Miscarriage Causes & Risks

Causes

Some miscarriages cannot be explained. Miscarriages often occur for the following reasons:

• Chromosomal abnormality (most common cause)
• Advanced maternal age
• Uterine defects
• Fibroids
• Scar tissue from a past surgery
• Insufficient progesterone (a female hormone needed to support pregnancy)
• Infection in the genital tract
• Immunologic factors that may cause blood-clotting problems or rejection of the fetus

Risk Factors

These factors increase your chance of having a miscarriage. Tell your doctor if you have any of these risk factors:

• Advancing maternal age
• Smoking
• Drinking alcohol at a level beyond two drinks per day
• Using illicit drugs (street drugs)
• Exposure to certain environmental toxins
• Infection, such as cytomegalovirus (CMV) and HIV
• Chronic maternal illness, eg, autoimmune diseases, such as lupus and insulin-dependent diabetes with uncontrolled blood sugar
• High-dose radiation therapy on the ovary and uterus or the pituitary gland during treatment for childhood cancer *¹

Having a miscarriage during your first pregnancy may place you at a higher risk for complications during your next pregnancy. *² These complications may include:

• Pre-eclampsia
• Threatened miscarriage
• Induced labor
• Preterm delivery
• Low birth weight
• Postpartum hemorrhage