Measurement of transepidermal water loss in Tanzanian cot-nursed neonates and its relation to postnatal weight loss.

In healthy cot-nursed Tanzanian neonates (n = 92, gestation 26-42 weeks) measurements of trans-epidermal water loss (TEWL) and weight change were performed during the first 24 h after birth at an average ambient humidity of 70% and an environmental temperature of 32 degrees C. Urine production on day 1 (ml/kg per 24 h) was documented for a subgroup of 13 preterm and 8 term infants. In a limited group of preterm infants (n = 5) TEWL measurements, weight and 24 h urine volume measurements were repeated daily for 7 days. Maximum weight loss was determined in 7 preterm (gestational age 30-36 weeks) and 6 term infants. TEWL was estimated by measuring the evaporation rate at three sites of the body using the water vapour pressure gradient method. On day 1, TEWL was highest in the most preterm infants, whereas TEWL and urine production were higher in large for gestational age infants as compared to appropriate for gestational age (AGA) infants of the same gestational age (31-36 weeks). For the whole group, weight loss on day 1 was correlated with TEWL (r = 0.49, p < 0.05). At follow-up TEWL in preterm infants remained almost constant during the first 4 days and decreased after the fourth day, at which time weight gain commenced. Preterm AGA infants (gestational age 24-37 weeks) showed a mean postnatal weight loss of 4.4% of the birth weight, while in term infants this loss was only 2.6%. A reduced postnatal weight loss as compared to Caucasian infants may be explained by a lower water loss during the first days after birth, through both skin evaporation and urine excretion.