Miscarriage

Miscarriage is the natural or spontaneous end of a pregnancy at a stage where the embryo or fetus is unable to survive outside the uterus, generally defined in humans at a gestation of less than 20 weeks. Most miscarriages occur very early in the pregnancy, often before a woman even knows she is pregnant.

Miscarriage is the most common complication of early pregnancy. The medical term spontaneous abortion is used in reference to miscarriages because the medical term abortion refers to any terminated pregnancy, whether it is deliberately induced or occurs spontaneously. (In layman's terms, abortion refers specifically to active termination of pregnancy.)

Cross section showing location of uterus in the body. Source: Gray's Anatomy

Other Names

• Spontaneous abortion
• Pregnancy loss

Types

There are several types of miscarriage.

Threatened miscarriage

Early pregnancy may have some spotting (blood in the underwear) that may be associated with cramping. This is called a threatened miscarriage or threatened abortion. It is often actually due to implantation of the embryo into the wall of the uterus. The cervix remains closed, and there may or may not be pregnancy loss after that.

Inevitable or incomplete miscarriage

In an inevitable miscarriage or inevitable abortion, there is vaginal bleeding with abdominal or back pain. The cervix is open, which makes miscarriage inevitable. Bleeding and cramps may continue if the miscarriage is incomplete.

Complete miscarriage

A completed miscarriage or completed abortion is when the products of conception (the medical term for the embryo and associated membranes and tissues) have emptied out of the uterus. Physical symptoms usually subside quickly.

Missed miscarriage

A missed miscarriage or missed abortion refers to a situation where the embryo dies, but it is not shed from the uterus. Signs of this would be a loss of pregnancy symptoms and no heartbeat found on an ultrasound.

Recurrent miscarriage

Recurrent miscarriage is defined as three or more first-trimester miscarriages in a row.

Blighted ovum

A blighted ovum is when a fertilized egg implants into the uterine wall, but a fetus never develops, though the gestational and/or yolk sacs might develop.

Ectopic pregnancy

In an ectopic pregnancy, a fertilized egg implants itself in places other than the uterus, often in the fallopian tube. Ectopic pregnancies are dangerous and need to be terminated promptly, because as the embryo and its blood supply grow, the pregnancy is at risk of rupturing, causing life-threatening bleeding and sometimes the death of the mother.

Molar pregnancy

A molar pregnancy is the result of a genetic error during the fertilization process that leads to growth of abnormal tissue within the uterus. Molar pregnancies generally do not have an embryo, but still have the common symptoms of pregnancy, including a missed period, positive pregnancy test, and severe nausea.

Septic miscarriage

Some women who have miscarriage develop an infection in the uterus; this is called a septic miscarriage or septic abortion. "Back-alley" abortions done by nonprofessionals under non-sterile conditions often lead to this type of infection, which may end a woman's life.^[1][2] Symptoms include fever, chills, abdominal pain, vaginal bleeding, and vaginal discharge, which may be thick and have an unpleasant odor.

Symptoms

Signs of a miscarriage can include:

• Vaginal spotting or bleeding
• Cramping, abdominal pain, or back pain
• Fluid or tissue passing from the vagina

Although vaginal bleeding is a common symptom when a woman has a miscarriage, many pregnant women have spotting early in the pregnancy without miscarrying.

Causes

There are many different causes of miscarriage, some known and others unknown. In most cases, there is nothing a woman can do to prevent a miscarriage. A great many early pregnancies end spontaneously.

There are some factors that may contribute to miscarriage.

• Chromosomal defect. The most common cause of miscarriage in the first trimester is a chromosomal abnormality in the fetus. This usually results from a problem with the sperm or egg that prevents the fetus from developing properly.
• Cervical/uterine problems. During the second trimester, problems with the uterus or cervix can contribute to miscarriage.
• Hormones. Thyroid disorders or low progesterone (progesterone is needed to maintain the pregnancy until the placenta takes over) can lead to early miscarriage.
• PCOS. Women with a disorder called polycystic ovary syndrome are three times more likely to miscarry during the early months of pregnancy than women who don’t have the syndrome.
• Infection. For example, chicken pox, fifth disease (known as "slapped cheek" in children), malaria, syphilis, or toxoplasmosis (which can be picked up from cleaning the litterbox of a cat).
• Immune disorders.
  • Antiphospholipid antibodies cause blood clotting in the placenta, leading to miscarriage. These can be tested for with a blood test. Those who have the antibodies can sometimes be successfully treated with blood thinners to prevent further miscarriages.
  • Antinuclear antibodies like those present in patients with lupus cause an autoimmune problem in which the body attacks itself.
  • In some rare cases, the mother's body creates antibodies against the genetic material of the father, causing the immune system to attack and lead to miscarriage early in the pregnancy.
• Substance abuse. Women who use cocaine during pregnancy have an increased risk of miscarriage.

