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Pregnancy and Miscarriage

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A miscarriage is the loss of a fetus before the 20th week of pregnancy. The medical term for a miscarriage is spontaneous abortion, but the condition is not an abortion in the common definition of the term.

According to the March of Dimes, as many as 50% of all pregnancies end in miscarriage -- most often before a woman misses a menstrual period or even knows she is pregnant. About 15% of recognized pregnancies will end in a miscarriage.

More than 80% of miscarriages occur within the first three months of pregnancy. Miscarriages are less likely to occur after 20 weeks gestation; these are termed late miscarriages.

What Are the Symptoms of a Miscarriage?

Symptoms of a miscarriage include:

  • Bleeding which progresses from light to heavy
  • Severe cramps
  • Abdominal pain
  • Fever
  • Weakness
  • Back pain

If you experience the symptoms listed above, contact your obstetric health care provider right away. He or she will tell you to come in to the office or go to the emergency room.

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 tiny structures inside the cells of the body which carry many genes. Genes determine all of a person's physical attributes, such as sex, hair and eye color, 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, including:

  • Infection
  • Exposure to 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 signs of pain or labor)
  • Lifestyle factors such as smoking, drinking alcohol, or using illegal drugs
  • Disorders of the immune system, including lupus
  • Severe kidney disease
  • Congenital heart disease
  • Diabetes that is not controlled
  • Thyroid disease
  • Radiation
  • 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 risk 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 chromosomal abnormalities contributes to the age-related risk of miscarriage.

There is no proof that stress or physical or sexual activity causes miscarriage.

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