Story perspectives

Pregnancy and Breastfeeding Slash Long-Term Breast Cancer Risk

10/30/2025

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Summary

Story summary

Pregnancy and breastfeeding significantly lower a woman's long-term breast cancer risk, especially triple-negative cancer, according to research led by Professor Sherene Loi.
The study, published in Nature, shows pregnancy and breastfeeding increase CD8+ T cells in breast tissue that persist for years.
Each pregnancy reduces risk by about 7%.
Five months of breastfeeding lowers risk by about 2%.
Delaying childbirth may contribute to rising breast cancer rates.

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Story summary

Pregnancy and breastfeeding significantly lower a woman's long-term breast cancer risk, especially triple-negative cancer, according to research led by Professor Sherene Loi.
The study, published in Nature, shows pregnancy and breastfeeding increase CD8+ T cells in breast tissue that persist for years.
Each pregnancy reduces risk by about 7%.
Five months of breastfeeding lowers risk by about 2%.
Delaying childbirth may contribute to rising breast cancer rates.