title: Impact of intra- and extrauterine growth on bone mineral density and content in the neonatal period of very-low-birth-weight infants.
abstract: BACKGROUND
  Very-low-birthweight infants (VLBWIs) are at high risk for suboptimal bone mineral density (BMD) and bone mineral content (BMC). Small-for-gestational-age (SGA) status also causes reduced bone mineralization in full-term infants. However, the impact of intrauterine and postnatal extrauterine growth on BMD and BMC in VLBWIs is inconclusive.
  
  
  METHODS
  We retrospectively investigated n=68 VLBWIs, comprising 45 appropriate-for-gestational-age (AGA) and 23 SGA infants who underwent lumbar spine dual-energy X-ray absorptiometry at term-equivalent age.
  
  
  RESULTS
  BMD and BMC did not differ between AGA and SGA VLBWIs. Subgroup analyses of infants with birthweight<1000 g vs 1000-1500 g, and GA<27 weeks vs ≥ 27 weeks also showed no differences in BMD and BMC between AGA and SGA infants. In contrast, infants with extrauterine growth restriction (EUGR) showed significantly lower values than those without (BMD: 0.124 ± 0.023 vs 0.141 ± 0.032 g/cm(2), P=0.02; BMC: 0.80 ± 0.26 vs 0.94 ± 0.23 g, P=0.04). There were no differences between AGA and SGA infants with EUGR. However, in the AGA cohort, infants with EUGR showed significantly lower values than those without (BMD: 0.121 ± 0.022; 0.141 ± 0.03 g/cm(2), P=0.02; BMC: 0.73 ± 0.23 vs 0.94 ± 0.23 g, P=0.005). Multiple regression analyses showed GA, weight and head circumference at birth, and weight percentile at term correlated with term BMD. Conversely, only weight percentile at term significantly correlated with term BMC.
  
  
  CONCLUSIONS
  EUGR, rather than IUGR, is a risk factor for reduced BMD and BMC in the neonatal period in VLBWIs.
authors.affiliation: Department of Pediatrics, Yodogawa Christian Hospital, Osaka, Japan; The Ritchie Centre, Hudson Institute of Medical Research, Monash University, Clayton, VIC Australia. Electronic address: s-ri@hotmail.co.jp.
authors.forename: Jingang
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Pediatrics, Yodogawa Christian Hospital, Osaka, Japan.
authors.forename: Masahisa
authors.initials: M
authors.lastname: Funato
authors.affiliation: Department of Pediatrics, Yodogawa Christian Hospital, Osaka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tamai
authors.affiliation: Department of Pediatrics, Yodogawa Christian Hospital, Osaka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Wada
authors.affiliation: Department of Pediatrics, Yodogawa Christian Hospital, Osaka, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Nishihara
authors.affiliation: Department of Pediatrics, Yodogawa Christian Hospital, Osaka, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Morita
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research, Monash University, Clayton, VIC Australia; The Department of Obstetrics and Gynaecology, Monash University, Clayton, VIC Australia.
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: Miller
authors.affiliation: Department of Neonatal Intensive Care Unit, Yodogawa Christian Hospital, Osaka, Japan.
authors.forename: Kayo
authors.initials: K
authors.lastname: Egashira
mesh_terms: D015519:Bone Density; D001846:Bone Development; D005260:Female; D005317:Fetal Growth Retardation / Q000473:pathology*; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight / Q000254:growth & development*; D008297:Male
keywords: Bone mineral content; Bone mineral density; Extrauterine growth; Intrauterine growth; Small-for-gestational-age; Very-low-birthweight