Published online Jul 26, 2023.
https://doi.org/10.5021/ad.22.098
Comparison of the Effects of Bathing and the Dry Technique on the Skin Condition of Early Neonates: A Prospective Observational Study
,
Seiichi Yoshida,1
Takeo Minematsu,2
Yutaka Hatano,3
Akifumi Notsu,4
and Takamichi Ichinose5
Abstract
Background
In Japan, neonates have typically been bathed in a bathtub immediately after birth because bathing is a custom for cleansing impurities. However, dry technique has been introduced into many institutions since 2000. There is little scientific evidence on the benefit or harmfulness of either method to neonatal skin, and consequently, opinion remains split on which method is superior.
Objective
The purpose of the present study was to determine whether bathing or the dry technique of cleaning is better in maintaining skin health in the early neonatal period.
Methods
Transepidermal water loss (TEWL) and skin pH, considered an index of skin barrier function, were measured in each group. Tumor necrosis factor (TNF)-alpha and interleukin (IL)-6, which are inflammatory cytokines released by keratinocytes, were measured by skin blotting.
Results
TEWL and skin pH of neonates were lower with the dry technique than with bathing. The expression level of IL-6 and TNF-α in chest skin of neonates was higher with bathing than with the dry technique.
Conclusion
These results suggest that the dry technique may maintain skin health better than bathing in the early neonatal period.
INTRODUCTION
The skin thickness of early neonates is just one-third of that of adults. The amount of intercellular lipids in the epidermis is insufficient, the keratin of the horny layer does not mature until 2 to 3 days after birth1, and it takes a few days for the skin pH to become weakly acidic (pH 5.0)2. Consequently, the skin barrier function of early neonates is reduced compared with that of adults, and evidence suggests that they are at risk of developing allergies, bacterial infections, and inflammation caused by antigens and/or bacteria that invade the body by crossing the stratum corneum3, 4, 5, 6, 7. It is therefore important to clean neonates immediately after birth in a manner that is gentle to the skin.
In Japan, neonates have typically been bathed in a bathtub immediately after birth because bathing is a custom for cleansing impurities. However, it has been found that the physical and chemical stimulation and detergents involved in washing increase the risk of skin problems by disrupting its permeability barrier through detrimental effects such as removing the stratum corneum and sebum, dissolving intercellular lipids, and disrupting the balance of the normal flora of the skin8, 9.
The dry technique of cleaning neonates has been used in other countries. Based on the skin care practices for newborns recommended by the American Academy of Pediatrics in 197810, this technique involves only wiping away blood and other debris on the skin of the infant immediately after birth and leaving the vernix caseosa in place. By minimizing skin manipulation, it can reduce heat loss, skin damage, and the opportunity for contact with toxic substances that could have a negative effect on neonatal skin. In addition, the preserved vernix caseosa compensates for the immature skin barrier function during the early neonatal period and serves to maintain normal function through its moisturizing and antibacterial effects. The dry technique has been introduced into many institutions in Japan since 2000. However, more than 60% of institutions still bathe neonates using a detergent on consecutive days starting from 1 day of age11. There is little scientific evidence on the benefit or harmfulness of either method to neonatal skin, and consequently, opinion remains split on which method is superior12, 13, 14. Therefore, this study examined which cleaning method could maintain skin health by examining differences in the maturation of skin barrier function, skin findings, and potential inflammatory reactions in skin tissue with either bathing or use of the dry technique in the early neonatal period.
MATERIALS AND METHODS
Study design and subjects
The study was a prospective observational study conducted at two facilities that provide childbirth services in Japan. The purpose of the study was explained to pregnant females whose antenatal course had been normal and whose expected delivery date was in February or March 2015. Participants provided written informed consent. This study was approved by the Research Ethics Committee of Oita University of Nursing and Health Sciences (approval no. 1058). The directors of each facility and participants were given letters that explained the study including its purpose and what it entailed, the voluntary nature of study participation, protection of privacy, and data use, management, and disposal from an ethical point of view. The mothers or children whose experienced illness during the study were given treatment as a priority and discontinued from the study.
