Objectives: To test the hypothesis that the level of relative humidity (RH) in which preterm infants are nursed might influence their postnatal skin maturation.
Study design: In 22 preterm infants (GA 23-27 weeks), transepidermal water loss (TEWL) was determined at postnatal ages (PNA) of 0, 3, 7, 14, and 28 days. At a PNA of 7 days, the infants were randomized to care at either 50% or 75% RH.
Results: TEWL decreased at a slower rate in infants nursed at the higher RH. At a PNA of 28 days, TEWL was about twice as high in infants nursed at 75% RH (22 +/- 2 g/m2 h) than in those nursed at 50% RH (13 +/- 1 g/m2 h; P < .001).
Conclusions: The results indicate that the level of RH influences skin barrier development, with more rapid barrier formation in infants nursed at a lower RH. The findings have an impact on strategies for promoting skin barrier integrity in extremely preterm infants.