Stratum corneum maturation. A review of neonatal skin function.

The importance of the stratum corneum and its barrier function for infants, especially for newborns, is clinically evident. Research regarding the maturation of the stratum corneum in neonates, i.e. when full barrier function is obtained, has produced varying results. Based on transepidermal water loss and percutaneous absorption studies, term infants seem to possess stratum corneum with adult barrier properties. Additionally, postnatal life is thought to accelerate stratum corneum maturation, so that even preterm infants have barrier function similar to term infants at 2-3 weeks of gestational age. However, a look at other parameters, such as skin thickness, skin pH and stratum corneum hydration, shows that neonatal skin is always adjusting to the extrauterine environment in contrast to the steady state of adult skin. This suggests that barrier stabilization may be dependent on achieving a balance between different parameters. However, it is still in question, which parameters, what balance and what timing. This paper provides an up-to-date overview on the neonatal skin barrier based on the review of current literature.