Cleaning method
At facility A, blood was washed off with warm water immediately after birth. Beginning from 1 day of age, neonates were bathed once daily using soap (bath group). At facility B, the dry technique was used immediately after birth to 4 days of age (DT group). Debris and fluid such as blood on the skin of neonates were wiped away and the vernix caseosa was preserved. Neonates were bathed using soap at 5 days of age. Bathing was performed in tubs filled with water at 38℃. Bathing time was 4 to 5 min. At both facilities A and B, a mildly acidic foaming baby body shampoo (Meiji Holdings Co., Ltd.) was used as soap. The body was washed by hand and the face was washed with a disposable non-woven fabric (Hakujuji Co., Ltd.). Neonatal care was provided by nurses with sufficient experience and skill. No moisturizer was used after bathing.
Measurement and evaluation methods
1) Baseline characteristics
Data on mothers’ age and birth experience, the method of delivery and sex of the neonate, gestational age at birth, birth weight, somatotype, and family history of atopic dermatitis were collected.
2) Measurement environment
At both facilities A and B, Measurements were performed at a location in the newborn nursery that was maintained at a room temperature of 25℃±2℃ and humidity of 50%±10% and was not exposed to direct sunlight or affected by air conditioning. The measurements (Neonatal Behavioral Assessment Scale [NBAS, states 1 and 2]) were performed with the child at rest after the child was acclimated to the measurement environment for 30 minutes. For infants who were bathed, measurements were performed after 2 hours had elapsed since bathing, when the infants were most rested (falling asleep)15.
3) Evaluation of skin condition
The skin condition of neonates was evaluated and compared with respect to (1) physiological findings, (2) clinical skin findings, and (3) potential inflammatory responses in skin tissue as assessed by skin blotting. Measurements were performed at five sites on the neonate: the forehead (center), cheek (right), chest (center), arm (medial aspect of the right forearm), and buttock (right gluteal area).
4) Evaluation of physiological findings
Transepidermal water loss (TEWL) and epidermal pH were measured daily from 0 (postpartum) to 5 days of age. The measurements were repeated three times at each measurement site, and the mean values were used in the analysis. The VapoMeter (Delfin Technologies) was used to measure TEWL. The reference standard for TEWL varies in value by age and body site16, with higher values representing lower permeability barrier function. The pH measurements were performed using the Skin Check HI98109 pH tester (Hanna Instruments). A weakly acidic epidermal pH of approximately 5.0±0.5 (reference standard) indicates healthy skin and elevation of pH caused by disturbance in the stratum corneum is known to be harmful to barrier homeostasis17.
5) Evaluation of clinical skin findings
The evaluation of early neonatal skin condition is challenging. In this study, skin condition was evaluated in terms of inflammatory changes consisting of roughness, infiltration, and/or scaling (Supplementary Fig. 1). The lesions of diaper rash (Supplementary Fig. 2) were excluded in the evaluation of the skin condition of the buttock and the incidence of diaper rash was separately evaluated. Skin symptoms seen in the early neonatal period were evaluated daily from 0 (postpartum) to 5 days of age. Photos of the skin of 89 mm×127 mm in size were taken in five places using a single lens reflex camera (EOS Kiss X5). The camera was in P mode. The condition of the skin was evaluated based on imaging by a dermatologist who was a coinvestigator. The evaluator was blinded to information on the cleaning method and the subject. The incidence of inflammatory changes and diaper rash was determined.
6) Evaluation of inflammatory responses in skin tissue using skin blotting
Skin blotting, a method that can noninvasively evaluate potential inflammation in the skin18, was used to examine the protein expression of albumin and inflammatory cytokines (interleukin [IL]-6, tumor necrosis factor [TNF]-alpha) three times, at 1, 3, and 5 days of age.