Diagnosis

If there is bleeding and cramping during the first 20 weeks of pregnancy, a physical exam will help determine whether a miscarriage has occurred. The doctor will examine the cervix to determine whether it is open (dilated). A closed cervix means there is a chance there will not be a miscarriage, but an open cervix makes miscarriage likely.

An ultrasound is usually also performed to see whether a miscarriage has already occurred, or whether the fetus is still alive. If a miscarriage has occurred, ultrasound can show whether the fetus and the placenta have passed from the uterus.

Treatment

There are several ways to treat miscarriage. The method used depends on the individual woman's situation.

Observation

Sometimes, women having a miscarriage require no further treatment other than follow-up. This includes many women with complete miscarriage, and women who miscarry at less than 13 weeks' gestation (first trimester) who are stable. Usually within 2 weeks (but sometimes as much as a month), the products of conception pass from the uterus on their own. Once this has happened, an ultrasound is generally done to make sure the miscarriage is complete.

Medical treatment

In some situations, medications can be given to stimulate the uterus to pass the pregnancy tissue sooner. The medicine can be given by mouth or vaginally, and works over several days.

Surgical treatment

Commonly, early miscarriage is treated with a surgical procedure called dilation and curettage, or "D and C." The cervix is dilated and contents of the uterus are suctioned. Some women prefer a D and C so that the miscarriage is completed sooner, rather than potentially waiting for several weeks for the tissue to pass on its own. D and C is also used for women who have heavy bleeding or infection as a result of the miscarriage.

Prevention

Many miscarriages that are caused by systemic diseases can be prevented by detecting and treating the disease before becoming pregnant.

Miscarriages are less likely in women who receive early, comprehensive prenatal care and avoid environmental hazards (such as radiation and infectious diseases). Avoiding smoking, alcohol, and substance abuse can also decrease the risk.

When a mother's body is having difficulty sustaining a pregnancy, signs (such as slight vaginal bleeding) may occur. This is a threatened miscarriage or threatened abortion, which means there is a possibility of miscarriage, but it does not mean one will definitely occur. There is some debate about whether any particular treatment is needed for a threatened miscarriage, with some doctors advising that patients should avoid sexual intercourse and should rest in bed. The former prescription has not been studied, but bed rest has been studied and there appears to be no benefit and some risk of harm.^[3]

Chances of Having a Miscarriage

For most healthy women, there is about a 15-20% chance of having a miscarriage. As women age, their chances of having a miscarriage increase, as shown with the following statistics from the American Pregnancy Association:

• Women under 35 yrs old have about a 15% chance of miscarriage
• Women 35-45 yrs old have a 20-35% chance of miscarriage
• Women over 45 can have up to a 50% chance of miscarriage
• Previous miscarriage increases risk of another to a 25% chance (only slightly higher than the risk of the average woman)

Risk factors

Although the exact cause of many miscarriages cannot be pinpointed, there are several things that are considered risk factors for miscarriage:

• Age: Older women are more likely to have a miscarriage than younger women.
• Number of pregnancies: Women who have been pregnant two or more times have an increased risk of miscarriage.
• Previous miscarriage: Having a miscarriage in the past increases the risk for a future miscarriage.
• Smoking: There is evidence that smoking, especially more than 10 cigarettes a day, increases the risk of miscarriage.^[4][5]
• Alcohol: Some studies show an association between drinking alcohol and increased miscarriages. No amount of alcohol is known to be safe during pregnancy.
• Fever: Pregnant women who develop a fever appear to have an increased risk of miscarriage.
• Trauma: Trauma to the uterus can increase the risk of miscarriage.
• Caffeine: In one study, some women who ingested the amount of caffeine equivalent to about four or more 8-ounce cups of coffee a day had an increased risk of miscarriage.^[6]
• Other causes: Women who are exposed to certain substances or conditions may have an increased risk of congenital abnormalities and miscarriage. This includes exposure to certain infections, medications, drugs, radiation, physical stresses, and environmental chemicals.

Related Problems

Complications

Complications in the mother are rare. However, possible complications include infection, which may need to be surgically treated.

