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Miscarriage

Miscarriage is the most common type of pregnancy loss, according to the American College of Obstetricians and Gynecologists. Anywhere from 10 to 25 percent of all known pregnancies end this way, and more than 80 percent of these miscarriages occur within the first 12 weeks. There is a lot of debate over the actual rate of miscarriage, however, because you may have one before you even know you're pregnant. In these cases, the loss usually goes undocumented. When these unrecognized losses are taken into consideration, the estimated rate of miscarriage is anywhere from 50 to 75 percent.

Causes of Miscarriage

A miscarriage (technically called a spontaneous abortion) is a pregnancy that ends on its own within the first 20 weeks of gestation, and occurs when the fetus and placenta separate from the uterine wall. While the causes of miscarriage are not well understood, there are several factors believed to contribute to their occurrence.

Chromosomal abnormalities

The most common reason for the loss of a pregnancy during the first trimester is chromosomal abnormality, which means something is wrong with the chromosomes of the embryo. Chromosomes are the tiny structures in each of our cells that carry our genes, which dictate everything from the color of our eyes to the functioning of our internal organs. We all have 23 pairs of chromosomes, or 46 total, with one chromosome per pair coming from our mothers and one from our fathers. Defects in chromosomes are found in more than half of miscarriages occurring in the first 13 weeks.

Chromosomal abnormalities occur before pregnancy when immature egg and sperm cells divide unevenly. Rather than form with 23 chromosomes, the mature egg or sperm cells end up with too many or too few. With the wrong number of chromosomes, the embryo has an abnormality and is usually miscarried. Miscarriages are said to eliminate about 95 percent of fertilized eggs or embryos with genetic problems, which could be nature's way of ending a pregnancy in which the child would have been unable to survive. Most chromosomal problems happen by chance, have nothing to do with you or your partner, and are unlikely to recur.

Below are the most common chromosomal defects.

• Trisomy - Trisomy is a condition that occurs when instead of 23 matched pairs of chromosomes, there are 22 pairs plus one set of three. Most fetuses with trisomy are miscarried during the first trimester. Of those who do survive, most have Down syndrome, also called trisomy 21 because they have a third chromosome 21. Others who survive with trisomy may have trisomy 13 or 18, which are almost always associated with profound mental retardation and other serious malformations at birth. These babies rarely live more than a few days or months.



• Monosomy - Monosomy is having a single copy of a particular chromosome, rather than the usual pair. Sometimes when an egg or sperm cell is forming, an error will cause it to have a missing sex chromosome. Only 1 percent of these pregnancies will survive. Female babies who are born with only one X chromosome have a condition called Turner syndrome. This condition, also known as monosomy X, occurs in one in every 2,500 female newborns, causing them to be shorter than their peers and to not mature sexually as they become adults.



• Polyploidy - Polyploidy occurs when cells contain more than two copies of each of their chromosomes. This may be a result of an egg being fertilized with more than one sperm. Additional chromosomes can cause multiple anomalies, such as defects of the heart and central nervous system. There is no chance for long-term survival, and most of these cases end in miscarriage.

Illness or Infection

A miscarriage after 20 weeks of gestation is then referred to as a stillbirth. When these losses occur, they are more likely due to maternal factors, such as an illness, than chromosomal abnormalities in your baby.

Diseases like diabetes, when poorly controlled, put women at great risk for miscarriage. If you have diabetes and it is under control with treatment, however, you are no more likely to lose a pregnancy than any other woman. Other illnesses and conditions believed to increase the risk of miscarriage include systemic lupus erythematosus (lupus), high blood pressure, and certain infections, such as rubella, mycoplasma (walking pneumonia), toxoplasmosis, herpes simplex and chlamydia. A 2003 study found that women with an infection called bacterial vaginosis were nine times more likely to have a miscarriage than uninfected women.

Hormonal Imbalance

When your body produces too much or too little of certain hormones, your risk of having a miscarriage may increase. Progesterone, a crucial hormone for supporting an early pregnancy, prepares the lining of your uterus to nourish a fertilized egg. If your body doesn't make enough progesterone and the lining of your uterus cannot sustain an egg, your pregnancy may end in miscarriage. Although it hasn't been proven, some researchers believe low levels of progesterone cause between 25 and 40 percent of early miscarriages. A blood test and a biopsy can determine whether your body is producing enough progesterone, and if you have low levels in repeated cycles, you have what is called a luteal phase defect.

High levels of luteinizing hormone (LH) can also affect the quality of your eggs and any resulting embryos. This hormone defect is common in women with polycystic ovarian syndrome (PCOS), a condition characterized by multiple cysts on the ovaries, which may also result in early miscarriage. Systemic maternal endocrine disorders, such as diabetes mellitus and thyroid disease, have also been associated with miscarriage.