The measurement protocol was as follows. First, a 1 cm×1 cm nitrocellulose membrane (Merck Millipore) moistened with physiological saline was placed on each of the five measurement sites for 10 minutes to collect protein. The nitrocellulose membrane was then stored at 4℃ until analysis. Next, the collected protein was immunostained using the SNAP i.d. 2.0 protein detection system (Merck Millipore). The nitrocellulose membrane was then treated for 10 minutes with a blocking agent (Blocking One; Nacalai Tesque). The proteins were reacted for 10 minutes with primary antibody (antialbumin antibody [A114AN; American Qualex], anti-IL-6 antibody [12153; Cell Signaling Technology], or anti-TNF-α antibody [sc-1350; Santa Cruz Biotechnology]) bonded to either ALP label (705-055-147; Jackson ImmunoResearch) or HRP label (711-035-152; Jackson ImmunoResearch). Chemiluminescence was achieved by addition of ALP substrate (Chemiluminescent AP Substrate; BioFX Laboratories) or HRP substrate (Luminata Forte; Merck Millipore), and the proteins were visualized using a high sensitivity chemiluminescence photography device (Bio-Rad ChemiDoc XRS+, Hi Sensitivity). Protein expression was quantified by image analysis using image processing software (ImageJ 1.50i; National Institutes of Health). Based on the expression levels, qualitative assessments of either “expressed” or “not expressed” were established using cutoff values calculated in a previous study (IL-6=2.77 µg, TNF-α=8.15 µg)19. In this experiment, samples from the cheek and chest were assessed to exclude the influence of vernix caseosa, which is abundant on other body sites, as much as possible.
Ethics approval and consent to participate
This study was carried out with the approval of the research ethics committee at Oita University of Nursing and Health Sciences (approval No. 1058).
Statistical analysis
Baseline characteristics between the bath and DT groups were compared using the t-test and chi-squared test. The daily differences in TEWL and pH between the bath and DT groups were examined with the t-test and Bonferroni correction. The difference in TEWL between day 1 and other days and the difference in pH between day 0 and other days were compared with the t-test and Bonferroni correction for each group. The incidence of skin symptoms and the level of expression of inflammatory cytokines at each time point were compared between the bath and DT groups with the chi-squared test and Bonferroni correction. This study was designed as an exploratory research so no hypothesis test was planned before statistical analysis. Analysis was performed using SPSS version 21.0 (IBM Corp.) and R statistical package, version 3.5.2 (R Core Team, December 2018; www.r-
RESULTS
Attributes of mothers and infants and the measurement environment
Study consents were obtained from 96 pregnant females with a normal antenatal course at the two institutions (48 female each). Of these, 85 females (bath group, 39 subjects; DT group, 46 subjects) had normal term deliveries (37 to <42 weeks). After the exclusion of five females whose child was admitted to the neonatal intensive care unit due to a respiratory disorder or for phototherapy for jaundice, 80 subjects (bath group, 36 subjects; DT group, 44 subjects) with a normal clinical course throughout the period examined were included in the analysis (valid data rate, 94.1%). A flow chart showing the process of enrollment, exclusion, and analysis is shown in Fig. 1.
Fig. 1
Diagram of the study flow.
The attributes of the mothers and infants in the study and measurement environment are shown in Table 1. Differences were seen between the bath and DT groups in the mean maternal age and mean infant birth weight. However, maternal age and infant birth weight at both facilities were comparable with the national figures (mean maternal age at delivery: first childbirth, 30.7 years; parous, 33.6 years; birth weight: 3,000 g)20. Therefore, we determined that the difference was not clinically meaningful. There was no significant difference between the two facilities with respect to the temperature or humidity of the measurement environment.
