Miscarriage is the loss of a pregnancy in the first 20 weeks. About 10 to 20 percent of known pregnancies end in a miscarriage, and more than 80 percent of these losses happen before 12 weeks.
This doesn’t include situations in which you lose a fertilized egg before a pregnancy becomes established. Studies found that 30 to 50 percent of fertilized eggs are lost before or during the process of implantation often so early that a woman goes on to get her period at about the expected time.
Types of Miscarriage
If you think you may have had a miscarriage, your doctor will use a number of terms to explain what has happened:
- If a pregnant woman has bleeding, a little or no pain, a closed cervix, and found to still have a fetus with a heartbeat in her uterus, she may have a threatened abortion. Most pregnancies with an early bleeding but with a detectable heartbeat turn out fine.
- If you have miscarried, your doctor may say that you have a blighted ovum, which is a miscarriage that has occurred so early that no clearly defined fetal tissues have formed.
- An inevitable miscarriage is when the bleeding and cramping occur during pregnancy, with an open cervix.
- An incomplete miscarriage, is when a miscarriage has occurred, but the body does not expel all the tissue from the pregnancy.
- A complete miscarriage, is when all of the tissue from the pregnancy is expelled by the body.
- A missed miscarriage is when the fetus has died or has not been developed, but the body does not discharge the fetus or tissues from the pregnancy. Sometimes, women with missed miscarriages notice that they no longer “feel pregnant.”
What Causes Miscarriage?
The causes of miscarriage are not well understood. Most miscarriages that occur in the first trimester are caused by chromosomal abnormalities in the baby. Chromosomes are the tiny structures inside the cells of the body which carry many genes. Genes will determine all of a person’s physical attributes, such as hair and eye color, sex, 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 other factors, such as:
- exposure to an environmental and workplace hazards such as high levels of radiation or toxic agents
- Hormonal problems
- Uterine abnormalities
- Incompetent cervix (the cervix begins to widen and open too early, in the middle of pregnancy, without the signs of pain or labor)
- Lifestyle factors such as smoking, drinking alcohol, or using an illegal drugs
- Disorders of the immune system, including lupus
- Severe kidney disease
- Congenital heart disease
- Diabetes that is not controlled
- Thyroid disease
- Certain medications, such as the acne drug Accutane
- Severe malnutrition
In addition, women may be at increased risk for miscarriage as they get older. Studies show that the risks 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 the chromosomal abnormalities contributes to the age-related risk of miscarriage.
There’s no proof that stress or physical or sexual activity causes miscarriage.
Though any woman can miscarry, some are more likely to miscarry than others. Here are some of risk factors:
- Age: Older women are more likely to conceive a baby with a chromosomal abnormality and to miscarry as a result. In fact, 40-year-olds are about twice to miscarry as likely to 20-year-olds. Your risk of miscarriage may also rises with each child you bear.
- A history of miscarriages: Women who miscarriages two or more in a row are more likely than other women to miscarry again.
- Chronic diseases or disorders: A poorly controlled diabetes and certain inherited blood clotting disorders, autoimmune disorders (such as antiphospholipid syndrome or lupus), and hormonal disorders (such as polycystic ovary syndrome) are some of the conditions that could increase the risk of miscarriage.
- Uterine or cervical problems: Having certain congenital uterine abnormalities, a severe uterine adhesions (bands of scar tissue), or a weak or abnormally short cervix (known as cervical insufficiency) up the odds for a miscarriage. The link between uterine fibroids (a common, benign growth) and miscarriage is controversial, but most fibroids don’t cause problems.
- A genetic problem or history of birth defects: If you, your partner, or family members have a genetic abnormality, have had one identified in a previous pregnancy, or have given birth to a child with a birth defect, you’re at higher risk for miscarriage.
- Infections: Research shown a somewhat higher risk for miscarriage if you have listeria, mumps, rubella, measles, cytomegalovirus, parvovirus, gonorrhea, HIV, and certain other infections.
- Smoking, drinking, and using drugs: Smoking, drinking an alcohol, and using drugs like cocaine and MDMA (ecstasy) during pregnancy can all increase your risk for miscarriage. Some studies shows that an association between high levels of caffeine consumption and an increased risk of miscarriage.
- Medications: Some medications have been linked to increased risk of a miscarriage, so it’s important to ask your caregiver about the safety of any medications you are taking, even while you’re trying to conceive. This goes for a prescription and over-the-counter drugs, including a nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and aspirin.
- Environmental toxins: An environmental factors that might increase your risk include lead; arsenic; some chemicals, like formaldehyde, benzene, and ethylene oxide; and large doses of radiation or anesthetic gases.
- Paternal factors: Little is known about how the father’s condition contributes to a couple’s risk for a miscarriage, though the risk does rise with the father’s age. Researchers are studying for the extent to which sperm could be damaged by environmental toxins but still manage to fertilize an egg. Some studies have found that a greater risk of miscarriage when the father has been exposed to a mercury, lead, and some industrial chemicals and pesticides.
- Obesity: Some studies shows a link between obesity and miscarriage.
- Diagnostic procedures: There is a small increased risk of miscarriage after chorionic villus sampling and amniocentesis, which may performed for diagnostic genetic testing.
Your risk of miscarriaging is also higher if you get pregnant within three months after giving birth.
When a miscarriage occurs, the tissue passed from the vagina should be examined. This is done to determine if it was a normal placenta or a hydatidiform mole. It is also important to determine if whether any pregnancy tissue remains in the uterus.
If the pregnancy tissue does not naturally leave the body, the patient may be closely watched for up to 2 weeks. Surgery or medication (such as misoprostol) may be needed to remove the remaining contents from the womb.
After treatment, the woman usually resumes her normal menstrual cycle within 4 to 6 weeks. Any further vaginal bleeding should be carefully monitored. It’s often possible to become pregnant immediately. It is recommended that women will wait one normal menstrual cycle before trying to become pregnant again.
Exams and Tests
During a pelvic exam, your health care provider may see the cervix has opened (dilated) or thinned out (effacement).
Vaginal or abdominal ultrasound may be done to check the baby’s development, heart beat, and amount of bleeding.
The following blood tests may be performed:
- Blood type (if you have an Rh-negative blood type, you would require a treatment with Rh-immune globulin.)
- Complete blood count (CBC) to determine how much blood has been lost
- HCG (qualitative) to confirm pregnancy
- HCG (quantitative) done every several days or weeks
- WBC and differential to rule out infection
Complications of a complete miscarriage are rare.
An infected abortion may occur if any tissue from the placenta or fetus remains in the uterus after the miscarriage. Symptoms of an infection include fever, vaginal bleeding that does not stop, cramping, and a foul-smelling vaginal discharge. Infections can be serious and require immediate medical attention.
Women who lose a baby after 20 weeks of pregnancy receive different medical care. This is called premature delivery or fetal demise and requires immediate medical attention.
After a miscarriage, mothers and their partners may feel sad. This is normal. If your feelings of sadness do not go away or get worse, seek advice from family and friends as well as your health care provider.
How Long Will I Have to Wait Before I Can Try Again?
Discuss the timing of your next pregnancy with your health care provider. Some health care providers recommend waiting a certain amount of time (from one menstrual cycle to 3 months) before trying to conceive again. To prevent another miscarriage, your health care provider may recommend treatment with progesterone, a hormone needed for implantation in the uterus.
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. Pregnancy loss support groups may also be a valuable resource to you and your partner. Ask your health care provider for more information about these resources.