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Journal of Human Growth and Development

versão impressa ISSN 0104-1282versão On-line ISSN 2175-3598

Rev. bras. crescimento desenvolv. hum. vol.23 no.2 São Paulo  2013

 

ORIGINAL RESEARCH

 

Cultural aspects of offering pacifier to children

 

 

Elâine Cristina Vargas DadaltoI; Edinete Maria RosaII

IDoutoranda em Psicologia pela Universidade Federal do Espírito Santo (UFES), Mestre em Odontopediatria pela UFRJ e Professora de Odontopediatria da UFES
IIDoutora em Psicologia Social pela USP, Professora do Departamento de Psicologia Social e do Desenvolvimento e do Programa de Pós-Graduação em Psicologia da UFES

Correspondence

 

 


ABSTRACT

INTRODUCTION: A cultural object or phenomenon expresses the historical experience of several previous generations. The use of pacifiers by children has led to uncle debates from the biological point of view. However, the pacifier's representation as a social object, product of culture, should also be analyzed.
OBJECTIVE: to verify aspects related to the cultural appropriation in the studies analyzing pacifier sucking habits.
METHOD: The study consulted databases MEDLINE, LILACS, SciELO, Cochrane Library, and Portal CAPES, and selected articles issued between 2002 and 2011.
RESULTS: Twenty-six (26) studies on pacifier sucking habits regarding cultural aspects have been found. The use of the pacifier has been very frequent, even when mothers had been advised by health care professionals not to offer pacifiers to infants.
CONCLUSION: The results of the studies investigated highlighted the cultural appropriation process when the use of the pacifier by children is analyzed.

Key words: pacifiers; culture; habits; sucking behavior; child.


 

 

INTRODUCTION

Culture is an essential part of each person's and each society's makeup. It composes the human structure, a product of a developmental process that is deeply grounded in the connections between individual and social history. The potential for complex operations already exists in the earlier stages of individual development. However, there are many transitional psychological systems between what was biologically given and culturally acquired. The use of instruments and the human speech alone place childhood in the pre-history of cultural development. Therefore, every function of development first appears at the social level, and then at the individual level1.

The relationship between psychological subject and cultural context in Vygotsky's theory is not a static system to which the individual is submitted. On the contrary, each individual is absolutely unique and, through their psychological processes, they are involved in a constant process of recreation and reinterpretation of information, concepts and meaning, thus recreating their own culture2.

The cultural setting allows us to accumulate information that is reflected in beliefs, practices and rituals, ranging from mere demonstration of certain performances to directed formal instructions. Among other things, culture exempts individuals from learning by practicing, trying all over again at every generation and, at the same time, it allows individuals to add new knowledge derived from their own experience3.

Aptitudes and specifically human characteristics are acquired along life through a process of cultural appropriation created by previous generations. In the case of objects, in order for their appropriation to take place, it is necessary to develop an activity that reproduces, through its form, essential traces of the activity accumulated in the object. An instrument, for example, is a product of material culture, with a particular form, and that has features of human creation. Thus, it is at the same time a social object4.

Cultural appropriation is a process that mediates the historical process of human genus formation and the process of forming each individual into a human being. Within the meaning of an object or cultural phenomenon, the historical experience of several generations is accumulated and, throughout this history, the object undergoes transformations and improvements that are required by social activity. By appropriating a cultural product, individuals relate to social history, because cultural products are syntheses of human activity5.

The relationship between human nature and culture allows the accumulation of information, which is reflected in beliefs and practices. Because the parental belief systems are directly related to type of care provided the the child, they have emerged as a significant field of study for understanding human development and as the scientific basis for promoting health care, education and social welfare6.

The use of pacifiers by children is a theme that has caused many debate in the health care literature, from a biological point of view. However, the pacifier's representation as a social object, product of culture, should also be analyzed in-depth. Therefore, this study aims at verifying aspects related to the cultural appropriation of pacifier sucking habits in infants and children.

 

METHOD

In order to gather data on the scientific productions available in articles about the use of pacifiers by children, and to verify the how cultural aspects are approached, the study consulted the data bases MEDLINE - International Literature on Health Sciences; LILACS - Latin-American and Caribbean Literature on Health Sciences; SciELO - Scientific Electronic Library Online; Cochrane Library and Portal for Capes (Coordination for the Improvement of Higher Education Personnel) Journals, taking into account the period between 2002 and 2011.

