{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,3]],"date-time":"2026-10-03T18:44:45Z","timestamp":1791053085668,"version":"4.1.0"},"reference-count":86,"publisher":"BMJ","issue":"5","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Epidemiol Community Health"],"published-print":{"date-parts":[[1996,10]]},"abstract":"<jats:p>STUDY OBJECTIVE: To ascertain, from the published reports to date, whether or not a significantly increased risk of breast cancer is specifically attributable to a history of induced abortion, independent of spontaneous abortion and age at first full term pregnancy (or first live birth); to establish the relative magnitude of such risk increase as may be found, and to ascertain and quantify such risk increases as may pertain to particular subpopulations of women exposed to induced abortion; in particular, nulliparous women and parous women exposed before compared with after the first full term pregnancy. INCLUDED STUDIES: The meta-analysis includes all 28 published reports which include specific data on induced abortion and breast cancer incidence. Since some study data are presented in more than one report, the 28 reports were determined to constitute 23 independent studies. Overall induced abortion odds ratios and odds ratios for the different subpopulations were calculated using an average weighted according to the inverse of the variance. An overall unweighted average was also computed for comparison. No quality criteria were imposed, but a narrative review of all included studies is presented for the reader's use in assessing the quality of individual studies. EXCLUDED STUDIES: All 33 published reports including data on abortion and breast cancer incidence but either pertaining only to spontaneous abortion or to abortion without specification as to whether it was induced or spontaneous. These studies are listed for the reader's information. RESULTS: The overall odds ratio (for any induced abortion exposure; n = 21 studies) was 1.3 (95% confidence interval of 1.2, 1.4). For comparison, the unweighted overall odds ratio was 1.4 (1.3,1.6). The odds ratio for nulliparous women was 1.3 (1.0,1.6), that for abortion before the first term pregnancy in parous women was 1.5 (1.2,1.8), and that for abortion after the first term pregnancy was 1.3 (1.1,1.5). CONCLUSIONS: The results support the inclusion of induced abortion among significant independent risk factors for breast cancer, regardless of parity or timing of abortion relative to the first term pregnancy. Although the increase in risk was relatively low, the high incidence of both breast cancer and induced abortion suggest a substantial impact of thousands of excess cases per year currently, and a potentially much greater impact in the next century, as the first cohort of women exposed to legal induced abortion continues to age.<\/jats:p>","DOI":"10.1136\/jech.50.5.481","type":"journal-article","created":{"date-parts":[[2008,11,12]],"date-time":"2008-11-12T15:10:54Z","timestamp":1226502654000},"page":"481-496","source":"Crossref","is-referenced-by-count":90,"title":["Induced abortion as an independent risk factor for breast cancer: a comprehensive review and meta-analysis."],"prefix":"10.1136","volume":"50","author":[{"given":"J","family":"Brind","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"V M","family":"Chinchilli","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"W B","family":"Severs","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J","family":"Summy-Long","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[1996,10,1]]},"reference":[{"key":"ref_1","article-title":"In this study, the authors compared prospective, computerised data reported in their 1989 study58 with data on the same Swedish study population that had been gathered by retrospective interview for an earlier","volume-title":"study on oral contraceptives and breast cancer. As evidence of response bias, the authors reported a differential discordance between computer registry based data and interview based data, specifically, that an excess of cases relative to controls (7 versus 1, respectively) had \"over reported\" induced abortions, and that an excess of controls relative to cases (16 versus 5, respectively) had \"under reported\" induced abortions.79 From these discrepancies, the authors calculated that the OR for induced abortion based on the interview data (0.95) was significantly inflated compared with that based on the computer registry data (0.63; ratio of the","year":"1986","unstructured":"In this study, the authors compared prospective, computerised data reported in their 1989 study58 with data on the same Swedish study population that had been gathered by retrospective interview for an earlier (1986)80 study on oral contraceptives and breast cancer. As evidence of response bias, the authors reported a differential discordance between computer registry based data and interview based data, specifically, that an excess of cases relative to controls (7 versus 1, respectively) had \"over reported\" induced abortions, and that an excess of controls relative to cases (16 versus 5, respectively) had \"under reported\" induced abortions.79 From these discrepancies, the authors calculated that the OR for induced abortion based on the interview data (0.95) was significantly inflated compared with that based on the computer registry data (0.63; ratio of the"},{"key":"ref_2","first-page":"1","article-title":"An epidemiological study on cancer in Japan","volume":"48","author":"Segi, M.; Fukushima, I.; Fujisaku, S.","year":"1957","unstructured":"Segi M, Fukushima I, Fujisaku S, et al. An epidemiological study on cancer in Japan. 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