Unraveling the Mystery of Vernix Caseosa

Unraveling the Mystery of Vernix Caseosa

‘Vernix’ = to varnish. ‘caseous’ = cheesy nature.1

According to present knowledge, vernix production is unique to humans. Vernix caseosa is a naturally occurring substance covering the skin surface of the fetus in the last trimester of pregnancy. Its amount and distribution on the infant’s skin at birth are highly variable and can reflect the intimate maternal and fetal interactions. Vernix provides multiple overlapping maturational functions for the development of skin in utero and post-birth adaptation. It is produced in part by fetal sebaceous glandsand consists of water (81%), lipid (9%), and proteins (10%). 

Properties of vernix for the fetus

Vernix performs an epidermal barrier function in utero to facilitate epidermal growth underneath it and acts as a hydrophobic barrier against amniotic fluid maceration and loss of fluids and electrolytes. Vernix also acts as a protective biofilm by minimizing friction of fetal parts during delivery and as an antimicrobial cover against the bacteriologically rich environment of the mother's genital tract along with the insulating effect on the fetus. Vernix, like the epidermis, has a direct role in defense against bacteria. Vernix is implicated in the maintenance of airway bacterial homeostasis and against intra-uterine infection. The broad-spectrum action of many of the proteins in vernix may aid in avoiding the development of resistance in bacterial pathogens.

The vernix within amniotic fluid when swallowed by fetus has potential effects on the developing gut. 

Retention of Vernix in Skin Care of Newborn Infant

 Skin moisturizer: because of its high-water content, vernix retention after birth results in significantly more hydrated skin surface. Vernix acts as an agent to moisturize the stratum corneum. Comparison with various barrier creams like Petrolatum, Aquaphor, and Eucerin, shows vernix to be having higher water content. 

Wound healing properties: Vernix has shown to increase skin metabolism by increasing glucose consumption and lactate production. The regulation of transepidermal water gradient is known to be important in the formation of the epidermal barrier and skin regeneration following wounding

As part of the initial newborn care, nurses traditionally wipe vernix caseosa from wet skin. As thermoregulation and resuscitation are the priorities of care, wiping of skin was considered the preferred method for accomplishing drying and stimulation of respiratory effort. As the movement toward evidence-based practice has become a major practice effort, the practice and procedure for this nursing activity have fallen under scrutiny.A multiple-site national study was conducted by the National Association of Neonatal Nursing (NANN) and the Association of Women's Health Obstetrical and Neonatal Nursing (AWHONN) in 1998.A consensus statement based on the results of the study directed “removal of all vernix is not necessary for hygienic reasons” and “vernix may provide antibacterial promotion and wound healing”. Interestingly, the World Health Organization (WHO) also recommends leaving vernix intact on the skin surface after birth. 


Prenatal exercises

Prenatal exercises