Risk factors

Various factors increase the risk of miscarriage, including:

• Age. Women older than age 35 have a higher risk of miscarriage than do younger women. At age 35, you have about a 20 percent risk. At age 40, the risk is about 40 percent. And at age 45, it's about 80 percent.
• Previous miscarriages. Women who have had two or more consecutive miscarriages are at higher risk of miscarriage.
• Chronic conditions. Women who have a chronic condition, such as uncontrolled diabetes, have a higher risk of miscarriage.
• Uterine or cervical problems. Certain uterine conditions or weak cervical tissues (incompetent cervix) might increase the risk of miscarriage.
• Smoking, alcohol and illicit drugs. Women who smoke during pregnancy have a greater risk of miscarriage than do nonsmokers. Heavy alcohol use and illicit drug use also increase the risk of miscarriage.
• Weight. Being underweight or being overweight has been linked with an increased risk of miscarriage.
• Invasive prenatal tests. Some invasive prenatal genetic tests, such as chorionic villus sampling and amniocentesis, carry a slight risk of miscarriage.