Niloofar Behin - B.Sc. student of Midwifery, a member of the student research committee, Islamic Azad University, Khorasgan Branch, Esfahan, Iran
Fatemeh Sohran - M.Sc. of Consultation on Midwifery, midwifery trainer at Faculty of Nursing and Midwifery, Islamic Azad University, Khorasgan Branch, Esfahan, Iran

Introduction: Breast cancer is the commonest type of cancer in the world which has taken its toll on women. The great number of hormonal changes that occur during pregnancy play a critical role in the emergence of the risks of breast cancer; therefore, the present study has been designed to investigate the effects of pregnancy-related variables on the risks of breast cancer.Methods: The present study which is a systematic review article has searched for keywords like pregnancy, breast cancer, abortion, and pre-eclampsia in the following international databases: Sid, PubMed, Scopus, Magiran, Google Scholar, Web of Science, and Science Direct. Sixty articles were extracted and after examining the entry and exit criteria based on Prisma Checklist, 10 of the articles were removed and finally, 50 of the selected articles from 2000 to 2017 reached the criteria and data were extracted from them.Results: The findings of the study revealed that having abortion records increased the risks of breast cancer. Furthermore, a history of pre-eclampsia had a protective role in breast cancer. There is a need for further studies to be conducted on the potential relationship between multiple birth, gestational diabetes, and breast cancer.conclution: The results suggest that abortion and pre-eclampsia have a stronger relationship with breast cancer.

pregnancy, breast cancer, abortion, pre-eclampsia