Understanding Miscarriage: Possible Causes

Miscarriage is common, but finding its cause may not be easy. If a cause can be found, it’s likely to be a problem with the baby or the uterus or cervix. Other factors cause miscarriage, but they're less common.

Problems with the baby

Either of these problems with the baby can cause a miscarriage:

• A problem with the baby’s chromosomes

• Birth defects

Problems with the uterus or cervix

Any of these problems with the uterus or cervix can cause a miscarriage:

• The uterus may be divided (have a septum). Or it may have growths, such as fibroids or adhesions.

• The lining of the uterus may be too thin for the fertilized egg to grow in.

• The cervix may be too weak to support the weight of a growing baby.

Other factors

Any of these problems can cause a miscarriage:

• Advanced maternal age (35 years or older)

• Having a previous miscarriage

• A serious maternal illness, such as uncontrolled diabetes, high blood pressure, or kidney disease

• A bad injury, such as from a car accident

• Contact with toxins or radiation

• Infections, such as syphilis

• Exposure to arsenic or lead

• Obesity

• Lifestyle factors including:

  • Drinking alcohol

  • Smoking cigarettes or using other tobacco, nicotine, or vaping products

What does not cause miscarriage?

A lot of myths and old wives’ tales try to explain the cause of miscarriage. But they aren't true. None of these causes miscarriage: