that contain a person's genes. A gene is a segment of deoxyribonucleic acid ( DNA) and contains the code for a specific protein that functions in one... read more . Sometimes miscarriages result from a birth defect Overview of Birth Defects Birth defects, also called congenital anomalies, are physical abnormalities that occur before a baby is born. They are usually obvious within the first year of life. The cause of many birth... read more .
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 consecutive miscarriages (called recurrent pregnancy loss Recurrent Miscarriage Recurrent (repeated) miscarriages is having had at least 2 miscarriages. Recurrent miscarriages may be caused by problems in the mother, father, fetus, or placenta. Chromosome abnormalities... read more ) that occur before 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:
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 a 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 and 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
Infections during pregnancy, Infections During Pregnancy Most common infections that occur during pregnancy, such as those of the skin, urinary tract, and respiratory tract, cause no serious problems. However, some infections can be passed to the... read more such as a cytomegalovirus infection Cytomegalovirus (CMV) Infection Cytomegalovirus infection is a common herpesvirus infection with a wide range of symptoms: from no symptoms to fever and fatigue (resembling infectious mononucleosis) to severe symptoms involving... read more or rubella Rubella Rubella is a contagious viral infection that typically causes mild symptoms, such as joint pain and a rash, but can cause severe birth defects if the mother becomes infected with rubella during... read more
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 Hemolytic Disease of the Fetus and Newborn 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.
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 to 30% 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. If any fragments of the fetus or placenta remain in the uterus, infection may develop.
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. Infection of the uterus that occurs during or shortly before or after a miscarriage or an abortion is called a septic abortion Septic Abortion Septic abortion is a serious infection of the uterus that occurs shortly before, during, or shortly after an abortion or a miscarriage. Septic abortions usually develop when untrained practitioners... read more .
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. A pelvic examination Pelvic Examination For gynecologic care, a woman should choose a health care practitioner with whom she can comfortably discuss sensitive topics, such as sex, birth control, pregnancy, and problems related to... read more is done. 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 completely 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, such as the fallopian tubes. In an ectopic pregnancy, the fetus cannot survive. When an ectopic pregnancy... read more , which can also cause bleeding. This test can also help doctors determine whether the fetus is alive, whether a miscarriage has occurred, and, if so, whether parts of the fetus or placenta remain in the uterus after the miscarriage.
If the uterus does not progressively enlarge or if hCG levels do not increase as expected during pregnancy, doctors suspect a missed abortion. That is, the fetus has died but has not been expelled from the uterus.
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 chromosome abnormalities
If identified, some causes of a previous miscarriage can be treated, making a successful pregnancy possible.
Treatment of Miscarriage
For complete abortion, no treatment
For threatened abortion, periodic evaluation of the woman's symptoms (observation)
For inevitable, incomplete, or missed abortions, observation or removal of the contents of the uterus
Rho(D) immune globulin if the mother has Rh-negative blood
Sometimes pain relievers
If a miscarriage has occurred and the fetus and the placenta have been completely expelled, no treatment is needed.
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 activity helps.
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, doctors 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.
Before 12 weeks of pregnancy, women can wait until the pregnancy passes by itself, or doctors can prescribe a medication that can expel the contents of the uterus (misoprostol, sometimes with mifepristone). Or doctors can remove the contents of the uterus by dilation and curettage (D and C) with suction Surgical abortion applied through a flexible tube inserted through the vagina into the uterus.
At 12 to 23 weeks, doctors surgically remove the contents of the uterus 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 dilation and evacuation [D & E]).
Between 16 and 23 weeks, a drug that can induce labor and thus expel the contents of the uterus may be used. These drugs include oxytocin (usually used later in the pregnancy) and 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 hormone-like 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.
Pain relievers are given as needed.
All women who have Rh-negative blood and have had a miscarriage are given Rho(D) immune globulin Prevention 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 to prevent hemolytic disease of the fetus Hemolytic Disease of the Newborn Hemolytic disease of the newborn is a condition in which red blood cells are broken down or destroyed by the mother's antibodies. Hemolysis is the breakdown of red blood cells. This disorder... read more (erythroblastosis fetalis). This disorder is caused by Rh incompatibility Hemolytic Disease of the Fetus and Newborn 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).
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. Support groups may be helpful.