Successful adaptation following birth in humans requires mechanisms for coupling between the infant and a terrestrial environment. In earlier work, we have focused on the outermost layer of the skin, the stratum corneum (SC), as a primary site of organism-environmental coupling required for temperature and infection control, water balance, and behavioral interactions. Using bioinstrumental quantification, we have documented a series of adaptive responses of this complex biopolymeric interface during the first few days of life. In this study, we measured transepidermal water movement (TEWM) as the change of surface electrical capacitive reactance (Pediatrics 96:688-692, 1995) and surface acidity (using a Courage & Khazaka skin surface pH meter). SC changes were evaluated in 32 term newborn infants over the first 2 hours of life. The skin was studied in a time dependent manner over the chest (after exposure to radiant warmer) and the back (a nonexposed surface). Measurements were correlated with optical imaging of the same sites using both macrophotography (TransLite Nevoscope) and desquame analysis(CuDerm, Dallas Tx). Infants were examined initially 92 mins after birth(minimum of 21 mins under radiant warmer) and subsequently 147 mins after birth (74 mins under RW). The results demonstrate: 1) TEWM was initially lower over the chest than the back, 0.9±0.2 vs 2.0±0.5 cru's/sec, mean± SE, p≤ 0.05; 2) TEWM decreased temporally at both sites but only the chest correlated significantly with time under the radiant warmer, p≤ 0.05; 3) skin pH was lower over the back than the chest at the time of the initial measurement, 6.8±0.1 vs 7.1±0.1, p≤ 0.01; 4) skin pH decreased in the first hour of life with the most significant changes over the chest, p≤ 0.01; 5) Optical imaging corroborated expert skin grades and showed early desquamation, particularly over skin surfaces exposed to the radiant warmer.
Conclusions: The skin surface of the newborn infant exhibits programmatic changes in hydration and acidity which are initiated at the time of birth. Care practices (infant position, removal of vernix, swaddling, radiant warming, etc.) may have great influence on both the site and rate of these changes.
