A new study from Finland has found no connection between abortion or miscarriage and the risk of developing breast cancer, providing strong evidence to clarify a topic that often leads to public confusion. The research involved a large case–control study using nationwide registry data. Scientists examined information from over 31,000 women diagnosed with breast cancer spanning nearly fifty years, along with more than 158,000 matched controls from the general population.
Unlike many earlier studies that relied on self-reported pregnancy histories, this analysis drew data from mandatory national registries. These records have tracked induced abortions since 1950 and miscarriages treated by doctors since 1969. The researchers also accounted for socioeconomic status, physical activity related to jobs, and hormone therapy use among older women in their statistical analyses.
The results showed that women younger than 50 who had experienced an induced abortion had the same risk for breast cancer as those without such a history. For women aged 50 or older, the risk was slightly lower, but not significantly. The study also carefully looked at miscarriage history and found no link to breast cancer risk in either age group. Additionally, there was no change in risk based on the number of abortions or miscarriages, or the age at which these events first happened.
One subgroup appeared to show a minor increase in postmenopausal breast cancer risk for women whose first abortion occurred before the age of 20. However, experts warned this could simply be due to chance, especially since the interval between abortion and cancer diagnosis stretched over 30 years. Meanwhile, other known risk factors behaved as expected: earlier age at first childbirth lowered the risk for premenopausal breast cancer, and hormone therapy – especially long-term estrogen and progestin use – raised breast cancer risk in postmenopausal women.
The researchers highlighted that misinformation about abortion and breast cancer risk is still present, including in some US state counseling materials. They stressed that their results are consistent with previous large-scale studies and show no evidence for a link. The findings are likely to help improve clinical counseling and offer reassurance to women concerned about these risks. No competing interests were declared for this study.
