Risk Factors of a Miscarriage

Also referred to as a spontaneous abortion, a miscarriage is defined as the sudden loss of a fetus during the early stages of pregnancy—usually before the 20th week. According to the American Pregnancy Association, approximately 10% to 25% of all clinically confirmed pregnancies will end in miscarriage.

The causes of miscarriage are usually completely out of the mother’s control. Miscarriages are usually caused by abnormalities in the genes or chromosomes, but sometimes the cause is unknown.

Risk Factors

Most miscarriages are due to natural, unpreventable causes. However, there are certain factors that can increase your risk for having a miscarriage. These include:

  • Age: Women who are younger than 35 have the lowest risk of miscarriage, at about 15%. However, as you get older, your risk of miscarriage will increase. At age 35, your risk will increase to 20%, and at age 40 the risk is about 40%. After the age of 45, your risk increases to almost 80%. The age of the father may also play a role, as there are some studies that suggest women who become pregnant by older men will be at a slightly higher risk of miscarriage than normal.
  • Weight: Being underweight or overweight has been linked to an increased risk of miscarriage.
  • Chronic conditions: There are a few cases in which the health of the mother may contribute to the risk of miscarriage. Some examples of health conditions that can increase your risk include uncontrolled diabetes, infections, hormonal problems, thyroid disease, and uterus or cervix problems.
  • Smoking, alcohol, or drug use: If you smoke during your pregnancy, you will have a higher risk than women who are nonsmokers. Additionally, if you drink alcohol heavily or use drugs, your risk of miscarriage will also be significantly increased.
  • Previous miscarriages: If you have experienced two or more consecutive miscarriages, you will be at a slightly increased risk of having another miscarriage. This is referred to as recurrent miscarriages.
  • Invasive prenatal tests: There are some prenatal tests that carry a slight risk of miscarriage. Some examples include chorionic villus sampling and amniocentesis.
  • Uterine or cervical problems: If you have any abnormalities or weak cervical tissue, this will also increase your risk of miscarriage.


Most of the time, there is not much you can do to prevent a miscarriage from occurring. There are some risk factors that are out of your control, such as age, chronic conditions, or uterine and cervical problems. However, there are some risk factors that you can control, such as keeping yourself healthy and avoiding smoking and alcohol. If you do have any chronic conditions that increase your risk, you can work with your doctor to keep the condition under control and lower your risk as much as possible.

Open communication with your doctor is the most important thing you can do when you are pregnant to prevent any problems or complications from occurring. 

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Posted on May 5, 2023