Breastfeeding May Decrease the Risk of Ovarian Cancer

     Ovarian cancer is a malignant growth arising from the ovary.   In the US almost 20,000 cases of ovarian cancer were reported in 2006.  Symptoms may include: bloating, pelvic pain, abdominal pressure, abdominal fullness, swelling, persistent indigestion, change in bowel habits such as constipation, change in bladder habits such as frequent need to urinate, increased abdominal girth and low back pain.

          More than 90% of ovarian cancers arise from epithelium of ovary. An older study has suggested that breastfeeding may decrease the risk of epithelial ovarian cancer.[1] In this study,  the researchers collected data from participants in a population-based design in western Washington State, USA, who had had at least one birth. It included 881 cases and 1345 controls to assess the correlation  between breastfeeding and ovarian cancer.

     Women who breastfed had a 22% reduction in the risk of ovarian cancer compared with those who had never breastfed (OR = 0.78, 95% CI 0.64–0.96) and risk reduction appeared greatest with longer durations of feeding per child (OR = 0.56, 95% CI 0.32–0.98 for 18 months average duration breastfeeding versus none).

     Introduction of supplementary feeds did not alter these effects. The overall risk reduction appeared greatest for the endometrioid and clear-cell subtypes of the epithelial ovarian cancer (OR per month of average breastfeeding per child breastfed = 0.944, 95% CI 0.903–0.987).

     According to this study, the possible mechanism by which breastfeeding decreased risk of ovarian cancer was that breastfeeding suppresses gonadotropin hormones which subsequently decreases estrogen levels and causes anovulation which leads to lactational amenorrhea. Estrogens are known causes of ovarian cancers. Therefore by decreasing estrogen levels, breastfeeding apparently protects against ovarian cancers.

     Thus, this study suggests that women who breastfeed may have a decreased risk of ovarian cancer. Limitations of study include that all the information was recalled by the women who participated in this study, often from many years in the past. Thus recall bias may alter some of the findings in this study. Nevertheless, this data  strongly suggests a relationship between breastfeeding and a reduced risk of ovarian cancer.

Sonia Shoukat  M.D.

Thomas W. Hale Ph.D.


1) S. J. Jordan, K. L. Cushing-Haugen, K. G. Wicklund, J. A. Doherty, M. A. Rossing. Breast-feeding and risk of epithelial ovarian cancer. Cancer Causes Control (2012) 23:919–927.