Changes in skin barrier over the first four days of life: a cross-sectional study

We aimed to evaluate the trajectory of skin barrier properties in full-term newborns during the first four days after birth.

Based on the MKNFOAD cohort (NCT02889081), transepidermal water loss (TEWL), stratum corneum hydration (SCH), skin pH, and sebum content at five anatomical sites (cheek, forehead, volar forearm, abdomen, and dorsal lower leg) were examined once within 96 h after birth in 384 full-term infants. Multivariable linear regression analysis was performed to assess variations in these skin barrier parameters with age adjusted for gestational age, neonate's sex, parents' allergy history, delivery mode, amniotic fluid characteristics, and birth weight. The regression coefficient (ß) and 95% confidence interval were reported.

We analyzed a total of 384 neonates including 198 (51.6%) boys. TEWL values remained stable and showed no significant association with age (days). pH values exhibited a declining trend with age (p for trend <0.001). Both SCH values and sebum content grew with age (p for trend <0.001).

During the first four days after birth, the skin TEWL remained stable, pH decreased, and the SCH and sebum content increased over time. These findings provide insights into the neonatal skin physiological development at the beginning of life.

From birth to 96 h, TEWL was stable, pH showed a steep decline, SCH and sebum content increased. This study provides the first evidence of skin adaptation in the newborn due to changes in utero to after birth in the first 4 days of life in an Asian population. These findings will provide a new theoretical basis for neonatal skin physiology and clinical strategies for guiding newborn skin care.