title: Effect of lactation on postmenopausal bone mineral density of the lumbar spine.
abstract: OBJECTIVE
  To investigate the relationship between lactation and bone mineral density (BMD) of the lumbar spine in a cohort of 540 healthy, postmenopausal women.
  
  
  METHODS
  Women were selected who experienced long-term lactation (n = 155, median 18 months) or short-term lactation (n = 168, median 3 months) or who were parous, nonlactating subjects (n = 217). The groups were homogeneous in age and differed in body mass index, parity and age at menopause. Vertebral BMD was measured by x-ray absorptiometry.
  
  
  RESULTS
  No statistically significant difference in BMD was found between groups or after adjusting for body mass index, number of live births and age at menopause. Even when the 86 women with the longest lactation history (median 22 months) were matched with 112 parous women with the same parity who did not lactate, we could not find any significant difference.
  
  
  CONCLUSIONS
  Long-term lactation did not significantly affect postmenopausal vertebral BMD in a cohort of healthy women.
authors.affiliation: Division of Rheumatology and Radiology, Istituto Ortopedico Gaetano Pini, University of Milan, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Sinigaglia
authors.forename: M
authors.initials: M
authors.lastname: Varenna
authors.forename: L
authors.initials: L
authors.lastname: Binelli
authors.forename: M
authors.initials: M
authors.lastname: Gallazzi
authors.forename: G
authors.initials: G
authors.lastname: Calori
authors.forename: R
authors.initials: R
authors.lastname: Ranza
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000704:Analysis of Variance; D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology*; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D007774:Lactation; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology*; D008875:Middle Aged; D017698:Postmenopause / Q000502:physiology*; D012016:Reference Values