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Induced abortion causes breast cancer

What you may have heard

Women who undergo induced medical abortions have a higher risk of developing cancer.

What science tells us

Hormone levels change dramatically during pregnancy and decrease a woman’s number of menstrual cycles, which affects breast cancer risk (ACS). Abortion is believed to interrupt the normal cycle of hormones during pregnancy. There are multiple types of abortion, and each has a slightly different relationship with cancer risk. Induced abortion is a medical procedure performed to end a pregnancy. 

Epidemiological Evidence

The most reliable study on this subject was done in the 1990s, and researchers found that induced abortions had no overall effect on the risk of breast cancer (ACS, ACOG). This association was confirmed in at least six other large studies across the world. Spontaneous abortion, or miscarriage, is the loss of a fetus before five months (20 weeks) into the pregnancy. There has also been no relationship found between spontaneous abortion and breast cancer risk. Risk of breast cancer is lower in women who have a full-term pregnancy before the age of 30, and the risk of breast cancer decreases with the number of full-term pregnancies.

Laboratory Evidence/Supporting Evidence

There is no laboratory evidence that induced (medical) abortions causes an increased risk of cancer.

How to reduce your risk

There are many known risk factors for breast cancer. Drinking alcohol is clearly linked to an increased risk of breast cancer, and risk increases with the amount of alcohol consumed. Women who have one alcoholic drink a day have a small (7-10%) increase compared with non-drinkers. This risk increases to 20% in women who have 2-3 drinks a day (ACS).

Another risk factor is being overweight or obese. Especially after a woman reaches menopause, most of a woman’s estrogen comes from fat tissue. Excess fat can raise estrogen levels and increase your risk of developing breast cancer. Women who are overweight or obese also tend to have higher insulin levels, which are associated with some cancers (ACS). Both of these risk factors may be offset with 150-300 minutes of physical activity and a healthy diet, which reduces your risk of breast cancer (ACS).

Bottom line

Neither induced (medical) nor spontaneous abortions appear to increase breast cancer risk.

American Cancer Society (ACS): Lifestyle-related breast cancer risk factors
ACS: Breast cancer risk factors you cannot change
ACS: Abortion and breast cancer
American College of Obstetricians and Gynecologists (ACOG): Abortion and cancer risk


Published: June 30, 2021
Verified/updated: August 22, 2022