Women who lose a pregnancy during the second or third trimester of pregnancy receive different medical care than those who lose it in the first trimester. If the dead fetus remains in the uterus for too long, blood clotting can develop, threatening the mother's health, so the need to remove the products of conception is more urgent.

Emotional health

The loss of a pregnancy is often devastating for a woman and her partner. Associated grief is common and normal. Because the pregnancy is usually most real to the woman and her partner, while others have not yet formed an attachment to the coming baby, the grief may feel unsupported or ignored by others. Counseling and support groups may help parents during this sad time. Profound sadness continuing more than two weeks beyond the loss may be a sign of depression.

Clinical Trials

For a list of completed, ongoing, and upcoming American government-sponsored clinical trials related to pregnancy loss, go to ClinicalTrials.gov.

Research

The NICHD (National Institute of Child Health and Human Development) supports and conducts research on the causes of miscarriage in hopes of finding ways to prevent women from having them. For instance, NICHD-supported researchers recently found that women with a disorder called polycystic ovary syndrome (PCOS) are three times more likely to miscarry during the early months of pregnancy than women who don't have PCOS. Women with PCOS often have great difficulty getting pregnant naturally.

Research has found that women with PCOS also tend to have a condition called insulin resistance, which means their bodies have trouble using the insulin they make to get energy from their cells. Insulin resistance often occurs before someone develops diabetes. To treat this insulin resistance, researchers had been prescribing a drug called metformin. What they found was that metformin not only reduced insulin resistance, but it also brought about changes to the uterine lining that could help women with PCOS get pregnant and reduce the risk of miscarriage during the first trimester (the first 3 months) of pregnancy.

Studies are now underway to confirm the positive effects of using metformin in women with PCOS, and to evaluate the safety of taking the drug throughout pregnancy. The NICHD's Reproductive Sciences Branch, through its Reproductive Medicine Network (RMN) is currently conducting a clinical trial for the treatment of infertility related to PCOS, using metformin. The RMN Web site provides more information on this trial and on the RNM itself.

Other NICHD-supported research is being conducted to learn more about repeated miscarriage. Researchers estimate that between 1% and 2% of women in the United States have more than one miscarriage without a known cause. Women who experience repeated miscarriages may undergo expensive and lengthy tests to try to identify a cause, but often get no answers. NICHD researchers, examining the vulva of these women, have found that many of them share a genetic mutation, or change. This mutation, on one of the X chromosomes, was found in nearly 15% of women who had a history of repeated, unexplained miscarriage. If this genetic mutation is confirmed as a cause of repeated miscarriages, researchers may be able to develop a simple blood test that could predict a woman's chances of having a miscarriage in future pregnancies.

For more information on NICHD-supported research on miscarriage, read the Institute's news releases on miscarriage. The National Library of Medicine provides additional information on pregnancy loss, which includes miscarriage.

Expected Outcome

Women who have miscarriages can and often do become pregnant again, with normal pregnancy outcomes.

References

1. ↑ Sood M, Juneja Y, Goyal U. Maternal mortality and morbidity associated with clandestine abortions. J Indian Med Assoc. 1995 Feb;93(2):77-9. Abstract
2. ↑ Rana A, Pradhan N, Gurung G, Singh M. Induced septic abortion: a major factor in maternal mortality and morbidity. J Obstet Gynaecol Res. 2004 Feb;30(1):3-8. [1]
3. ↑ Tien JC, Tan TY. Non-surgical interventions for threatened and recurrent miscarriages. Singapore Med J. 2007 Dec;48(12):1074-90; quiz 1090. Abstract | PDF
4. ↑ Kline J, Stein ZA, Susser M, Warburton D. Smoking: a risk factor for spontaneous abortion. N Engl J Med. 1977 Oct 13;297(15):793-6. [2]
5. ↑ Chatenoud L, Parazzini F, di Cintio E, Zanconato G, Benzi G, Bortolus R, La Vecchia C. Paternal and maternal smoking habits before conception and during the first trimester: relation to spontaneous abortion. Ann Epidemiol. 1998 Nov;8(8):520-6. Abstract
6. ↑ Bech BH, Nohr EA, Vaeth M, Henriksen TB, Olsen J. Coffee and fetal death: a cohort study with prospective data. Am J Epidemiol. 2005 Nov 15;162(10):983-90. Epub 2005 Oct 5. Abstract

External Links

• Daily Strength: Miscarriage Support Group

• HopeXchange: Miscarriage Support

• American Pregnancy Association: Miscarriage