Abnormalities of the Uterus and Cervix

Diseases and abnormalities of your internal organs can also lead to miscarriage. Some women are born with a misshapen uterus, while others may develop non-cancerous growths made of muscle tissue called fibroids, or may have scars in their uterus from past surgery. Abnormalities like these can limit space for the growing fetus or interfere with the blood supply to the uterus. An incompetent cervix (a cervix that is too weak to stay closed during pregnancy) can also cause preterm birth and possibly loss of the baby. Although the condition is rare, if a weakened cervix dilates too early in pregnancy, it can result in the expulsion of the fetus from the uterus without labor or any contractions.

According to the American College of Obstetricians and Gynecologists, uterine defects are estimated to cause about 15 percent of all miscarriages, although some can be surgically corrected, improving the outlook for future pregnancies. After surgery for uterine abnormalities, 70 to 90 percent of pregnancies are successful.

Autoimmune Disorders

Autoimmune problems occur when certain chemicals in the bloodstream attack cells and tissues inside the body. While we all produce antibodies to fight off infections, some of us also produce auto-antibodies, which attack a person's own tissues and may cause a variety of health problems from diabetes to hypothyroidism. Women whose blood contains these types of antibodies are at particularly high risk for miscarriage because the antibodies can cause blood clots to form in the placenta, shutting off blood supply to the fetus.

A blood test can measure antibody levels to determine if you have this disorder. Low doses of aspirin and a blood-thinning drug called heparin have been known to help 70 to 75 percent of women with this disorder deliver healthy babies.

Lifestyle Factors

While most miscarriages are caused by chromosomal abnormalities and other physical factors you cannot control, your lifestyle may also increase your risk of a first-trimester miscarriage. The American College of Obstetricians and Gynecologists states that drinking alcohol, smoking cigarettes and using illicit drugs during your pregnancy may all increase your risk. Get as healthy as you can before conceiving so that you'll be able to provide a healthy place for your baby to grow.

Below are a few steps you can take to minimize your risk of having a miscarriage.

• Don't smoke - Smoking is known to increase the risk of losing a genetically healthy baby. One study showed that women who smoked more than 14 cigarettes a day were about twice as likely to miscarry. Secondhand smoke is also dangerous, so no one else should smoke around you while you are pregnant.



• Stay away from alcohol - Studies show that having an alcoholic beverage twice a week doubled the risk of miscarriage, while drinking every day tripled the risk.



• Don't drink a lot of caffeine - In large amounts (more than 4 cups of coffee per day), caffeine has been shown to slightly increase the chance of miscarriage. The more caffeine consumed, the higher the risk, so doctors generally recommend no more than one cup of coffee per day.



• Avoid radiation and toxic substances - Various levels of radiation and toxic substances, such as arsenic, lead, formaldehyde, benzene and ethylene oxide, can cause miscarriage. Make sure you are not exposed to any of these at work or anywhere else.



• Prevent trauma to the abdomen - Avoid contact sports or activities that may cause injury and don't participate in sports in which you could fall. Steering wheel and seatbelt injuries can also cause miscarriage if they are positioned incorrectly.



• Check with your doctor before taking any medicine - Some prescription and over-the-counter drugs are associated with fetal abnormalities and miscarriages. One study suggested that women who use pain-relieving medications such as ibuprofen and aspirin around the time of conception may also increase their risk of miscarriage. Ask your doctor which medications you may take without putting your baby at risk.

Types of Miscarriages

Because it is often a process and not a single event, there are many different stages or types of miscarriage that can occur.

• Threatened Miscarriage - When a woman shows physical signs that she may be experiencing a miscarriage, it is called a threatened miscarriage. This is characterized by some degree of uterine bleeding and either cramping or lower back pains. It is often hard to tell if these signs are the beginning of an inevitable miscarriage in which the bleeding continues and the pregnancy is lost, or if this bleeding simply early pregnancy spotting as a result of implantation. During a threatened miscarriage, the cervix remains closed. If it opens, the miscarriage becomes inevitable.



• Inevitable Miscarriage - An inevitable miscarriage occurs when the loss of a pregnancy is imminent. This could happen soon after a threatened miscarriage or suddenly, without warning. Symptoms of an inevitable miscarriage include bleeding, abdominal or back pain, a dilated cervix and rupture of membranes. Uterine contractions to expel the fetus usually begin soon after these symptoms develop. If the miscarriage is not complete, bleeding and cramping may continue.



• Missed Miscarriage - It is possible for a woman to have a miscarriage without knowing it. Sometimes after a fetus has died, the cervix stays closed and there is no bleeding at first, and the body does not naturally discharge of it or any other physical elements of the pregnancy for several weeks. This is called a missed miscarriage. Signs of this include a loss of pregnancy symptoms and the absence of a fetal heartbeat during an ultrasound. Sometimes a woman is unaware that she's miscarried for days or weeks. A woman who has had a missed miscarriage may choose to wait and see if her pregnancy miscarries naturally, or have an operation to empty her uterus. While any kind of miscarriage can be emotionally devastating, missed miscarriages may be the hardest for a woman to understand and accept.