Table 1
Attributes of subject mothers and infants
Physiological findings of TEWL and skin pH
Areas of TEWL at birth (mean±standard deviation; g/m2/h) were the forehead (bath: 8.25±2.70, DT: 10.97±8.04), cheek (bath: 8.01±1.70, DT: 9.52±6.73), chest (bath: 8.01±2.67, DT: 8.23±5.72), arm (bath: 7.42±1.84, DT: 9.88±6.19), and buttock (bath: 10.09±2.06, DT: 9.03±4.97). On the first postnatal day, areas of TEWL were respectively found on the forehead (bath: 6.17±1.35, DT: 7.39±4.27), cheek (bath: 7.46±2.26, DT: 7.50±4.07), chest (bath: 6.97±1.15, DT: 6.29±3.37), arm (bath: 6.16±1.35, DT: 5.68±2.85), and buttock (bath: 9.19±2.04, DT: 7.42±3.90). All areas (forehead, cheek, chest, arm, and buttock) showed a decrease compared to birth in both the bath and DT groups. In the second half of the measurement period, TEWL tended to be higher in the bath group (9.43±2.51 to 10.72±2.79) than in the DT group (6.70±3.74 to 7.77±3.65), especially on the buttock (Fig. 2).
Fig. 2
Comparison of chronological changes in TEWL between the DT group (n=44) and Bath group (n=36). The graphs show the sample mean and 95% confidence interval of TEWL values measured at five sites (forehead, cheek, chest, arm, buttocks) from age 0 days to 5 days. The error bars show the 95% confidence interval. *p<0.05 vs. bath group; †p<0.05 vs. bath group on day 1; ‡p<0.05 vs. DT group on day 1. DT: dry technique, TEWL: transepidermal water loss.
Skin pH (mean±standard deviation) was highest immediately after delivery for all sites: forehead (bath: 6.50±0.73, DT: 6.48±0.83), cheek (bath: 6.50±0.77, DT: 6.54±0.84), chest (bath: 6.60±0.60, DT: 6.57±0.85), arm (bath 6.67±0.68, DT: 6.65±0.82), and buttock (bath: 6.51±0.52, DT: 6.39±0.67). Thereafter, through the first postnatal day, pH was higher on the forehead (bath: 6.31±0.58, DT: 5.87±0.53), cheek (bath: 6.13±0.47, DT: 5.57±0.58), chest (bath: 6.38±0.49, DT: 6.04±0.55), arm (bath: 6.49±0.57, DT: 6.02±0.52) and buttock (bath: 6.29±0.33, DT: 5.65±0.41) in both groups. In particular, the rate of change in skin pH in the DT group was significantly lower on the forehead (–0.6, confidence interval [CI]: –0.9 to –0.4), cheek (–1.0, CI: –1.3 to –0.7), chest (–0.5, CI: –0.8 to –0.2), arm (–0.6, CI: –0.9 to –0.3) and buttock (–0.7, CI: –0.9 to –0.5) (p<0.001, p<0.001, p<0.01, p<0.001, p<0.001, respectively). Skin pH values after 1 day of age were significantly higher in the bath group than in the DT group at all sites (Fig. 3).
Fig. 3
Comparison of chronological changes in skin pH between the DT group (n=44) and bath group (n=36). The graphs show the sample mean and 95% confidence interval of skin pH values measured at five sites (forehead, cheek, chest, arm, buttocks) from age 0 days to 5 days. The error bars show the 95% confidence interval. *p<0.05 vs. bath group; †p<0.05 vs. bath group on day 0; ‡p<0.05 vs. DT group on day 0. DT: dry technique.
Clinical skin findings
In the bath group, the incidence of inflammatory findings increased with age at all four sites except for the buttock. On the other hand, inflammatory change was limited in the DT group (Fig. 4A). No gross inflammatory findings were found on the buttocks in both groups, but the incidence of diaper rash tended to be higher in the bath group (Fig. 4).
Fig. 4
Comparison of the occurrence of gross skin findings between the DT group (n=44) and Bath group (n=36). (A) The graph shows the percent occurrence of skin inflammatory findings observed in the DT and bath groups at five sites (forehead, cheek, chest, arm, buttocks) from age 0 days to 5 days. (B) The graph shows the percent occurrence of diaper rash observed in the DT and Bath groups from age 0 days to 5 days. *p<0.05 vs. DT group. DT: dry technique.
