Body water distribution in newborn infants appropriate for gestational age

Total body water (TBW), extracellular water (ECW) and intracellular water (ICW) were measured within 6 h of birth in 99 appropriate for gestational age (AGA) infants. The two groups of infants included were term (mean +/- SD gestation 272 +/- 7 days) and preterm (mean +/- SD gestation 238 +/- 11 days) infants. The mean TBW +/- SD was 777 +/- 26 ml/kg in preterm infants and 737 +/- 26 ml/kg in term infants. The corresponding ECW was 349 +/- 26 ml/kg and 331 +/- 30 ml/kg respectively. Weight was the best correlate of TBW (r = 0.98) and ECW (r = 0.92) volumes. TBW per unit of body weight showed significant decline with increasing gestation (r = -0.54) and birth weight (r = -0.51). ICW per kg showed a moderate correlation with TBW (r = 0.63), whereas ECW per kg had a low correlation (r = 0.35) with it. TBW/kg in our infants was comparable to infants from other ethnic groups. ICW/kg, however, was consistently higher and ECW/kg lower at all stages of maturation in Indian infants as compared to Caucacian and Negroid infants.