Abortions and breast cancer risk in premenopausal and postmenopausal women in Jiangsu Province of China.

To evaluate the relationship between abortions and risk of breast cancer, we conducted a case-control study with 669 cases and 682 population-based controls in Jiangsu Province of China. A structured questionnaire was used to elicit detailed information. Unconditional logistic regression analysis was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs).