Submitted to: Pediatrics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/1994
Publication Date: N/A
Interpretive Summary: Much of our knowledge of early human growth and development is based on information from old studies of fetuses from nearly 100 years age. Rarely has the whole body been examined in early life, and when it has, there have been discrepancies in the reported values for body composition. Because of these differences and the development of non-destructive techniques, we wanted to provide new, accurate data regarding the total body composition of infants. Using state-of-the-art procedures, we studied infants immediately after death. Our study results provide new, useful information about growth during early life. We have confirmed the general validity of the older models of fetal growth, and also have indicated the areas of needed development for newer nutritional strategies for low-birth-weight infants.
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 3280g; gestational ages ranged from 24 to 42 weeks. Total body composition was determined using the nondestructive in- situ procedures of 40K counting and neutron activation analysis. The absolute amounts of K, Ca, P, Na, and Cl were measured. Although body Cl 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. Furthermore, those infants whose survival was brief had reduced body K, and index of body cell mass. All elements except body Cl 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 weight. The two preterm infants who survived for more than 10 weeks had significantly reduced bone growth as shown by their Ca and P deficiencies.