The incidence and mortality rates of breast cancer in Northeast Brazil are increasing and little is known about prevailing reproductive factors contributing to this increase. A case-control study was conducted in a public hospital of Campina Grande, state of Paraiba, including 81 women with diagnosed invasive breast cancer and 162 age matched (±5 years) controls. Binominal logistic regression analysis was applied to estimate odds ratio (OR) and confidence intervals (CI) of risk factors. In this model, age at menarche≤12 (OR=2.120; CI: 1.043-4.308; p=0.038), single parity (OR=3.748; CI: 1.459- 9.627; p=0.06) and reproductive period>10 years (OR=3.042; CI: 1.421- 6.512; p=0.04) were identified as independent variables that significantly increased breast cancer risk of parous women. Compared to parous women who never practised breastfeeding, total breastfeeding time>24 months decreased the risk of breast cancer (OR=0.258; CI: 0.084- 0.787; p=0.017). The results indicated that modifiable reproductive factors contribute to breast cancer risk in women included in the present study. Women's knowledge about factors such as the protective effect of breastfeeding could reduce the risk of breast cancer.