1

2

3

Miscarriage Index

| Next page

• What is a miscarriage?
• What causes a miscarriage, and what are the tests for the different causes?
• What does NOT cause miscarriage?
• What are the symptoms of a miscarriage?
• What will the doctor look for during an examination with suspected miscarriage?
• How is threatened abortion evaluated?
• What are common terms a woman might hear during evaluation for miscarriage?
• What treatment can a woman expect when she has had a miscarriage?
• When should a woman receive evaluation for underlying causes of pregnancy loss?
• Can something be done to prevent future miscarriages?
• Miscarriage At A Glance

What is a miscarriage?

A miscarriage (spontaneous abortion) is any pregnancy that is non-viable (wherein the fetus cannot survive or is born before the 20th week of pregnancy). Miscarriages can be divided according to when in pregnancy they occur. Miscarriage occurs in about 15-20% of all recognized pregnancies, and usually occurs before the 13th week of pregnancy. Of those miscarriages before the eighth week, 30% have no fetus associated with the sac or placenta. This condition is called blighted ovum and many women are surprised to learn that there was never an embryo inside the sac.

Some miscarriages occur before women recognize that they are pregnant. About 15% of fertilized eggs are lost before the egg even has a chance to implant (embed itself) in the wall of the uterus. A woman would not generally identify this type of miscarriage. Another 15% of conceptions are lost before 8 weeks gestation. Once fetal heart function is detected in a given pregnancy, the chance of miscarriage is less than 5%.

A woman who may be showing the signs of a possible miscarriage (such as vaginal bleeding) may hear the term "threatened abortion" used to describe her situation.

What causes a miscarriage, and what are the tests for the different causes?

The most common causes of miscarriage in the first third of pregnancy (1st trimester) are chromosomal abnormalities, collagen vascular disease (such as lupus), diabetes, luteal phase defect, infection, and congenital (present at birth) abnormalities of the uterus. Each of these causes will be described below.

Chromosomes are microscopic components of every cell in the body that carry all of the genetic material that determine hair color, eye color and our overall appearance and makeup. These chromosomes duplicate themselves and divide many times during the process of development and there are numerous points along the way where a problem can occur. Certain genetic abnormalities are known to be more prevalent in couples that experience repeated losses. These genetic traits can be screened for by blood tests prior to attempting to become pregnant. Half of the fetal tissue from 1st trimester miscarriages contain abnormal chromosomes. This number drops to 20% with 2nd trimester miscarriages. In other words, abnormal chromosomes are more common with 1st trimester than with 2nd trimester miscarriages. First trimester miscarriages are so very common that unless they occur more than once, they are not considered "abnormal" per se. They do not prompt further evaluation unless they occur more than once. In contrast, 2nd trimester miscarriages are more unusual, and therefore may trigger evaluation even after a 1st occurrence. It is therefore clear that causes of miscarriages seem to vary according to trimester.

Collagen vascular diseases are illnesses in which a person's own immune system attacks their own organs. These diseases can be potentially very serious, either during or between pregnancies. In these diseases, a woman makes antibodies to her own body's tissues. Examples of collagen vascular diseases are systemic lupus erythematosus, and antiphospholipid antibody syndrome.

Diabetes generally can be well-managed during pregnancy, if a woman and her doctor work closely together. However, if the diabetes is insufficiently controlled, not only is the risk of miscarriages higher, but the baby can have major birth defects. Other problems can also occur in relation to diabetes during pregnancy. Good control of blood sugars during pregnancy is very important.

Luteal phase defect is a condition that can cause miscarriages because of an inadequate amount of progesterone hormone production during the menstrual cycle. The lack of progesterone may possibly make the inner lining of the womb (endometrium) unable to "support" a gestation (pregnancy), because progesterone is felt to be important in maintaining gestation until 10 weeks. Luteal phase defect is not well-understood. This lack of understanding probably contributes greatly to the controversy about how to diagnose and treat it. Sometimes medication treatment is prescribed to try to correct this lack of adequate progesterone. The specifics of whether and how luteal phase defect contributes to spontaneous miscarriage need to be determined, and effectiveness of commonly-used treatments require further research.

Infection of the uterus by bacteria and viruses has been associated with miscarriages. However, it is interesting to note that the same infections found at the time of miscarriage can also be present in normal pregnancies carried to completion. In fact, some of these bacteria, such as mycoplasma, are considered to be "normal" vaginal bacteria by many experts. Therefore, the exact role infection plays in miscarriages is uncertain. Sometimes antibiotics are given, especially to women who have had repeated abortions, if vaginal culture testing (on sampling of vaginal secretions) reveals mycoplasma.

1

2

3

Miscarriage Index

| Next page

Last Editorial Review: 4/15/02

Diseases & Conditions |  Symptoms & Signs |  Procedures & Tests |  Medications |  MedTerms Medical Dictionary 
Home |  Help |  Privacy |  About Us |  Search |  Focused Topics 
Site Map |  Advertise with Us |  Content Solutions