• Chemical Pregnancy - A chemical pregnancy occurs when the egg is fertilized, but dies shortly after implantation. This is usually due to a chromosomal defect in the embryo. In most cases, a pregnancy test will give a positive result before a period has been missed, but it will come a few days later. The bleeding is similar to a heavy menstrual period. Very early miscarriages like these are thought to be quite common. An estimated 50 to 60 percent of first pregnancies end this way. If a home pregnancy test isn't taken, most women never know they were pregnant.



• Blighted Ovum - A blighted ovum is another common type of miscarriage that occurs when the fertilized egg implants itself into the uterus, but the cells do not continue to divide or develop to create a baby. As with a chemical pregnancy, a woman will receive a positive result from a pregnancy test and may experience pregnancy symptoms, but will usually miscarry anywhere from 7 to 12 weeks later. Similar to a missed miscarriage, a blighted ovum may not be discovered for several weeks, but can be detected with an early ultrasound. In this case, the woman will have the option to have an operation to empty the uterus, or wait for her miscarriage to happen naturally.



• Ectopic Pregnancy - When a fertilized egg implants itself outside the uterus, it is called an ectopic pregnancy. About 98 percent of ectopic pregnancies occur in the fallopian tube and are discovered at about six or seven weeks. About 1 percent of pregnancies are ectopic, but up to 50 percent of these are estimated to spontaneously miscarry and appear like early, inevitable miscarriages. The other 50 percent of women with ectopic pregnancies will experience symptoms, such as vaginal spotting, pain the lower abdomen, a bloated belly and dizziness or fainting. An ultrasound or vaginal exam can confirm an ectopic pregnancy. Depending on the size and location of the embryo, a doctor will determine the best form of treatment for an ectopic pregnancy, either an injection or surgery.



• Molar Pregnancy - A molar pregnancy is the result of a genetic error during the fertilization process that leads to abnormal tissue growth in the uterus. In the case of a molar pregnancy, a woman misses her period and experiences the normal physical signs of pregnancy, but there is rarely a baby developing. At some point during the first few weeks of a molar pregnancy, part of the placenta starts to produce fluid filled cysts that multiply rapidly. A routine ultrasound between 18 and 20 weeks should be able to detect this problem if it exists. Molar pregnancies only occur in 1 out of every 1,000 pregnancies.

Miscarriage Symptoms

It is not always easy to tell if you are having a miscarriage because it can occur in a chain or events over several days. One woman's experience can be very different from another's experience. If you are pregnant and notice any or all of the following symptoms, call your doctor or get to a medical facility as soon as possible.

• Vaginal bleeding or spotting
• Passing tissue or blood clots from the vagina
• Pain and cramping in the lower abdomen
• Persistent lower back pain
• Loss of pregnancy symptoms (nausea, breast tenderness, etc.)

Recurrent Miscarriage

Recurrent miscarriage is defined as three or more pregnancy losses before 20 weeks of gestation. While miscarriage is usually a one-time occurrence, the American Journal of Obstetrics and Gynecology states about 1 to 2 percent of couples experience two or more miscarriages in a row, and the risk increases significantly with each subsequent loss.

If you have had two or more miscarriages, you and your partner should have complete medical evaluations to learn the cause and how you can prevent another one. Testing can determine the cause of recurrent miscarriages in at least 75 percent of couples.

Below are some of the conditions that are known to cause recurrent miscarriages and the percentage of cases in which they occur.

• Chromosomal abnormality in one member of the couple - 5 to 10%
• Uterine abnormalities - 10 to 15%
• Hormone problems - 5 to 40%
• Immune system problems - 5 to 10%
• Unknown causes - 25%

Treatment and Recovery

In most cases of miscarriage in early pregnancy, treatment includes the removal of the fetus and other tissues from the uterus if the body has not passed them naturally. This procedure is called a dilatation and curettage (D&C) and is performed under general anesthesia. Sometimes the tissue is sent to the laboratory and tested for genetic or chromosomal abnormalities. Unless an infection forms, miscarriage does not generally cause serious medical problems.

It can take several weeks to a month or more for a woman to physically recover from a miscarriage, depending on how long she was pregnant. It usually takes much longer to recover emotionally. Grief, anger, numbness and depression are natural emotions a couple may experience after losing a baby.

If you have had a miscarriage and need someone to talk to, don't hesitate to seek counseling or a support group for someone who is experienced with pregnancy loss and understands what you're going through.

Pregnancy After Miscarriage

Making decisions about future pregnancies after a miscarriage can be difficult. After the heartbreak of losing a baby, you and your partner may want to try again as soon as possible, but you might also worry about the possibility of another miscarriage. Fortunately, at least 85 percent of women who have had one miscarriage will go on to have a successful pregnancy, as will about 75 percent of women who have had two or three miscarriages.

There is no perfect time to get pregnant again after a miscarriage, but be sure you're ready both physically and emotionally. Some doctors recommend you wait between three and six months before trying again; most recommend you have at least one normal period. Research suggests that the risk of miscarriage in your next pregnancy is about one and a half times higher if you don't allow yourself one normal menstrual cycle before you try again. However, it could take longer before you feel emotionally ready. Deciding when to attempt another pregnancy is a decision only you and your partner can make.