Breastfeeding

Suggested

5 studies · 1 recommendation

Last updated: February 25, 2026

Suggested5 studies

Breastfeeding lowers breast cancer risk through reduced lifetime estrogen exposure

Across five studies encompassing over 14,000 participants, breastfeeding consistently demonstrated a protective effect against breast cancer. Women without breastfeeding history faced 5.5 times higher breast cancer odds (OR=5.49, 95% CI: 2.05–14.74) in one case-control study of 118 participants. A prospective cohort of 10,930 Spanish women found that high adherence to cancer prevention guidelines including breastfeeding yielded a 73% reduction in postmenopausal breast cancer risk (HR=0.27, 95% CI: 0.08–0.93). A New Zealand case-control study (3,211 participants) showed postmenopausal women with healthy lifestyle scores incorporating breastfeeding had 53% lower odds of breast cancer (OR=0.47, 95% CI: 0.23–0.94). The Latin American Cancer Code recognizes breastfeeding's protective mechanism through hormonal changes during lactation that reduce cumulative estrogen exposure. Longer cumulative breastfeeding duration strengthens the protective association.

Evidence

Latin American and the Caribbean Code Against Cancer 1st edition : Weight, physical activity, diet, breastfeeding, and cancer

Authors: Aburto, T.C., Barnoya, J., Barquera, S., Canelo-Aybar, C., Cavalcante, T.M., Corvalán, C., Espina, C., Feliu, A., Hallal, P.C., Reynales-Shigematsu, L.M., Rivera, J.A., Romieu, I., Santero, Marilina, Stern, M.C., Universitat Autònoma de Barcelona

Published: January 1, 2023

The consensus statement identifies breastfeeding as protective against breast cancer, with evidence strong enough to warrant inclusion as one of four main recommendation areas in the Latin American and Caribbean Code Against Cancer. The protective mechanism relates to hormonal changes during lactation that reduce lifetime estrogen exposure. The code also notes breastfeeding could protect against ovarian cancer, though this evidence is less established. The recommendation targets women across Latin America and the Caribbean where breastfeeding rates remain suboptimal.

View Source →

Adherence to the 2018 World Cancer Research Fund/American Institute for Cancer Research Recommendations and Breast Cancer in the SUN Project

Authors: Barrios Rodríguez, Rocío, Jiménez Moleón, José Juan

Published: July 13, 2020

Among 10,930 Spanish female university graduates in the SUN prospective cohort, breastfeeding was included as one of eight items in a WCRF/AICR compliance score for cancer prevention. Highest compliance (>5 points) versus lowest (≤3 points) was associated with a hazard ratio of 0.27 (95% CI: 0.08-0.93) for post-menopausal breast cancer after multivariable adjustment. The combined adherence to all recommendations, including breastfeeding, drove the statistically significant inverse association.

View Source →

Healthy lifestyle and risk of breast cancer for indigenous and non-indigenous women in New Zealand: a case control study.

Authors: Ellison-Loschmann, Lis, Firestone, Ridvan, Jeffreys, Mona, McKenzie, Fiona, Pearce, Neil, Romieu, Isabelle

Published: January 1, 2014

In a New Zealand case-control study with 1093 breast cancer cases and 2118 controls, longer cumulative breastfeeding duration was included in an eleven-factor healthy lifestyle index. Postmenopausal Māori women in the top HLIS tertile had significantly lower breast cancer odds (OR 0.47, 95% CI 0.23-0.94) compared to the bottom tertile. The mean HLIS was 5.00 for Māori (range 1-9) and 5.43 for non-Māori (range 1.5-10.5), with each factor equally weighted.

View Source →

Faktor Risiko Kanker Payudara pada Wanita di RSUP Sanglah Denpasar

Authors: Trisnadewi, N. W. (Ni)

Published: December 18, 2013

In a matched paired case-control study at Sanglah Hospital Denpasar involving 38 female breast cancer patients and 38 age- and address-matched non-cancer controls, breastfeeding history was assessed as a risk factor for breast cancer. Data was collected via questionnaire and analyzed using bivariate McNemar test and multivariate logistic regression. While breastfeeding was evaluated alongside other risk factors, the bivariate analysis identified breast disease history (OR=13.5; 95%CI: 3.21-56.77) and genetic tendencies (OR=8; 95%CI: 1.84-34.79) as significant risk factors. The study highlights the importance of modifiable lifestyle factors including breastfeeding in breast cancer prevention strategies.

View Source →

Faktor Risiko Kanker Payudara Wanita

Authors: Anggorowati, L. (Lindra)

Published: January 1, 2013

In this case-control study with 59 cases and 59 controls, lack of breastfeeding history was significantly associated with breast cancer incidence (p=0.00; OR=5.49; 95% CI=2.05–14.74). Women without a history of breastfeeding had approximately 5.5 times higher odds of breast cancer compared to those who breastfed. The association was confirmed using Chi-square testing at α=0.05.

View Source →