Miscarriage

Symptoms

Symptoms of a miscarriage include:

• Vaginal bleeding that may be light or heavy, constant or irregular. Although bleeding is often the first sign of a miscarriage, first-trimester bleeding may also occur with a normal pregnancy. But bleeding with pain is a sign that miscarriage is more likely.
• Pain. You may have pelvic cramps, abdominal pain, or a persistent, dull ache in your lower back. Pain may start a few hours to several days after bleeding has begun.
• Blood clots or greyish (fetal) tissue passing from the vagina.

It is not always easy to tell whether a miscarriage is taking place. A miscarriage often does not occur as a single event but as a chain of events over several days. One woman's physical experience of a miscarriage can be very different from another woman's experience.

Risk factors for miscarriage

Factors that may increase your risk of miscarriage include:

• Your age, especially at age 35 and older.
• A history of recurrent miscarriage (three or more).
• A history of miscarriages on your mother's side of the family.
• Polycystic ovary syndrome, which can cause ovulation problems, obesity, increased male hormone levels, and an increased risk of diabetes.
• A poorly controlled ongoing disease (such as diabetes or an autoimmune disease).
• Certain bacterial or viral infections during pregnancy.
• A blood-clotting disorder such as antiphospholipid antibody syndrome.
• Problems with the structure of the uterus (such as a T-shaped uterus).
• A history of pregnancy with a birth defect.
• A physical injury.
• Exposure to dangerous chemicals, such as benzene, arsenic, or formaldehyde, before or during pregnancy.
• The father's age, especially beyond age 35.²

Other factors that may slightly raise miscarriage risk include:

• Non-steroidal anti-inflammatory drug (NSAID) use (such as ibuprofen or naproxen) at the time of conception or during early pregnancy.³
• Alcohol use during pregnancy.⁴
• Cigarette smoking during pregnancy.⁵
• Cocaine use during pregnancy.⁵
• A snakebite.⁶
• Heavy caffeine use during pregnancy.
• A chorionic villus sampling (CVS) or amniocentesis to test for birth defects or genetic problems. When done by a highly trained provider, one study showed that these tests have about a 1 in 400 risk of miscarriage.⁷ Some studies have shown higher risks, between 2 and 4 in 400.⁸ This greater risk may be more likely in centres with less experienced providers, especially for CVS.

There are also known factors that do not increase the risk of miscarriage, such as exposure to computer monitors or electric blankets, sexual intercourse, and exercise.

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Author:	Kathe Gallagher, MSW Carrie Henley	Last Updated: June 28, 2007
Medical Review:	Joy Melnikow, MD, MPH - Family Medicine Deborah A. Penava, BA, MD, FRCSC, MPH - Obstetrics and Gynecology
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