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A miscarriage is an intensely sad and frightening experience. A pregnancy that had seemed normal suddenly ends, leaving parents devastated. This tragedy occurs in about 15 to 20 percent or approximately 1 in 4 pregnancies.

A miscarriage is a pregnancy loss that occurs prior to 20 weeks, before the fetus is able to survive outside its mother's womb. Most miscarriages occur in the first trimester or 12 weeks of pregnancy. Some doctors believe that as many as 50 percent of all pregnancies end in miscarriage, because some losses occur before a woman realizes she is pregnant.

Why do miscarriages occur?

The causes of miscarriage are not thoroughly understood. When a woman has a first-trimester miscarriage, her doctor often cannot determine the cause. However, most miscarriages occur when a pregnancy is not developing normally. Usually, there is nothing a woman or her doctor can do to prevent it.

There are a number of factors that are known to cause first-trimester miscarriages.

The most important of these is a chromosomal abnormality in the fetus. Chromosomes are the tiny thread-like structures in each cell that carry our genes, which dictate all traits from eye color to the workings of our internal organs. Each person has 23 pairs of chromosomes, or 46 in all, with one chromosome per pair coming from the mother and one from the father. Up to 70 percent of first-trimester miscarriages are caused by chromosomal abnormalities in the fetus.

Most chromosomal abnormalities result from a faulty egg or sperm cell. Before pregnancy, egg and sperm cells divide to form cells with 23 chromosomes. Some-times, the cell splits unevenly in egg or sperm cells with one too many or one too few chromosomes. If a pregnancy occurs involving an egg or sperm cell with the wrong number of chromosomes, the embryo has a chromosomal abnormality. These embryos often do not survive, leading to miscarriage. Chromosomal abnormalities become more common as a woman ages, which is why women over age 35 are at higher risk of miscarriage than younger women.

Chromosomal abnormalities also can result in a blighted ovum - a pregnancy sac that contains no fetus, either because the embryo did not form or because it stopped developing very early. In the early weeks of pregnancy, the woman may notice that her pregnancy symptoms have stopped and she may develop dark-brown vaginal bleeding. An ultrasound examination will show an empty pregnancy sac. A blighted ovum will eventually result in miscarriage, though miscarriage may not occur for weeks. Because waiting for a miscarriage is traumatic, doctors generally recommend emptying the uterus with a procedure called a D&C (dilation and curettage).

In most cases, when a woman has a first miscarriage in the first trimester of pregnancy, her doctor will tell her that the cause was most likely a chromosomal abnormality.

However, other factors also can contribute to first-trimester miscarriage. These can include hormonal problems, infections, and health problems of the mother.

A mother's lifestyle also can increase her risk of a first-trimester miscarriage.

Studies suggest that women who have two or more alcoholic drinks a day double their risk of miscarriage.

Women who smoke cigarettes have a 20 to 80 percent greater risk of miscarriage than nonsmokers.

Some studies also suggest that women who drink three or more cups of coffee a day (or the equivalent amount of caffeine) are at increased risk.

Second-trimester miscarriage often is caused by problems with the uterus (such as an abnormally shaped uterus) or by a weakened cervix that dilates prematurely. As with first-trimester losses, maternal infections and chromosomal abnormalities can cause miscarriage. Chromosomal abnormalities appear to cause up to 20 percent of second-trimester miscarriages.

Certain immune system problems also can cause these losses.

Factors that DO NOT increase the risk of miscarriage include sex, working outside the home (unless a woman works with harmful chemicals), and exercise.

What tests are done following a miscarriage?

Doctors usually perform no tests following a first miscarriage that occurs in the first trimester. The cause of these early losses is often unknown. However, if possible, a woman who is having a first-trimester miscarriage should try to save the tissue from the miscarriage. Some doctors now recommend that the tissue be tested to confirm that a chromosomal abnormality caused the miscarriage.

If a woman has a miscarriage in the second trimester, doctors often are able to determine the cause. Her doctor may recommend some tests, including blood tests, to discover the cause of the loss.

What causes repeated miscarriages?

While miscarriage is usually a one-time occurrence, up to 1 in 20 couples experience two miscarriages in a row, and 1 in 100 have three or more. In some cases, these couples have an underlying problem that is causing the miscarriages. Women who have experienced two or more miscarriages should have a complete medical evaluation to learn the cause of the miscarriages, and what can be done to prevent another one. Testing can reveal the cause of repeat miscarriages in at least 75 percent of couples.

In recent years, doctors have learned a great deal about why some couples have repeated miscarriages and how to prevent them. Some of the more common known causes include:

Chromosomal problems - While past studies have suggested that chromosomal problems usually occur only once, more recent studies suggest that chromosomal problems may cause as many as 60 percent of repeated losses. Most parents who suffer repeated miscarriages have normal chromosomes; however, there is a 5 percent chance that either partner carries a chromosomal rearrangement that does not affect his or her health, but can cause chromosomal abnormalities in the fetus that can result in miscarriage. A blood test (karyotype) is recommended to check for these chromosomal rearrangements.

