Study Confirms that Abortion and Miscarriage Not Linked to Breast Cancer Risk

Monday, July 26 2010

A study published in the March 27, 2004 issue of The Lancet concludes that pregnancies ending in miscarriage or induced abortion do not increase a woman's chance of developing breast cancer.

The researchers re-analyzed data from 53 different epidemiological studies conducted in 16 countries, which involved a total of 83,000 women with breast cancer. The data were analyzed in two groups according to the design of the study, with one group of prospective studies in which the participants were asked about their abortion and miscarriage history before being diagnosed with breast cancer. The second group of data came from retrospective studies in which women were asked for abortion and miscarriage information after their cancer diagnoses.

Researchers calculated the relative risk of developing breast cancer for the two groups compared to the risk for a woman who has no history of abortion or miscarriage - a relative risk of 1.0 or less demonstrates no adverse effect on subsequent breast cancer risk. They reported that the overall relative risk of breast cancer was 0.93 among women in the prospective studies group who had undergone at least one abortion and 0.98 among women who had had at least one miscarriage, indicating no increased risk of breast cancer after miscarriage or abortion. They also found that the number or timing of abortions or miscarriages did not alter breast cancer risk among women in the prospective studies group.

According to the lead researcher, Dr. Valerie Beral, this study represents the first time that original data from similar studies has been grouped and analyzed together in a similar way, allowing for a definitive conclusion that "neither induced abortions nor miscarriages increase breast cancer risk," and that previous studies claiming such a link used "unreliable data and poorly conducted research."

Source: Kaiser Daily Reproductive Health Report, 26/03/2004,

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