Spontaneous abortion, or miscarriage, is the loss of a fetus before 20 weeks of pregnancy. The most common cause of miscarriage is a genetic abnormality. About one-third to one-half of all pregnancies result in miscarriage. A second miscarriage generally occurs in only 1% of women. However, there are women who experience habitual miscarriages (three or more consecutive spontaneous abortions). Almost one-third of miscarriages may occur as a late menstrual period, even before a woman knows for certain that she is pregnant.

Signs and Symptoms

Miscarriage is often accompanied by the following signs and symptoms:

What Causes It?

A wide range of health conditions that affect at least one parent can cause a miscarriage, including the following:

Who's Most At Risk?

People with the following conditions or characteristics are at risk for having a miscarriage:

What to Expect at Your Provider's Office

If you think you are having a miscarriage, see your healthcare provider. He or she will take a comprehensive medical, family, and social history to try to determine if there is a suggestion of an underlying cause. A pelvic examination detects uterine abnormalities. Ultrasound imaging and other diagnostic and laboratory tests may be used to confirm diagnosis and to evaluate the condition of the uterus and fetus.

Treatment Options


Avoiding known risks, such as caffeine, alcohol, and cigarette smoking, as well as other risks listed above may help prevent miscarriage.

Treatment Plan

Immediate treatment sometimes involves surgery to remove pregnancy tissue. Your healthcare provider may recommend counseling to help you through the grieving process. In vitro fertilization, embryo transfer, or artificial insemination may be used to achieve a successful pregnancy if you have a history of unexplained, recurrent miscarriages.

Drug Therapies

Your healthcare provider may prescribe the following medications to treat underlying conditions or, in the case of repeated miscarriages, to help you achieve a successful pregnancy:

Surgical and Other Procedures

Dilation and curettage (D&C) may be performed to remove pregnancy tissue if it has not been expelled naturally from the uterus. Other surgical procedures may be performed to address uterine problems or adhesions.

Complementary and Alternative Therapies

As indicated in the section, Who's Most At Risk, there appears to be a strong connection between diet, lifestyle, and risk of spontaneous abortion. Before becoming pregnant, therefore, it is a good idea to have counseling about the risks, including the importance of avoiding caffeine, alcohol, and recreational drugs. Also, some case reports suggest Chinese herbal medicines may help prevent recurring miscarriages caused by immune system problems. However, there is no clear scientific evidence of this.

Vitamin B Complex, Including Folic Acid:
Many naturopathic and other doctors suggest using vitamin B complex (50 mg a day) with additional vitamin B6 and folic acid (800 to 1000 mcg a day) for women planning to become pregnant and for those who are pregnant. These preventive measures are supported by studies that suggest a connection between recurring miscarriages and problems metabolizing methionine and homocysteine in the body. Methionine is an amino acid, a building block of protein. Homocysteine is a by-product of the breakdown of methionine. Abnormal use of homocysteine by the body leads to a rise in levels of this compound which, in turn, may play a role in spontaneous abortion and the development of defects in the neural tube (the structure in the fetus that later becomes the central nervous system). Folic acid, vitamins B6 and B12, and betaine all play a role in the proper use of methionine and homocysteine.

In addition, a fetus, a newborn, and a pregnant woman all need more folic acid and B12 than other people; therefore, taking the supplements mentioned both before and during pregnancy is valuable, and may prevent miscarriage in the case of elevated homocysteine levels. Moderate to high caffeine intake may also be related to elevated homocysteine levels.

Some substances—including caffeine and pesticides—easily cross the placenta from the woman's body to her fetus. Their impact on pregnancy is not entirely understood. Caffeine stays in a pregnant woman's body much longer than in non-pregnant healthy adults. It stays in newborns even longer. A study of 3135 pregnant women showed that moderate-to-heavy caffeine users (those who had at least 151 mg daily) were more likely to have late first- or second-trimester spontaneous abortions compared with nonusers or light users. Light caffeine use (1 to 150 mg daily) increased risk for abortion only in women who had a history of previous spontaneous abortion. (One cup of coffee has 107 mg of caffeine, one cup of tea has 34 mg, and one glass of cola has 47 mg, assuming all are caffeinated beverages.) Coffee was the main source of caffeine in moderate-to-heavy users. Light users were more likely to get caffeine from tea and other sources.

