Preterm Infant Skin Structure Is Qualitatively and Quantitatively Different From That of Term Newborns

The immature skin of preterm infants is uniquely vulnerable to pressure and chemical injury. We sought to qualitatively and quantitatively describe the histopathologic patterns of skin development in preterm infants.

Autopsy skin samples were examined for 48 liveborn preterm infants born at 18+ to 36 weeks, and control groups of term neonates and older infants/children. Quantitative variables included thickness of the stratum corneum, epidermis, and dermis. Qualitative features included stratum corneum, rete ridges, and hair follicles.

Patterns of maturation were reproducible. Compact keratin appeared beginning at 21-22 weeks. Basketweave keratin appeared first around hair follicles, and then became more generalized from ∼28 weeks corrected gestational age (CGA) onward. Rete ridges began to appear at ∼30 weeks. Epidemal and dermal thickness increased with age. Infants who survived ≤7 days had thicker dermis than those who survived longer, even adjusted for CGA.

Skin development in preterm infants has reproducible milestones. Significant structural changes occurring around 28-30 weeks may improve barrier function, with implications for use of topical compounds such as chlorhexidine. The findings also highlight challenges in evaluating pressure injuries in preterm infants, and postnatal changes in skin parameters.