The skin functions as a protective barrier against harmful pathogenic organisms and toxins, provides thermal regulation and maintains internal fluid balance. At birth, an infant's skin pH is greater than 6.0 but it falls to approximately 4.95 within several days (96 h) of birth.[2,3] A pH less than 5.0 is credited with bacteriocidal properties and serves in defense against microorganisms.
An acidic pH contributes to stratum corneum immune function by inhibiting colonization of pathogens. A rise in skin pH from acidic to neutral causes an increase in the total number of bacteria and a shift in the species present. Increased pH may reduce stratum corneum integrity and may increase its susceptibility to mechanical damage. Some evidence suggests that changes in pH are associated with the prevention and pathogenesis of skin diseases such as atopic dermatitis, irritant contact dermatitis and wound healing.
Premature infants bathed every two to four days had no difference in skin flora or colony counts. Another study of premature infants showed that bathing with cleansers or water reduced colonization for only a brief time.
In addition to hygiene, the initial bath of the baby also removes blood and body fluids which could contaminate health care workers or others in contact with the baby. Until newborns are bathed, universal precautions, including use of gloves by health care workers, are required.
While skin care and bathing practices have traditionally been based on the patient's culture, regional customs and anecdotal experience; more recent evidence-based recommendations have been made and will be presented in this article. Recommendations will include the timing of the first bath, routine bathing frequency, tub versus immersion bathing and considerations for selection of a cleansing agent.
Vernix, unique to humans, is a cheesy white protective covering of the newborn skin in utero. It develops in a cephalocaudal manner beginning at the end of the 2nd trimester with the thickest coating noted between 36 and 38 weeks. Vernix detaches from the skin as the levels of pulmonary surfactant rise, resulting in a progressive increase in the turbidity of the amniotic fluid. Surface distribution depends on gestational age, type of birth, birthweight, race, gender, and the presence of meconium. It is composed of 10% protein, 10% lipids and 80% water. Due to the hydrophobic lipid matrix, it has a surface tension similar to petrolatum without being occlusive. Vernix protects the fetus from the maceration of the amniotic fluid and allows the fetus to move freely in utero without chafing. Additionally, vernix serves a variety of important roles including: protection from infection, decreased skin permeability, pH development, skin cleansing & moisturizing, and wound healing.[11,13,14]
Antimicrobial peptides in vernix may control skin colonization by commensal flora and free amino acids in vernix may act as a trophic factor for the developing gut. The retention of vernix on newborn skin has been shown to assist with the development of the acid mantle, even after bathing with a mild cleanser as long as the vernix was not mechanically removed.[11,14] The World Health Organization and the Neonatal Skin Care Evidence-Based Clinical Practice Guideline recommend leaving residual vernix caseosa intact on the skin and allowing it to wear off with normal care and handling.
NAINR. 2014;14(4):166-170. © 2014 Elsevier Science, Inc.