Inflammatory cytokine expression
Albumin was detected on the skin of all neonates in both groups. IL-6 expression in the skin of the cheek was comparable between the two groups, while IL-6 expression in the skin of the chest was significantly higher in the bath group (day 1: 44.0%, day 5: 33.3%) than in the DT group (day 1: 11.4%, day 5: 0%) (p<0.01, p<0.01, respectively) (Fig. 5A). The incidence of TNF-α expression was significantly higher in the DT group (day 1: 38.9%, day 3: 28.9%, day 5: 30.0%) and the bath group (day 1: 84.0%, day 3: 92.6%, day 5: 72.2%) in the cheek and in the DT group (day 1: 40.0%, day 3: 18.4%, day 5: 25.0%) and the bath group (days 1, 3, and 5: all 100%), in the chest and TNF-α expression was significantly higher in the bath group at both examination sites on days 1, 3, and 5 (cheek: p<0.001, p<0.001, p<0.01, respectively; chest: all p<0.001) (Fig. 5B).
Fig. 5
Comparison of IL-6 and TNF-α expression rate between the DT group (n=44) and the bath group (n=36). (A) The graphs show the expression rate (%) of IL-6 in the DT group and bath group measured at five sites (cheek, chest) at age 1, 3, and 5 days. (B) The graphs show the expression rate (%) of TNF-α in the DT group and bath group measured at five sites (cheek, chest) at age 1, 3, and 5 days. DT: dry technique, IL-6: interleukin-6, TNF-α: tumor necrosis factor-alpha. *p<0.05 vs. DT group.
DISCUSSION
To investigate which cleaning method maintains skin health in the early neonatal period, skin physiological parameters (i.e., TEWL and pH), clinical findings, and inflammatory markers were examined in the bath and DT groups.
The greatest reduction in TEWL, an indicator of barrier permeability, occurred during the period from birth to 1 day of age, with marked decreases seen at all measurement sites in both the bath and DT groups. This may reflect the rapid maturation of the stratum corneum after birth, and increased barrier impermeability as a result of the increased lamellar granule secretion, keratinocyte, and facilitated keratinization that occur when the stratum corneum is exposed to an external environment with low humidity21. It has been reported that skin pH declines steeply during the first postnatal week16, 22, which reflects the rapid maturation of the stratum corneum after birth, as was seen in the present study.
TEWL remained nearly unchanged from 1 day of age onward. The TEWL values in this study were consistent with previous studies of full-term infants23, 24, 25, 26. However, the change in TEWL differed according to the cleaning method used. TEWL of buttock skin was lower in the DT group than in the bath group from 1 day of age onward and from 4 days of age onward at other sites, indicating better permeability barrier function in the DT group and/or induction of inflammatory reaction in the bath group. Accordingly, the skin surface pH values in the DT group were lower than those in the bath group. In addition, the difference in skin surface pH between the bath and DT groups was detected earlier than the difference in TEWL. This suggests that skin surface pH might be more sensitive than TEWL in detecting disturbance in the skin condition and that maintenance of skin pH might be important for skin health. In fact, skin surface pH is considered key in maintaining the skin in a good condition27.
In line with the results of the physiological parameters, clinical findings revealed that an inflammatory reaction arose more frequently in the bath group than in the DT group. Although there were significant differences in TEWL and skin surface pH of buttock skin in both the bath and DT groups, no inflammatory reaction was observed on the buttock, except for diaper rash. This suggests that physiological parameters might be more sensitive in detecting skin disturbance than clinical findings.
IL-6 plays a role in cell proliferation28. TNF-α is induced by external stimulation or early inflammation and is responsible for barrier repair29, 30, 31. Consistent with the physiological parameters and clinical findings mentioned above, elevation of IL-6 and TNF-α levels was more frequently detected in the bath group than in the DT group, except for IL-6 levels in cheek skin. Although the reason for similar IL-6 levels in cheek skin is unclear, it is possible that cheek skin might be exposed to more external stimuli than chest skin.
