Transepidermal water loss in newborn infants. VIII. Relation to gestational age and post-natal age in appropriate and small for gestational age infants.

In 68 appropriate for gestational age (AGA) and 33 small for gestational age (SGA) infants, transepidermal water loss was studied during the first four weeks after birth. The method used to measure evaporation rate is based on measurement of the water vapour pressure gradient close to the skin surface. All measurements were made at an ambient humidity of 50% and with the infants calm and quiet. At all the investigated post-natal ages in both AGA and SGA infants, an exponential relationship was found between transepidermal water loss (g/m2 h) and gestational age, this loss being much higher in the pre-term infants than in those born at term. The transepidermal water loss was generally lower in SGA than in AGA infants during the first week of post-natal life, irrespective of gestational age at birth. There was a gradual decrease in transepidermal water loss with increasing post-natal age in both pre-term AGA and pre-term SGA infants. Three weeks after birth this water loss tended to be higher in pre-term SGA infants than in pre-term AGA infants of corresponding gestational age.