Use of a body proportionality index for growth assessment of preterm infants.
OBJECTIVE
To evaluate the utility of weight-for-length (defined as gm/cm(3), known as the "ponderal index") as a complementary measure of growth in infants in neonatal intensive care units (NICUs).


METHODS
This was a secondary analysis of infants (n=1214) of gestational age 26 to 29 weeks at birth, included in a registry database (1991-2003), who had growth data at birth and discharge. Weight-for-age and weight-for-length were categorized as small (<10th percentile), appropriate, or large (>90th percentile).


RESULTS
Statistical agreement between the weight-for-age and weight-for-length measures was poor (kappa=0.02 at birth, 0.10 at discharge; Bowker test for symmetry, P< .0001). From birth to discharge, the percentage of small-for-age infants increased from 12% to 21%, the percentage of small-for-length infants decreased from 10% to 4%, the percentage of large-for-age infants remained similar (<1%), and the percentage of large-for-length infants increased from 5% to 17%. At discharge, 92% of the small-for-age infants were appropriate or large-for-length, and 19% of the appropriate-for-age infants were large-for-length.


CONCLUSIONS
Weight-for-age and weight-for-length are complementary measures. Weight-for-length or other measures of body proportionality should be considered for inclusion in routine growth monitoring of infants in the NICU.
Olsen
Irene E
IE
Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA. irene.olsen@drexel.edu
Lawson
M Louise
ML
Meinzen-Derr
Jareen
J
Sapsford
Amy L
AL
Schibler
Kurt R
KR
Donovan
Edward F
EF
Morrow
Ardythe L
AL
D000367:Age Factors; D000886:Anthropometry / Q000379:methods*; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007228:Infant Nutrition Disorders / Q000517:prevention & control*; D007231:Infant, Newborn; D007234:Infant, Premature / Q000254:growth & development*; D019102:Infant, Very Low Birth Weight / Q000254:growth & development*; D007363:Intensive Care Units, Neonatal; D008297:Male; D009820:Ohio; D015203:Reproducibility of Results