BODY-COMPOSITION OF THE PRETERM INFANT

The body composition of 23 infants was examined at postmortem. All inf ants were live births and lived from 1 to 192 days. Their-body weights at birth ranged from 480 to 3280g; gestational ages ranged from 24 to 42 weeks. Total body composition was determined using the nondestruct ive in-situ procedures of K-40 counting and neutron activation analysi s. The absolute amounts of K, Ca, P, Na, and Cl were measured. Althoug h body Cl was in general agreement with estimates for the reference fe tus model, body K and Na values were lower. Body Ca content was higher than the reference fetus at body weights above 2 kg, yet body P level s agreed with the reference fetus. Furthermore, those infants whose su rvival was brief had reduced body K, an index of body cell mass. All e lements except body Cl were linearly related to fat-free mass (FFM). T he correlations with gestational age were non-significant when the var iation in elemental content was accounted for by FFM or body weight. T he two preterm infants who survived for more than 10 weeks had signifi cantly reduced bone growth as shown by their Ca and P deficiences.