title: Bed rest and other determinants of bone loss during pregnancy.
abstract: OBJECTIVE
  The purpose of this study was to evaluate patterns of bone loss during pregnancy and potential influences.
  
  
  METHODS
  This was a prospective study of 181 women receiving prenatal care at Magee-Womens Hospital or its auxiliary clinics in Pittsburgh, Pennsylvania, between 1992 and 1995. Bone mineral density was measured at approximately 16 and 36 weeks' gestation.
  
  
  RESULTS
  Trabecular, but not cortical, bone loss occurred during pregnancy. Mean ultra-distal bone mineral density loss was 1.9% (95% CI 1.2-2.5) during the 20-week period. Women prescribed bed rest had an adjusted mean loss of 4.6% compared with 1.5% for women not prescribed bed rest ( P = .001) and 6-fold higher odds ( P = .001) of bone loss > or =5% during the 20-week period. Nulliparity, calcium intake < 2 000 mg/day, low weight gain, and maternal age < 21 or >30 years were more modestly associated with greater bone loss.
  
  
  CONCLUSIONS
  Substantial trabecular bone loss may occur during pregnancy, particularly in women prescribed bed rest. Study of postpartum bone recovery in such women is needed.
authors.affiliation: Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, NC, USA. promisl1@niehs.nih.gov
authors.forename: Joanne H E
authors.initials: JH
authors.lastname: Promislow
authors.forename: Irva
authors.initials: I
authors.lastname: Hertz-Picciotto
authors.forename: Margaret
authors.initials: M
authors.lastname: Schramm
authors.forename: Margaret
authors.initials: M
authors.lastname: Watt-Morse
authors.forename: John J B
authors.initials: JJ
authors.lastname: Anderson
mesh_terms: D000293:Adolescent; D000328:Adult; D001510:Bed Rest; D015519:Bone Density; D002136:Calcium, Dietary / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008423:Maternal Age; D011247:Pregnancy / Q000502:physiology*; D011261:Pregnancy Trimester, First; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D015430:Weight Gain
chemical_list: D002136:Calcium, Dietary