Functional skin adaptation in infancy – almost complete but not fully competent

Abstract

Early postnatal life is a period of active functional reorganization and cutaneous physiological adaptation to the extrauterine environment. Skin as the outermost organ of mammalians is endowed of multiple functions such as protection, secretion, absorption and thermoregulation. Birth stimulates the epidermal barrier maturation and the skin surface acidification especially in premature infants. In full-term infants the developed stratum corneum accomplishes competent barrier function, in contrast to prematures. Complete barrier maturation in preterm infants is fulfilled by 2-4 weeks of the postnatal life. However, in preterms with 23-25 weeks gestational age this process takes longer. Versatile regulatory mechanisms, namely skin surface acidity, calcium ion gradient and nuclear hormone receptors ⁄ ligands are interrelated in the complex postnatal newborn adaptation. The skin of newborns is adjusting quickly to the challenging environmental conditions of the postpartum.However, certain functions, for example, microcirculation, continue to develop even beyond the neonatal period, that is, up to the age of 14-17 weeks. Different environmental factors (for instance, dry and cold climate, diapers and cosmetic care procedures) influence the postnatal development of skin functional parameters such as stratum corneum hydration and the permeability barrier especially in premature infants. The aim of this article is to summarize the current knowledge on skin physiology in newborn and infants with a practical approach and to discuss the possible clinical consequences. This review offers the readership a critical and practical overview of skin physiology in newborns and infants. It emphasizes possible new research fields in neonatal and infantile skin physiology.

Effective use of transdermal drug delivery in children

“…On the other hand, the SC of term neonates provides a competent barrier with TEWL similar to that across adult skin [5]. The competence of the full-term infant skin is supported by considerable research, some as early as 1977 [34] which showed that TEWL and carbon dioxide emission rates across the skin of healthy term infants and healthy adults were comparable.…”

“…Briefly, at 4-5 wk GA the ectoderm of the embryo is covered by the periderm; epidermal stratification starts around 8 wk GA, and the development of skin appendages around 12 wk GA [4,5]. The periderm acts as the interface between the amniotic fluid with the developing epidermis prior to SC formation; later the periderm sheds to become part of the vernix caseosa at 15-20 wk GA.…”

“…The differences between infant and adult skin physiology, as well as the development of skin functionality, including the effects of GA and PNA on transepidermal water loss (TEWL), skin surface pH, skin hydration, skin electrical properties, skin structure and roughness and natural moisturizing factor (NMF) abundance, have been recently and extensively reviewed [5,7,[9][10].…”

“…These differences between infant and adult skin physiology have been reviewed [5,7,9] and concern properties such as skin surface pH, skin hydration, skin and SC thickness, desquamation and corneocyte size. Some of these results are based on data from small cohorts and may be difficult to generalise due to differences in methodology and skin sites studied (see [7] for comprehensive details).…”

“…Human skin is responsible for several functions including photoprotection, thermoregulation, hormonal synthesis, sensory perception, and immune and barrier functions [4,5]. Among these, barrier function is the most relevant to drug absorption and not surprisingly, many enhancement techniques have been examined to overcome this challenge [1,6].…”