Effects of prematurity, intrauterine growth status, and early dexamethasone treatment on postnatal bone mineralisation.
OBJECTIVE
To examine the hypothesis that, apart from prematurity, intrauterine growth status (expressed as gestational age specific birth weight standard deviation scores), neonatal factors, and duration of dexamethasone treatment influence bone mineralisation in early infancy.


METHODS
In this prospective study, groups consisted of 15 preterm small for gestational age infants (SGA group) and 43 preterm appropriate for gestational age infants (AGA group). A reference group contained 17 term infants. Body size is known to affect bone mineral content (BMC), therefore postnatal bone mineralisation was measured when the study infants and controls had attained a similar body size. Bone mineral density (BMD) and BMC were determined by dual energy x ray absorptiometer of the lumbar spine (L2-L4).


RESULTS
Both preterm groups had significantly lower BMC and BMD than the weight matched term reference group, but no difference was found in BMC and BMD between preterm SGA and AGA infants. In stepwise regression analysis, bone area, duration of dexamethasone treatment, weight at examination, and weight gain per week were the most significant factors, explaining 54% of the variance of the BMC values.


CONCLUSIONS
In particular, weight at examination, prematurity, and possibly dexamethasone treatment, but not intrauterine growth status, affect postnatal bone mineralisation.
Kurl
S
S
Department of Paediatrics, Kuopio University Hospital, PO Box 1777, 70211 Kuopio, Finland. skurl@messi.uku.fi
Heinonen
K
K
Länsimies
E
E
D015502:Absorptiometry, Photon; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D001824:Body Constitution; D015519:Bone Density / Q000502:physiology*; D002113:Calcification, Physiologic / Q000187:drug effects / Q000502:physiology*; D016022:Case-Control Studies; D002908:Chronic Disease; D003907:Dexamethasone / Q000627:therapeutic use*; D005314:Embryonic and Fetal Development; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D007236:Infant, Small for Gestational Age / Q000502:physiology*; D008171:Lung Diseases / Q000188:drug therapy; D008297:Male; D011446:Prospective Studies; D012044:Regression Analysis
D000893:Anti-Inflammatory Agents; D003907:Dexamethasone