Submitted to: Annals of Human Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/1994
Publication Date: N/A
Interpretive Summary: Much of our knowledge of the prematurely born infant is based on older studies of fetuses performed nearly a century ago. Growth of an infant after a premature birth is not the same as if it had stayed in the mother's womb. We wanted to provide new and accurate data about the chemical content of the premature infant. We studied infants covering a wide range of birth weights and gestational ages. Although there was general validity of the older models of growth, the current study indicated that newer nutritional strategies are needed to meet the minimal requirements of normal growth for the low-birth-weight infant.
Technical Abstract: The body composition of 23 infants was examined at postmortem. All infants were live births and lived from 1 to 192 days. Their body weights at birth ranged from 480 to 3280 g; gestational ages ranged from 24 to 42 weeks. Total body composition was determined using the nondestructive in-situ procedures for 40K counting and neutron activation analysis. The absolute amounts of K, Ca, P, NA and C1 were measured. Although body C1 was in general agreement with estimates for the reference fetus 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 levels agreed with the reference fetus. Furthermore, those infants whose survival was brief had reduced body K, an index of body cell mass. All elements except body C1 were linearly related to fat-free mass (FFM). The correlations with gestational age were non-significant when the variation in elemental content was accounted for by FFM or body wt. The two preterm infants who survived for more than 10 weeks had significantly reduced bone growth as shown by their Ca and P deficiencies.