Spontaneous Abortion Causes, Signs and Myths

Woman disappointed by a spontaneous abortion

"Spontaneous abortion" is the term doctors use for a miscarriage that happens in the first 20 weeks of pregnancy. Miscarriages happen in about 10-20 percent of known pregnancies, and it's not uncommon to have more than one. Some miscarriages happen before the woman even realizes she's pregnant. Having a miscarriage does not necessarily mean a woman cannot have a normal pregnancy.

Although the word "abortion" also refers to intentional termination of a pregnancy, a spontaneous abortion is different. Most of the time, there is nothing the woman could have done to prevent it.

What Causes Spontaneous Abortions?

Many spontaneous abortions happen because something was wrong with the baby. A developing baby is the result of a very complex process involving genetic messages, cell development, and rapid growth. Amazingly, most of the time everything works correctly. But, if something goes wrong, the baby may not develop properly.

Spontaneous abortions are most commonly caused by a problem with the baby's genetic material. Each cell in a developing baby's body contains genes from both the mother and the father. The baby's cells divide and grow to make more cells, which combine to make all the parts of the baby. Sometimes, a cell accidentally gets an extra copy of one parent's genes, or doesn't get a complete set. When that cell divides, its offspring won't work properly, and the baby won't develop normally. This kind of problem is usually just an accident: there's no reason the next baby won't grow and develop just fine.

Health Problems in the Mother

Sometimes, a health problem in the mother is the cause of a spontaneous abortion. For example, if the mother has severe diabetes, immune system problems, or a tendency to develop blood clots, she is at increased risk for miscarriage. Older women are more likely to have miscarriages than younger women, even if they're healthy.

Some lifestyle habits can increase the risk of miscarriage. These include:

  • Smoking
  • Drinking alcohol
  • Using illegal drugs
  • Heavy caffeine intake

Some infections can lead to miscarriage. For example, pregnant women should avoid any possibility of contracting a sexually transmitted disease. Women who are not already immune should also avoid contact with anyone who has German measles, also called rubella.

Problems with the Uterus

Some spontaneous abortions happen because of a problem with the mother's uterus. If it is not shaped properly, it may not be able to support a developing baby. Another possible cause is cervical incompetence. The cervix, located high up in the vagina, is the entrance to the uterus. Normally, the cervix stays tightly closed until it's time to give birth. If it does not stay closed, the baby can begin to slip out long before it's time to be born, resulting in a miscarriage.

Signs of a Miscarriage

Common signs and symptoms of miscarriage include:

  • Vaginal bleeding
  • Abdominal cramps and/or pain in the lower back
  • Passage of blood clots or tissue from the vagina
  • Loss of pregnancy symptoms

If any of these things happen during your pregnancy, you should contact your health care provider right away.

Myths About Miscarriage

Often, a woman who has lost a pregnancy will feel guilty, wondering if the miscarriage was her fault.

Here are some things that do not cause miscarriages:

  • Healthy levels of exercise
  • Having sex
  • Falling or hitting your stomach, unless you are severely injured
  • Lifting heavy objects
  • Continuing to work during the pregnancy, as long as your job doesn't involve hazards like dangerous chemicals


There is no way to prevent spontaneous abortions which happen because of genetic problems in the baby. These babies would not survive even if the pregnancy continued.

For miscarriages caused by health problems in the mother, the best prevention is to get good prenatal care and stay as healthy as possible. If you have a chronic illness like diabetes, see your doctor to get your condition under control before you start trying to conceive.

Taking folic acid, starting before you become pregnant, will help prevent a serious birth defect that can lead to miscarriage. You should also eat healthy, stay in shape, and avoid exposure to risks like cigarette smoke, alcohol, and infections.

If You've Lost a Pregnancy

Having a miscarriage can be very stressful and sad. It's important to acknowledge your feelings. If you can, talk to your partner, your family, and supportive friends. It's also ok to talk with your doctor and even to seek professional counseling.

Ask your doctor to explain exactly what he/she thinks was the cause of your miscarriage. If you have a chronic medical problem, if you or your partner has a known genetic disorder, or if you've had two or more miscarriages, you may need special treatment, or even genetic counseling to see if you should try again. Otherwise, your doctor will probably reassure you. Most women who have had a spontaneous abortion can go on to have a normal pregnancy.

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Spontaneous Abortion Causes, Signs and Myths