Taken together, these results suggest that bathing might be harmful to the skin of early neonates compared with the dry technique. Bathing leads to repeated physical and chemical stimulation of the immature skin32, 33. Although the role of vernix caseosa in the maintenance of skin health remains unclear, the removal of vernix caseosa with bathing, which covers the skin surface and facilitates colonization by normal bacteria, might be involved in the disturbance of skin condition in the bath group.
In conclusion, DT reduces the likelihood of inflammatory responses by minimizing external stimuli such as physical and chemical stimulation. In addition, it promotes maturation of skin barrier function by preserving the vernix caseosa that protects early neonatal skin. It is therefore a means of cleaning that can preserve the skin health of neonates in the 5 days after birth.
In view of ethical considerations, the study was conducted at two facilities that used different cleaning methods in order to avoid any inequities that may arise if infants were cleaned in the same institution. Care was taken to minimize differences in the measurement environment. However, we could not ensure uniformity of all background factors such as the areas in which the facilities were located, maternal transport, and hospitalization of the infants. In the future, it will be necessary to accumulate scientific evidence by investigating parameters such as biomarkers and to verify the efficacy of cleaning in a long-term follow-up study.
SUPPLEMENTARY MATERIALS
Supplementary data can be found via http://anndermatol.org/src/sm/ad-
Representative clinical findings exhibiting inflammatory changes in each site.Supplementary Fig. 1
Representative clinical findings of diaper rash.Supplementary Fig. 2
CONFLICTS OF INTEREST:The authors declare that they have no competing interests.
FUNDING SOURCE:This work was supported by Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS), a grant Number 16K20799. The funders did not have any role in the study design, data collection, analysis, and interpretation of data or in writing the manuscript.
ACKNOWLEDGMENT
We thank all the parents and newborns for their participation and the staff of Katsushika Maternity Hospital for their cooperation. The patients in this manuscript have given written informed consent to publication of their case details including photography.
DATA SHARING STATEMENT
Research data are not shared.
References
-
Dębińska A, Sozańska B. Epicutaneous sensitization and food allergy: preventive strategies targeting skin barrier repair-facts and challenges. Nutrients 2023;15:1070
-
-
Okuda M, Yoshiike T. [Correlation between epidermal barrier function and skin cleansing methods]. Jpn J Dermatol 2000;110:2115–2122.Japanese.
-
-
American Academy of Pediatrics Committee on Fetus and Newborn. Skin care of newborns. Pediatrics 1974;54:682–683.
-
-
Higuchi S, Notsu A, Umeno Y, Abe M. [Current trends and issues in early neonatal hygiene and skin care in Japan]. Jpn J Matern Health 2017;58:91–99.Japanese.
-
-
Brazelton TB, Nugent JK. In: Neonatal behavioral assessment scale. 3rd ed. Cambridge University Press; 1995.
-
-
Higuchi S, Yoshida S, Minematsu T, Ichinose T. Detection of inflammatory cytokines by skin blotting as an objective measure of neonatal skin problems. J Nurs Sci Eng 2019;6:33–40.
-
-
Government of Japan, Cabinet Office. Trends in the mean age of first marriage and mean age of mothers by live birth order [Internet]. Government of Japan, Cabinet Office; 2016 May 24; [cited 2022 Apr 18].Available from: https://www8.cao.go.jp/shoushi/shoushika/whitepaper/measures/english/w-
2016/pdf/part1_ 1- 1.pdf .
-
-
Kawashima M. In: [People who suffer from skin trouble]. Japan Broadcast Publishing Co., Ltd; 2002. pp. 62-65.Japanese.
-
-
Okada A. [Evidence of clean care - bathing/cleaning -]. J Clin Nurs 2002;28:959–970.Japanese.
-
MeSH Terms
Figures
1 / 5
Tables
1 / 1
