title: Ultrasonographic bone characteristics during normal pregnancy: longitudinal and cross-sectional evaluation.
abstract: OBJECTIVE
  We evaluated the pattern of bone density during pregnancy by radiation-free ultrasonographic densitometry.
  
  
  METHODS
  In a longitudinal study we measured bone mineral density in a group of 10 normal primiparous women, from the fourteenth to the thirty-eighth weeks of pregnancy. In a cross-sectional study bone mineral density was determined in a group of 85 normal primiparous women, in different weeks of pregnancy.
  
  
  RESULTS
  In the longitudinal study ultrasonographic bone density was stable in the first part of pregnancy, whereas a significant (p < 0.05) decrease was evidenced during the third trimester. A negative correlation between bone density and weeks of pregnancy (p < 0.0001) was evidenced in the cross-sectional study.
  
  
  CONCLUSIONS
  During physiologic pregnancy the calcium mobilization from the maternal bone stores to accomplish the fetal needs can cause a significant decrease in maternal bone density in the last trimester of gestation.
authors.affiliation: Department of Obstetrics and Gynecology Piero Fioretti, University of Pisa, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Gambacciani
authors.forename: A
authors.initials: A
authors.lastname: Spinetti
authors.forename: R
authors.initials: R
authors.lastname: Gallo
authors.forename: B
authors.initials: B
authors.lastname: Cappagli
authors.forename: G C
authors.initials: GC
authors.lastname: Teti
authors.forename: V
authors.initials: V
authors.lastname: Facchini
mesh_terms: D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D011247:Pregnancy; D012044:Regression Analysis; D013997:Time Factors; D014463:Ultrasonography