In addition, as mentioned in the subsection, Vitamin B Complex, Including Folic Acid, researchers have recently reported that higher caffeine intake may be related to higher levels of homocysteine. This may contribute to the increased risk of spontaneous abortion in moderate coffee drinkers, but further research is needed.

Coenzyme Q10:
Studies suggest that coenzyme Q10 levels are lower in women who have had a recent miscarriage. Similar to methionine and homocysteine described above, the production of coenzyme Q10 in the body also depends on folic acid, vitamin B12, and betaine. Therefore, the same supplements that support methionine metabolism (namely, folic acid, vitamin B12, and betaine) maintain normal coenzyme Q10 levels in the body.

Magnesium and Selenium:
A small study of infertile women and women with a history of miscarriage suggests that low levels of magnesium may impair reproductive function, and may contribute to miscarriage. Oxidation, a process that is damaging to cell membranes, can lead to loss of magnesium. The same study suggests that the antioxidant selenium protects the cell membrane, thereby maintaining appropriate levels of magnesium. The authors of the study suggest taking both magnesium and selenium supplements.

Women who have miscarried have lower levels of selenium than women who carry a pregnancy to full term. Although the authors of the above-mentioned study do not specify the exact amount to take, the recommended doses are generally 300 to 400 mg per day of magnesium and 200 mcg per day of selenium. Check the dosage in your prenatal vitamin and discuss appropriate nutrient supplementation with your healthcare provider.

Other Antioxidants:
Vitamin A, vitamin E, and beta-carotene levels tend to be lower in women who have miscarried as well; these nutrients are generally found in prenatal vitamins. Discuss the pros and cons of their use with your healthcare provider before becoming pregnant or if you are already pregnant.

Fish Pollutants:
Eating fish contaminated with pollutants, namely persistent organochlorine compounds (POCs), may increase pregnancy risk, although it is not clear whether eating contaminated fish contributes to spontaneous abortion.

Western herbs may help clear up underlying endocrine problems. They may also help reduce stress, but these have not yet been studied in relation to spontaneous abortion specifically.

A Chinese and Japanese Herbal Remedy:
There are case reports of recurring spontaneous abortion caused by immune system problems that have been successfully treated with Traditional Chinese Medicine (TCM). Researchers gave Chinese herbs to 12 women, all of whom had had at least two first-trimester miscarriages related to immune function abnormalities. When their immune systems returned to normal as a result of taking this preparation, the women were able to carry their pregnancies to term. If you would like to consider working with an experienced traditional Chinese physician, discuss this possibility with your gynecologist.

No scientific literature supports the use of homeopathy to prevent spontaneous abortion. An experienced homeopath would consider your individual case and may recommend treatments to address your underlying condition and support your overall health.

No scientific literature supports the use of acupuncture to prevent spontaneous abortion. However, many acupuncturists report success in treating women with a history of spontaneous abortion, leading to the ability to carry the pregnancy to full term. This may result from clearing up underlying endocrine problems and reducing stress.

Prognosis/Possible Complications

There is only a 1% chance of recurring miscarriage; however, the risk increases significantly with each subsequent loss. Possible complications from spontaneous abortion include infected pregnancy tissue, which could lead to pelvic abscess, septic shock, or even death. Depression and guilt are common feelings that may follow a miscarriage; as mentioned earlier, there are times when counseling is appropriate.

Following Up

Your healthcare provider will monitor you until the miscarriage is complete. If you have suffered a miscarriage, you should see your provider very soon after any future pregnancies.


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