Abortion and Breast Cancer Risk

The most up-to-date scientific research suggests that abortion does not influence a woman’s risk for breast cancer.

What is abortion?

An abortion happens when a pregnancy is ended before it reaches full term.

There are different types of abortion:

• Spontaneous abortion: The loss of a fetus before 5 months (20 weeks) into the pregnancy. Most people call this type of abortion a miscarriage. It is often caused by problems with the fetus or problems in the mother’s body.
• Stillborn birth (stillbirth): The death of a fetus after 5 months’ pregnancy. This death happens when the fetus is still in the uterus (womb).
• Induced abortion: A medical procedure done to end a pregnancy. It is what most people think of when they hear “abortion.”

Researchers have looked at how all types of abortion might affect a woman’s chance of getting breast cancer later in life.

Why has abortion been studied in connection with breast cancer?

The levels of certain hormones in a woman’s body can affect her risk for getting some types of breast cancer.

Hormone levels change during a woman’s lifetime, including during menstrual cycles and pregnancies. Hormone levels also change when an abortion occurs. This has led some researchers to study if abortion changes the risk of breast cancer, too.

Both breast cancer and abortion are also issues that can bring out strong feelings in people. Linking these topics has created a great deal of emotion and debate.

Research studies on abortion and breast cancer risk

Researchers around the world have studied whether abortion impacts breast cancer risk. Higher-quality studies have generally found no connection between abortion and breast cancer risk, but a few other studies have suggested a possible link between them.

This lack of agreement has led researchers to look at the total body of evidence to try to draw conclusions. For example, expert panels convened by the National Cancer Institute (NCI) and by the American College of Obstetricians and Gynecologists (ACOG) looked at the evidence and concluded that abortion is not related to an increased risk of breast cancer.

More recently, other researchers have re-evaluated the available data and generally reached the same conclusions. For example:

In a study published in 2020, researchers re-analyzed the data from all of the studies on abortion and breast cancer risk published up until 2018. They found that women who’ve experienced abortions did not have an increased risk of breast cancer. They also reported potential flaws in the studies that previously indicated abortion might increase the risk of breast cancer.

A 2018 report from the US National Academies of Sciences, Engineering, and Medicine concluded that abortion does not impact a woman’s risk for breast cancer.

Conclusion

Higher-quality studies have generally found no link between abortions and breast cancer risk. Researchers have also found flaws in previous studies that reported abortion may raise a woman’s risk for breast cancer. The best scientific evidence does not support a link between abortion and breast cancer risk.