The short-term and long-term effect of a pregnancy on breast cancer risk: a prospective study of 802,457 parous norwegian women

ABSTRACT Time-related effects of a pregnancy on breast cancer risk were examined in a population-based prospective study of 802,457 parous Norwegian women aged 20-56 years. The mean

follow-up time was 16.4 years. A total of 4787 women were diagnosed with breast cancer. We observed a short-term increase in risk of breast cancer after a full-term pregnancy, with a maximum

3-4 years after delivery, followed by a long-lasting decrease in risk. The maximum risk was about twice the risk for women whose last delivery was 20 or more years previously (incidence

rate ratio = 1.99, 95% confidence interval = 1.70-2.33). Compared with nulliparous women, those with one or two children were at higher risk in the first decade after the last pregnancy,

whereas those with three or more children were at lower risk in most categories of time since the last birth. The positive association between breast cancer risk and age at last birth was

markedly reduced after adjustment for time since last birth. We conclude that there is a non-linear relationship between breast cancer incidence and time since last birth. Part of the

relation with age at last birth may be attributed to the association with time since last birth. Access through your institution Buy or subscribe This is a preview of subscription content,

access via your institution ACCESS OPTIONS Access through your institution Subscribe to this journal Receive 24 print issues and online access $259.00 per year only $10.79 per issue Learn

more Buy this article * Purchase on SpringerLink * Instant access to full article PDF Buy now Prices may be subject to local taxes which are calculated during checkout ADDITIONAL ACCESS

OPTIONS: * Log in * Learn about institutional subscriptions * Read our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS A CASE-CONTROL STUDY TO EVALUATE THE IMPACT OF

THE BREAST SCREENING PROGRAMME ON MORTALITY IN ENGLAND Article Open access 23 November 2020 THE GLOBAL BURDEN OF BREAST CANCER AMONG WOMEN OF REPRODUCTIVE AGE: A COMPREHENSIVE ANALYSIS

Article Open access 18 March 2025 A SYSTEMATIC REVIEW OF DETERMINANTS OF BREAST CANCER RISK AMONG WOMEN WITH BENIGN BREAST DISEASE Article Open access 15 February 2025 AUTHOR INFORMATION

AUTHORS AND AFFILIATIONS * Department of Epidemiology, University of Bergen, Norway G Albrektsen Authors * G Albrektsen View author publications You can also search for this author inPubMed 

Google Scholar * I Heuch View author publications You can also search for this author inPubMed Google Scholar * G Kvåle View author publications You can also search for this author inPubMed 

Google Scholar RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Albrektsen, G., Heuch, I. & Kvåle, G. The short-term and long-term effect of a

pregnancy on breast cancer risk: a prospective study of 802,457 parous Norwegian women. _Br J Cancer_ 72, 480–484 (1995). https://doi.org/10.1038/bjc.1995.359 Download citation * Issue Date:

01 August 1995 * DOI: https://doi.org/10.1038/bjc.1995.359 SHARE THIS ARTICLE Anyone you share the following link with will be able to read this content: Get shareable link Sorry, a

shareable link is not currently available for this article. Copy to clipboard Provided by the Springer Nature SharedIt content-sharing initiative