Childbirth educator, doula and midwife apprentice Cole Deelah recently posted her thoughts on the beauty of vernix caseosa on her blog site Sage Beginnings. Referencing a 2004 study published in ACOG's Journal of Obstetrics and Gynecology, Deelah reminds us of the protective benefits vernix provides to the fetus and newborn - some of which include antimicrobial activity and maintenance of skin hydration following birth. I'd like to look a little deeper into the benefits of vernix, and make a case for rubbing in versus washing off this innate host defense substance.

The 2004 study, referenced above, came out of Cincinnati Children's Hospital by Dr. Henry Akinbi, et. al, and looked at the type, function and distribution of antimicrobial peptides (protein building blocks) contained in both vernix caseosa and amniotic fluid (AF). Despite some concerns[i] over this study, I found the methods of analysis and conclusion intriguing: in the [suspected] absence of chorioamnionitis, vernix and AF contain a mixture of antimicrobial peptides which are biologically active against several common bacteria and fungal agents. Specific antigens tested included E. coli, Group B Strep, Staph aureus, Pseudomonas aeruginosa, Candida albicans, Listeria monocytogenes, Serratia marcescens and Klebsiella pneumonia. Without diving into the microbiology of these nasty agents, I will simply remind you these make up the lion's share of microbes that can cause severe diarrheal illness, pneumonia and meningitis in the newborn (or anyone, for that matter). The assumption this study was chasing involved the idea that the sebaceous (oil) glands of the fetus produce these peptides during the third trimester to act as a host defense mechanism, providing a barrier-type protection from the above-listed agents while in utero. Of interest to me, was the discovery that the combined amount anddistribution of these peptides (think: natural antibiotics) in both AF and vernix were found to be most effective against the bacterial and fungal microbes when compared to the successful antimicrobial activity of each peptide subset, alone.

Likewise, another interesting finding brought forth in the Comments section of the study was the fact that the immune proteins found in vernix and AF are similar to those found in breast milk. The researchers linked this to the evolutionary similarity between mammary glands and cutaneous (skin) glands.

Furthermore, it has been known for some time that as pulmonary surfactant levels increase in the amniotic fluid, vernix begins to detach from the fetal skin - increasing its components into the surrounding AF.[ii],[iii] As the fetus continues swallowing and 'practice breathing' in the womb, this antimicrobial peptide-rich mixture enters the fetal lungs and digestive tracts. The postulation I draw here, which is also hinted at in this study, is the likelihood that the vernix-AF antimicrobial peptide mixture prepares the GI tract for acceptance of the similar peptides found in breast milk - thereby preparing for the process of establishing normal flora within the gut (and perhaps digestion processes, themselves) and prepping the immune system for an important, pending transition. In short, a heightened defense mechanism plays a key role in making the transition from purely innate defense barrier mechanisms to adaptive defense mechanisms.

These findings are furthered by this 2005 study which appeared in Cellular and Molecular Life Sciences 2005(62: 2390-2399). With the goal to not only confirm the presence of the 20 different protein host-defense-enabled-proteins which had been isolated in previous studies, this study also looked at the interaction between proteins and lipids (fats) found in vernix. We have known for some time (and likely taught to our pregnant students/patients) that the fatty, creamy nature of vernix acts as a moisture protectant to the fetus while in utero - not to mention (if rubbed into the skin immediately following birth) a wonderful emollient to prevent excessive drying of the newborn skin in the days following birth. But this study by M. Tollin, et. al discovered that the lipid component of vernix actually enhances the functionality of the antimicrobial peptides.

One of the peptides identified in the process of Tollin's study is the Human Cationic Peptide LL-37. This particular peptide works both as an innate defense mechanism and an adaptive one. As a result, vernix caseosa contains a microbiological element that helps a fetus (and then, newborn) bridge that gap between basic and complex(adaptive) immune function.

The Tollin study proved to have some additional methodological benefits. While still small in numbers (vernix samples were analyzed from eighty-eight newborns; n=88) the analyses were done following vaginal births and vernix-AF analysis was completed on like mother-baby duos. Similar to findings in the '04 study, the interaction of antimicrobial peptides in both the vernix and AF displayed heightened effectiveness in comparison to isolated peptides from AF and vernix samples alone. Because the 2004 study examined AF and vernix samples from immediate post cesarean birth participants, and the 2005 study assessed samples from vaginal birth participants, an appropriate follow-up study might be to compare innate and adaptive antimicrobial effectiveness between babies born via cesarean section versus vaginal birth.

The second study discussed here revealed similar results in the effectiveness of antimicrobial activity against several bacteria and fungi - found to be colonized on the newborn skin within minutes of birth (samples were collected immediately following birth, before any wiping/washing off was performed). Additionally, the study authors postulated that

'The antimicrobial property of vernix may also act to facilitate colonization of normal flora following birth and to block colonization of unwanted microbes or pathogens. For example, psoriasin which is identified in vernix, directly kills E. Coli...'

So... how do we implement all of this into our own practices? My suggestion: teach the expectant parents with whom we interact the enormous benefits contained in that cream cheesy stuff their babies will be covered in (to one degree or another) following birth. Encourage them to facilitate or request rubbing the vernix into the baby's skin, rather than wiping/washing it all off. Born covered in a complex of antibacterial and antifungal elements, babies bring with them into the world additional mechanisms to boost their own immune function than what we once thought.

Posted by: Kimmelin Hull, PA, LCCE

[i] This was a small study (n=35, total) in which vernix and amniotic fluid samples were analyzed from different patients rather than analyzing antimicrobial peptides in the vernix and AF from the same mother-baby duo. Additionally, and consistent with the study's stated objective to analyze these components in the absence of chorioamnionitis, clinical assessment was utilized only to rule out intra-uterine infection vs. confirming the absence by culture. As stated in the study's Comments section, 'Because none of the samples were cultured to confirm the absence of infection, antimicrobial peptides observed in this study might have been induced secondary to subclinical infection.'

[ii] Goldman AS. Evolution of the mammary gland defense system and the ontogeny of the immune system. J Mammary Gland Biol Neoplasia 2002; 7:277-89

[iii] Narendran V, Pcikens W, Wickett R, Hoath S. Interaction between pulmonary surfactant and vernix: potential mechanism for induction of amniotic fluid turbidity. Pediatr Res 2000; 48: 120-4

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