746 - Postnatal Skin Maturation in Infants ≤25 weeks gestational age

Publication Number: 2727.746

Caitlin M. Stoll, University of Texas Medical Branch School of Medicine, Houston, TX, United States; Samarchitha Magal, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, TX, United States; Sepideh Saroukhani, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, TX, United States; Maggie Aucoin, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, TX, United States; Matthew Rysavy, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, TX, United States

Background: The skin of premature infants is a vital barrier. Infants ≤25 weeks' gestation are highly vulnerable to fluctuations in intravascular volume and body weight due to transepidermal water loss (TEWL) from immature skin.

Objective: We aimed to describe postnatal changes in TEWL and skin hydration through 36 weeks' postmenstrual age as indicators of insensible water loss and skin barrier development in infants ≤25 weeks.

Design/Methods: This prospective cohort study enrolled infants born at 22-25 weeks' gestation at a quaternary academic hospital (November 2024-September 2025). TEWL (g/m²/h) and skin hydration (arbitrary units, AU) were measured under clinical conditions at the ventral forearm, peri-xiphoid chest, and dorsal thigh on approximately postnatal days 3, 7, 14, and 28- and 36-weeks' postmenstrual age. TEWL was measured using a noninvasive open-chamber probe (Tewameter Hex, Courage+Khazaka) and hydration by capacitance (Corneometer, Courage+Khazaka). TEWL was standardized to 50% relative humidity using the Sedin method. Infant characteristics, including daily weights and daily fluid balance, were summarized.

Results: Twenty-nine infants were enrolled; three died during the study period (Table 1). Median TEWL decreased approximately threefold between postnatal days 3 (median [intraquartile range]: 55 [37.7-84.4] g/m²/h) and day 14 (18.6 [15.8-21.7]) and reached a level similar to reference data for term infants by 36 weeks PMA (~10-12 g/m²/h). Between-infant variability in TEWL also substantially decreased over time (Table 2). Skin hydration was initially high (64.3 [35.9, 77.1] AU), reached a nadir around day 7 (21.8 [13.6, 37.1]), and then increased, returning to near baseline at 36 weeks' PMA (53.1 [44.7, 64.9]; (Figure3).

Conclusion(s): Infants ≤25 weeks' gestation exhibit rapid postnatal maturation of skin barrier function, with TEWL declining sharply in the first two weeks and stabilizing thereafter and skin hydration rapidly decreasing and slowly returning to baseline. Our findings underscore dynamic early skin barrier adaptation and the importance of developmental and anatomic factors in insensible water loss, informing early neonatal fluid management strategies.

Patient Demographics


Transepidermal Water Loss and Clinical Management
Data shown as median [intraquartile range]. PMA=postmenstrual age; TEWL=transepidermal water loss; TFI=total fluid intake; UOP=urine output

Postnatal Changes in Transepidermal Water Loss and Skin Hydration