What is a miscarriage?
A miscarriage, also called a spontaneous abortion, is the spontaneous ending of a pregnancy. About 1/3 to 1/2 of all pregnancies end in miscarriage before a woman misses a menstrual period or even knows she is pregnant. About 10 to 20% of women who know they are pregnant will miscarry.
A miscarriage is most likely to occur within the first 3 months of pregnancy, before 20 weeks’ gestation. Only 1% of miscarriages occur after 20 weeks’ gestation. These are termed late miscarriages.
What are the risk factors for a miscarriage?
A risk factor is a trait or behavior that increases a person’s chance of developing a disease or predisposes a person to a certain condition. Risk factors for miscarriage include:
- Maternal age. Studies show that the risk of miscarriage is 12% to 15% for women in their 20s and rises to about 25% for women at age 40. The increased incidence of chromosomal abnormalities contributes to the age-related risk of miscarriage.
- Certain health conditions in the mother as listed in the section, "What causes miscarriage?"
Symptoms and Causes
What causes miscarriage?
About half of all miscarriages that occur in the first trimester are caused by chromosomal abnormalities — which might be hereditary or spontaneous — in the father's sperm or the mother's egg. Chromosomes are tiny structures inside the cells of the body that carry many genes, the basic units of heredity.
Genes determine all of a person’s physical attributes, such as sex, hair and eye color and blood type. Most chromosomal problems occur by chance and are not related to the mother’s or father’s health.
Miscarriages are also caused by a variety of unknown and known factors, such as:
- Exposure to environmental and workplace hazards such as high levels of radiation or toxic agents.
- Hormonal irregularities.
- Improper implantation of fertilized egg in the uterine lining.
- Maternal age.
- Uterine abnormalities.
- Incompetent cervix. (The cervix begins to widen and open too early, in the middle of pregnancy, without signs of pain or labor.)
- Lifestyle factors such as smoking, drinking alcohol, or using illegal drugs.
- Disorders of the immune system including lupus, an autoimmune disease.
- Severe kidney disease.
- Congenital heart disease.
- Diabetes that is not controlled.
- Thyroid disease.
- Certain medicines, such as the acne drug isotretinoin (Accutane®).
- Severe malnutrition.
- Group B beta strep.
Note: There is no proof that stress, or physical or sexual activity causes miscarriage.
Sometimes, treatment of a mother’s illness can improve the chances for a successful pregnancy.
What are the symptoms of a miscarriage?
Symptoms of a miscarriage include:
- Bleeding that progresses from light to heavy.
- Abdominal pain.
- Low back ache that may range from mild to severe.
If you are experiencing the symptoms listed above, contact your healthcare provider right away. He or she will tell you to come in to the office or go to the emergency room.
What are some of the symptoms after a miscarriage?
Spotting and mild discomfort are common symptoms after a miscarriage. If you have heavy bleeding, fever, chills, or pain, contact your healthcare provider immediately as these may be signs of an infection.
Diagnosis and Tests
How is a miscarriage diagnosed and treated?
Your healthcare provider will perform a pelvic exam and an ultrasound test to confirm the miscarriage. If the miscarriage is complete and the uterus is clear, then no further treatment is usually required. Occasionally, the uterus is not completely emptied, so a dilation and curettage (D&C) or dilation and extraction (D&E) procedure is performed. During these procedures, the cervix is dilated and any remaining fetal or placental tissue is gently scraped or suctioned out of the uterus. You will usually resume your menstrual period in about 4 to 6 weeks.
If a miscarriage was not confirmed, but you had symptoms of a miscarriage, bed rest is often prescribed for several days, and you might be admitted to the hospital overnight for observation. When the bleeding stops, usually you will be able to continue with your normal activities. If the cervix is dilated, you might be diagnosed with an incompetent cervix, and a procedure to close the cervix (called cerclage) might be performed.
Blood tests, genetic tests, or medicine might be necessary if a woman has more than two miscarriages in a row (called repeated miscarriage). Some diagnostic procedures used to evaluate the cause of repeated miscarriage include:
Outlook / Prognosis
Can I get pregnant after I’ve had a miscarriage?
Yes. Most women (87%) who have miscarriages have subsequent normal pregnancies and births. Having a miscarriage does not necessarily mean you have a fertility problem. About 1% of women might have repeated miscarriages (three or more). Remember that usually a miscarriage cannot be prevented and often occurs because the pregnancy is not normal. Some researchers believe this is related to an autoimmune response.
Although there is no recommended waiting period to attempt pregnancy, it may be appropriate to discuss the timing of your next pregnancy with your healthcare provider. To prevent another miscarriage, your healthcare provider might recommend treatment with progesterone, a hormone needed for implantation in the uterus. If the mother has an illness, treating the condition can improve the chances for a successful pregnancy.
Taking time to heal both physically and emotionally after a miscarriage is important. Above all, don’t blame yourself for the miscarriage. Counseling is available to help you cope with your loss. A pregnancy loss support group might also be a valuable resource to you and your partner. Ask your healthcare provider for more information about counseling and support groups.
If you’ve had three miscarriages in a row, you should stop trying to conceive, use a form of birth control, and ask your healthcare provider about performing diagnostic tests to determine the cause of the miscarriages.