title: Does having children extend life span? A genealogical study of parity and longevity in the Amish.
abstract: BACKGROUND
  The relationship between parity and life span is uncertain, with evidence of both positive and negative relationships being reported previously. We evaluated this issue by using genealogical data from an Old Order Amish community in Lancaster, Pennsylvania, a population characterized by large nuclear families, homogeneous lifestyle, and extensive genealogical records.
  
  
  METHODS
  The analysis was restricted to the set of 2,015 individuals who had children, were born between 1749 and 1912, and survived until at least age 50 years. Pedigree structures and birth and death dates were extracted from Amish genealogies, and the relationship between parity and longevity was examined using a variance component framework.
  
  
  RESULTS
  Life span of fathers increased in linear fashion with increasing number of children (0.23 years per additional child; p =.01), while life span of mothers increased linearly up to 14 children (0.32 years per additional child; p =.004) but decreased with each additional child beyond 14 (p =.0004). Among women, but not men, a later age at last birth was associated with longer life span (p =.001). Adjusting for age at last birth obliterated the correlation between maternal life span and number of children, except among mothers with ultrahigh (>14 children) parity.
  
  
  CONCLUSIONS
  We conclude that high parity among men and later menopause among women may be markers for increased life span. Understanding the biological and/or social factors mediating these relationships may provide insights into mechanisms underlying successful aging.
authors.affiliation: Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Patrick F
authors.initials: PF
authors.lastname: McArdle
authors.forename: Toni I
authors.initials: TI
authors.lastname: Pollin
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: O'Connell
authors.forename: John D
authors.initials: JD
authors.lastname: Sorkin
authors.forename: Richa
authors.initials: R
authors.lastname: Agarwala
authors.forename: Alejandro A
authors.initials: AA
authors.lastname: Schäffer
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Streeten
authors.forename: Terri M
authors.initials: TM
authors.lastname: King
authors.forename: Alan R
authors.initials: AR
authors.lastname: Shuldiner
authors.forename: Braxton D
authors.initials: BD
authors.lastname: Mitchell
mesh_terms: D000368:Aged; D005220:Fathers; D005260:Female; D006801:Humans; D008136:Longevity; D008297:Male; D009035:Mothers; D010298:Parity; D010375:Pedigree; D010414:Pennsylvania; D011247:Pregnancy