Uterine abnormalities - Abnormalities of the uterus cause 15 to 30 percent of repeated miscarriages. These miscarriages can occur in the first or second trimester. Some women are born with a uterus that is too small or abnormally shaped or partly or completely divided. Others develop noncancerous tumors (fibroids) or have scars in the uterus from past surgery. These abnormalities can limit space for the growing fetus or interfere with the blood supply to the uterus. Uterine abnormalities are diagnosed with one or more of several methods of viewing the uterus, including ultrasound, an X-ray of the uterus, or hysteroscopy (looking at the uterus through a special scope inserted through the cervix). Many can be surgically corrected, sometimes during the diagnostic procedure, greatly improving the outlook for future pregnancies. A weakened (sometimes called incompetent) cervix (base of the uterus) can lead to miscarriage, usually between 16 and 18 weeks of pregnancy. Repeated miscarriage due to weakened cervix often can be prevented by placing a stitch in the cervix early in the next pregnancy.

Endocrine causes - When endocrine glands secrete too much or too little of certain hormones, the risk of mis-carriage increases. Low levels of the hormone progesterone, which is crucial to support an early pregnancy, are believed to cause between 15 and 60 percent of losses that occur prior to 10 weeks of pregnancy. Women who have low levels of progesterone in repeated menstrual cycles have what is called a luteal phase defect. This is diagnosed by endometrial biopsy (suctioning a small piece of uterine lining to check progesterone levels) or repeated blood tests of progesterone levels. Treatment with the fertility drug clomiphene citrate or natural progesterone suppositories often can prevent another miscarriage.

Immune system problems - While everyone produces proteins called antibodies to fight off infections, some people produce antibodies (called autoantibodies) that can attack their own tissues, causing a variety of health problems. Particular types of auto-antibodies (such as anticardiolipin) cause blood clots that can clog blood vessels in the placenta. Studies suggest that this and related antibodies (called antiphospholipid antibodies) cause between 5 and 15 percent of repeat miscarriages. Special blood tests can measure antibody levels. Treatment with low doses of aspirin and the blood-thinning drug heparin result in a healthy baby in 70 to 80 percent of affected women. Researchers also are studying whether other immune system problems may cause a woman's body to reject her fetus as foreign tissue.

Infections and other factors - Certain symptomless infections of the genital tract play a role in repeated miscarriages. If an infection is diagnosed, the couple will be treated with antibiotics prior to another pregnancy. Work-place exposure to certain industrial solvents, by the pregnant woman or her partner, may sometimes cause miscarriage. Couples should discuss chemicals in their workplace with their health care provider.

In about 25 percent of cases, the cause of repeated miscarriages cannot be found. However, couples in this situation should not lose hope: even without treatment, about 60 percent of women with repeated miscarriages eventually have a healthy pregnancy.

How long does it take to recover from a miscarriage?

It takes weeks to a month or more for a woman to recover physically, depending on how long she was pregnant. For example, some pregnancy hormones remain in the blood for one to two months after a miscarriage. Most women experience a menstrual period four to six weeks after a miscarriage.

Often, it takes much longer to recover emotionally. Women and their partners may experience intense grief as they mourn their loss. A woman may experience many emotions including numbness, sadness, guilt, difficulties concentrating, depression and anger. She and her partner may handle their grief in different ways, creating tension between them at a time when they need each other most. They should not hesitate to ask their health care pro-vider for a referral to a counselor who is experienced with dealing with pregnancy loss. Many couples benefit from support groups, where they can share their feelings with others who have lost a pregnancy.

How long should a woman wait after a miscarriage before attempting another pregnancy?

A woman should not attempt to become pregnant again until she is physically and emotionally ready. Medically, it appears safe to conceive after a woman has had one normal menstrual period (if she is not undergoing tests or treatments for the cause of her miscarriage).

However, it may take much longer before a woman feels emotionally ready to attempt pregnancy. Only she can tell when her grief has eased and she is ready to welcome another child.

Many women who have experienced miscarriage worry that they will miscarry again. Fortunately, at least 85 percent of women who have had one miscarriage will go on to have a successful pregnancy the next time, as will 75 percent of those who have experienced two or three losses.

Some women should consult a specialist before they attempt to conceive. If a woman has had two or more miscarriages (especially if she is over age 35), or if she has an illness (such as diabetes or systemic lupus erythematosus) that can affect her pregnancy, or has had fertility problems, she should see an expert in high-risk pregnancy. Her health care provider can refer her to the appropriate specialist in maternal fetal medicine or reproductive endocrinology. These experts can recommend the most appropriate tests prior to another pregnancy, so that the woman can receive the best treatment to increase her chances that the next pregnancy will be a healthy one.

Also, remember that men, women and children greive in different ways and in different time frames. Seeking support in the form of couselling, groups, and the like is not only recommended by Robyn's Nest, it's encouraged. The following organizations are here to help:

Hygeia Foundation
Bonnie Babes Foundation
March of Dimes Foundation
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These organizations can help you find support in your hometown, online support, provide brochures and reading materials, international resources and much more FREE of charge.

RELATED TOPICS:
Stillbirth
Heath and Safety Links

Miscarriage/Loss Bookshelf
Connecticut Resources

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