Document Detail

Age at first birth and breast cancer risk.
MedLine Citation:
PMID:  5312521     Owner:  NLM     Status:  MEDLINE    
An international collaborative study of breast cancer and reproductive experience has been carried out in 7 areas of the world. In all areas studied, a striking relation between age at first birth and breast cancer risk was observed. It is estimated that women having their first child when aged under 18 years have only about one-third the breast cancer risk of those whose first birth is delayed until the age of 35 years or more. Births after the first, even if they occur at an early age, have no, or very little, protective effect. The reduced risk of breast cancer in women having their first child at an early age explains the previously observed inverse relationship between total parity and breast cancer risk, since women having their first birth early tend to become ultimately of high parity. The association with age at first birth requires different kinds of etiological hypotheses from those that have been invoked in the past to explain the association between breast cancer risk and reproductive experience.
B MacMahon; P Cole; T M Lin; C R Lowe; A P Mirra; B Ravnihar; E J Salber; V G Valaoras; S Yuasa
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Bulletin of the World Health Organization     Volume:  43     ISSN:  0042-9686     ISO Abbreviation:  Bull. World Health Organ.     Publication Date:  1970  
Date Detail:
Created Date:  1971-02-02     Completed Date:  1971-02-02     Revised Date:  2010-10-26    
Medline Journal Info:
Nlm Unique ID:  7507052     Medline TA:  Bull World Health Organ     Country:  SWITZERLAND    
Other Details:
Languages:  eng     Pagination:  209-21     Citation Subset:  IM    
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MeSH Terms
Age Factors
Breast Neoplasms / epidemiology,  etiology*
Epidemiologic Methods
Maternal Age*
Socioeconomic Factors

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