Back to today’s briefing

Story perspectives

Early Birth Increases Breast Cancer Risk, Study Finds

10/3/2025

37 9 Full Breakdown

Summary

Story summary

A Mendelian randomization study links reproductive factors, age at first birth, to breast cancer risk across ER-negative and ER-positive subtypes.
Earlier age at first birth may raise overall risk, particularly for ER-negative cancers.
The Tyrer-Cuzick Breast Cancer Risk Calculator is free on She MD’s website.
Limitations include weak genetic instruments and biases from self-reported data; larger, diverse studies are needed.

1 of 1

Story summary

A Mendelian randomization study links reproductive factors, age at first birth, to breast cancer risk across ER-negative and ER-positive subtypes.
Earlier age at first birth may raise overall risk, particularly for ER-negative cancers.
The Tyrer-Cuzick Breast Cancer Risk Calculator is free on She MD’s website.
Limitations include weak genetic instruments and biases from self-reported data; larger, diverse studies are needed.