Biomedical assessment and instrumental evaluation of healthy infant skin.

The skin forms a critical structural boundary and a perceptual interface for the organism, yet the definition "healthy skin" is surprisingly difficult to describe. The present study's goal was to generate a technical definition of healthy infant skin by quantifying specific biophysical parameters before and after bathing in infants and correlating such parameters to a perceptual maternal evaluation. Fifty-two healthy infants, 3-6 months old, were evaluated before and after freshwater bathing. Diapered skin had a higher transepidermal water loss (TEWL), surface hydration, moisture accumulation rate (MAT), and friction than nondiapered skin before the bath (p < 0.01). Bathing dramatically altered the biophysical properties at both skin sites, with decreased MAT and lower friction, indicating a drier skin surface (p < 0.01). Visual redness and dryness decreased after bathing (p < 0.01). Blinded grading of optical images showed a significant preference for the skin after bathing (p < 0.01). This study provides the first quantitative technical definition of healthy infant skin with positive correlation to perceptual assessment by independent observers (mothers). The findings support the hypothesis that water binding properties of the stratum corneum are altered by occlusion (diapering) and that bathing introduces acute changes in stratum corneum water interactions, leading to a drier skin surface and a preferred skin appearance.