title: Birth weight, breast cancer and the potential mediating hormonal environment.
abstract: BACKGROUND
  Previous studies have shown that woman's risk of breast cancer in later life is associated with her infants birth weights. The objective of this study was to determine if this association is independent of breast cancer risk factors, mother's own birth weight and to evaluate association between infants birth weight and hormonal environment during pregnancy. Independent association would have implications for understanding the mechanism, but also for prediction and prevention of breast cancer.
  
  
  RESULTS
  Risk of breast cancer in relation to a first infant's birth weight, mother's own birth weight and breast cancer risk factors were evaluated in a prospective cohort of 410 women in the Framingham Study. Serum concentrations of estriol (E3), anti-estrogen alpha-fetoprotein (AFP), and pregnancy-associated plasma protein-A (PAPP-A) were measured in 23,824 pregnant women from a separate prospective cohort, the FASTER trial. During follow-up (median, 14 years) 31 women (7.6%) were diagnosed with breast cancer. Women with large birth weight infants (in the top quintile) had a higher breast cancer risk compared to other women (hazard ratio (HR), 2.5; 95% confidence interval (CI), 1.2-5.2; P = 0.012). The finding was not affected by adjustment for birth weight of the mother and traditional breast cancer risk factors (adjusted HR, 2.5; 95% CI, 1.2-5.6; P = 0.021). An infant's birth weight had a strong positive relationship with the mother's serum E3/AFP ratio and PAPP-A concentration during pregnancy. Adjustment for breast cancer risk factors did not have a material effect on these relationships.
  
  
  CONCLUSIONS
  Giving birth to an infant with high birth weight was associated with increased breast cancer risk in later life, independently of mother's own birth weight and breast cancer risk factors and was also associated with a hormonal environment during pregnancy favoring future breast cancer development and progression.
authors: Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas, United States of America. rkbukows@utmb.edu
authors: Radek
authors: R
authors: Bukowski
authors: Rowan T
authors: RT
authors: Chlebowski
authors: Inger
authors: I
authors: Thune
authors: Anne-Sofie
authors: AS
authors: Furberg
authors: Gary D V
authors: GD
authors: Hankins
authors: Fergal D
authors: FD
authors: Malone
authors: Mary E
authors: ME
authors: D'Alton
mesh_terms: D001724:Birth Weight; D001943:Breast Neoplasms / Q000097:blood* / Q000453:epidemiology*; D015331:Cohort Studies; D004964:Estriol / Q000097:blood; D005260:Female; D006728:Hormones / Q000097:blood*; D006801:Humans; D007223:Infant; D008875:Middle Aged; D009035:Mothers / Q000706:statistics & numerical data; D011247:Pregnancy; D011266:Pregnancy-Associated Plasma Protein-A / Q000378:metabolism; D012307:Risk Factors; D000509:alpha-Fetoproteins / Q000378:metabolism
chemical_list: D006728:Hormones; D000509:alpha-Fetoproteins; D011266:Pregnancy-Associated Plasma Protein-A; D004964:Estriol