Recurrent miscarriages may be caused by problems in the mother, father, fetus, or placenta.
Chromosome abnormalities may cause about half of recurrent miscarriages.
Causes of Recurrent Miscarriage
The problem causing repeated miscarriages may be in the mother, father, fetus, or placenta.
In the mother, common problems that cause repeated miscarriages include
Abnormalities in the uterus or cervix, such as polyps Cervical Polyps Cervical polyps are common fingerlike growths of tissue that protrude into the passageway through the cervix. Polyps are almost always benign (noncancerous). Cervical polyps may be caused by... read more
, bands of scar tissue (adhesions Causes ), and 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 
Poorly controlled chronic disorders, such as 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
), 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 
), diabetes Diabetes Mellitus (DM) Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Urination and thirst are... read more , high blood pressure High Blood Pressure High blood pressure (hypertension) is persistently high pressure in the arteries. Often no cause for high blood pressure can be identified, but sometimes it occurs as a result of an underlying... read more 
, and chronic kidney disease Chronic Kidney Disease Chronic kidney disease is a slowly progressive (months to years) decline in the kidneys’ ability to filter metabolic waste products from the blood. Major causes are diabetes and high blood pressure... read more
If women have a disorder that causes blood to clot too easily (such as antiphospholipid 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 that occur after 10 weeks of pregnancy, The reason may be blood clots that damage the placenta and thus decrease the flow of nutrients from the mother to the fetus.
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.
Chromosome disorders in the father may also cause repeated miscarriages. Having certain abnormalities in semen increases the risk of miscarriage. Whether older age (over 35) of the father increases risk of a miscarriage is unclear.
In the fetus, common causes include
Chromosome or genetic abnormalities
Structural abnormalities (birth defects)
Chromosome abnormalities 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 in the fetus may cause 50% of repeated miscarriages. Miscarriages due to chromosome abnormalities are more common during early pregnancy.
Problems with the placenta include chronic disorders that are poorly controlled, such as systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more 
(lupus) and chronic high blood pressure High Blood Pressure High blood pressure (hypertension) is persistently high pressure in the arteries. Often no cause for high blood pressure can be identified, but sometimes it occurs as a result of an underlying... read more .
The cause of repeated miscarriages cannot be determined in up to half of women.
Diagnosis of Recurrent Miscarriage
A doctor's evaluation
Tests to identify the cause
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:
Genetic tests to check for chromosomal abnormalities in both parents
An imaging test (such as ultrasonography Ultrasonography Sometimes doctors recommend screening tests, which are tests that are done to look for disorders in people who have no symptoms. If women have symptoms related to the reproductive system (gynecologic... read more
, sonohysterography Hysteroscopy Sometimes doctors recommend screening tests, which are tests that are done to look for disorders in people who have no symptoms. If women have symptoms related to the reproductive system (gynecologic... read more , or hysterosalpingography Hysterosalpingography Sometimes doctors recommend screening tests, which are tests that are done to look for disorders in people who have no symptoms. If women have symptoms related to the reproductive system (gynecologic... read more ) to look for structural abnormalitiesBlood tests to check for certain disorders, such as antiphospholipid syndrome, diabetes, hormone abnormalities, and thyroid disorders
The diagnosis of repeated miscarriages is based on having had 2 or 3 miscarriages.
Treatment of Recurrent Miscarriage
Treatment of the cause if possible
Some causes of repeated miscarriages can be treated, making a successful pregnancy possible.
