American Cancer Society
“In February 2003, the US National Cancer Institute (NCI) convened a workshop of over 100 of the world’s leading experts who study pregnancy and breast cancer risk. The experts reviewed existing human and animal studies on the relationship between pregnancy and breast cancer risk, including studies of induced and spontaneous abortions. Among their conclusions were:
* Breast cancer risk is temporarily increased after a term pregnancy (resulting in the birth of a living child).
* Induced abortion is not associated with an increase in breast cancer risk.
* Recognized spontaneous abortion is not associated with an increase in breast cancer risk.
The level of scientific evidence for these conclusions was considered to be "well established" (the highest level).”
World Health Organization
“Most of the information on whether induced abortion modifies the risk of breast cancer among women comes from epidemiological studies, which are either case-control studies, or historical cohort studies. For information on abortion, all published case-control studies have relied on interviews of cases and controls with the inherent problem of recall bias. This bias occurs because women with breast cancer (cases) tend to truthfully report induced abortion while controls, who often are healthy women, have no "incentive" to provide information about personal and sensitive matters such as induced abortion. Such bias can produce elevated relative risk estimates in case-control studies. As a result, the outcome of such studies has been inconsistent, with some having indicated a small increase in risk, while others have not.
Historical cohort studies, on the other hand, are more methodologically sound. Two major studies have been carried out using this methodology, and neither found an increased risk of breast cancer associated with first trimester abortion.
Therefore, results from epidemiological studies are reassuring in that they show no consistent effect of first trimester induced abortion upon a woman’s risk of breast cancer later in life.”
National Cancer Institute
February 2003, the National Cancer Institute (NCI) convened a workshop of over 100 of the world’s leading experts who study pregnancy and breast cancer risk. Workshop participants reviewed existing population-based, clinical, and animal studies on the relationship between pregnancy and breast cancer risk, including studies of induced and spontaneous abortions. They concluded that having an abortion or miscarriage does not increase a woman’s subsequent risk of developing breast cancer. A summary of their findings, titled Summary Report: Early Reproductive Events and Breast Cancer Workshop, can be found at
Summary Report: Early Reproductive Events Workshop - National Cancer Institute .
American College of Obstetricians and Gynecologists
Washington, DC -- There is no evidence supporting a causal link between induced abortion and subsequent development of breast cancer, according to a committee opinion issued today by The American College of Obstetricians and Gynecologists (ACOG). ACOG's opinion is in agreement with the conclusion reached at the National Cancer Institute's Early Reproductive Events and Breast Cancer Workshop, which met in March 2003.
ACOG's review of the research on a link between abortion and later development of breast cancer concluded that studies on the issue were inconsistent and difficult to interpret, mainly due to study design flaws. Some studies showed either a significant decrease in breast cancer risk after abortion or found no effect. The most recent studies from China, the United Kingdom, and the US found no effect of induced abortion on breast cancer risk.