title: Reproduction life history and hip fractures.
abstract: OBJECTIVE
  The present study assesses the association between reproduction and hip fractures.
  
  
  METHODS
  We used two surveys on elderly Danish twins of both sexes and the Danish National Register of Patients. In a cross-sectional study of 2045 twins aged 75-98 years in 1995, we studied the association between different aspects of reproduction and hip fractures leading to hospitalization between 1977 and 1994. In a prospective study, 3057 twins aged 66-99 years in 1977 were followed for a total of 29,112 years, and the association between number of children and incidence of hip fractures was investigated.
  
  
  RESULTS
  In the cross-sectional study, as well as the prospective study, we found, for both sexes, that having no children was associated with a higher risk of hip fracture compared to having at least one child. When excluding persons without children, we found no effect of number of birth events/children. In the cross-sectional study, we found no effect of birth interval length or age at first birth. For women, we found an effect of age at last birth.
  
  
  CONCLUSIONS
  No "cost-of-reproduction" in terms of hip fractures was observed. On the contrary, we found that having one or more children was associated with a lower risk of hip fracture.
authors: Danish Center for Demographic Research, Institute of Public Health, University of Southern Denmark, Odense C, Denmark.
authors: Hans Chr
authors: HC
authors: Petersen
authors: Bernard
authors: B
authors: Jeune
authors: James W
authors: JW
authors: Vaupel
authors: Kaare
authors: K
authors: Christensen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006620:Hip Fractures / Q000453:epidemiology*; D006801:Humans; D008297:Male; D010298:Parity; D011247:Pregnancy; D011446:Prospective Studies; D017584:Reproductive History; D012307:Risk Factors