Five hundred and five (505) reference records were obtained under the keyword "pacifiers". During the analyses of the respective abstracts, we realized that many of the studies concerned the material to manufacture pacifiers; disinfecting pacifiers; specific biological aspects such as sudden infant death; interference in breast feeding; and use of pacifiers to relieve pain after small surgical procedures, among others. As inclusion criterion for the reference to fit the study category of "pacifier sucking habits", we added the keywords "culture", "habits", "sucking behavior" and "child". Then, 45 studies were selected. Each article was analyzed separately to verify the presence of aspects related to culture.

 

RESULTS

Our investigation found 26 scientific publications containing data about cultural aspects regarding pacifier sucking habits, published between 2002 and 2011. Among these articles, we analyzed studies using quantitative methodology and qualitative approach, including articles that did not concern the use of pacifiers specifically, but analyzed cultural aspects related to this object. These studies are described in the topic below and listed in Tables 1 and 2.

Historical and current context in which pacifiers are used

The precursor of the modern pacifier emerged in the 19th century and it was like a cork made of horn or wood with an adapted rubber nipple, created to substitute the old tradition of giving the child linen bags to suck. These bags were filled with oatmeal porridge, bread crumbs or sugar, and were often dipped in beer or liquor. After the Second World War, mass production caused the widespread use of the plastic product7. Nowadays, pacifiers are generalized and seem to have no limit for variations: Customized, gender-specific, that glow in the dark, with cartoon characters, among others8. In most cases, they are purchased by the mothers, because of easy access to drugstores near their homes9.

The high percentage of pacifier use may explain the relatives' persistence in the infant "taking" the pacifier, which, added to its unrestricted use, may lead to functional alterations that interfere in the process of growth and facial development10.

In order to exemplify the high prevalence of pacifier use in western cultures, we can refer to the study by Cotrim, Venancio and Escuder11 (State of São Paulo, Brazil). Among the 22,188 children of up to four months old assessed by the authors, 61.3% had used the pacifier in the past 24 hours. Çaglar et al.12 consider the pacifier to be very popular in most study countries (Brazil, Mexico, Norway, Sweden, Turkey and the United States) except for Niigata, in Japan, where the prevalence was zero. Lindsten and Larsson13 compared two generations of Swedish children and observed that the pacifier sucking habit wes more common among the children born between 1995 and 1997 (72%) than among those born in 1967 (55%).

On the other hand, in an indigenous community on the Central Brazilian Amazon, the Waimiri Atroari Indians preserved their traditional life style and remained free from habits such as smoking, alcohol drinking and pacifier sucking14. Likewise, in a study carried out in the United Arab Emirates, other beliefs and cultural habits determined mothers' behavior to calm infants down. The most common soothing method was breastfeeding, followed by holding and carrying the infant, allowing the infant to suck his finger, giving herbal tea and night bottle, swaddling infant, using stripes, giving baths and massaging. Around 92% of mothers preferred not to use pacifiers. The main reason was to allow the children to have healthy teeth development15.

Among Iranian girls, pacifier prevalence was low and limited to the first two years of life compared to other populations and cultures. However, the prevalence of thumb sucking was very similar to that in other studies. These results suggest that the etiology of thumb sucking remains the same, regardless of cultural diversity, whereas the difference in the prevalence of pacifier sucking among populations and cultures requires additional investigation into the etiology of this habit16.

Ritualization in the offer and removal of the pacifier

Geib17 discusses the cultural influence on the biology of sleep as a guide to parental decisions about the sleeping position and method, the offer of food and about sharing or not their bed. These decisions emerge from sleeping habits during childhood, including amount of sleep, length of infant crying, mothers' waking up, as well as the use of pacifiers or objects.

In order to facilitate the process that gradually integrates individuals within their cultural complexity, adults create a ritual to differentiate the stages of life, such as introducing the pacifier during early childhood and removing it at a given moment. In Nordic countries, the age of three is considered the deadline to remove the pacifier because the cultural ideology itself demands it for the sake of children's autonomy. It is when the child begins its pre-school stage and parents begin to worry about having taught this bad habit to which the child is now addicted. Therefore, the use of pacifiers causes mixed feelings and depends on concepts of childhood created by the culture. Rituals create new and short stages of life to compensate for ambivalence, to establish new relations and transfer responsibility from the individual to the collective sphere7.

In order to remove the pacifier and/or thumb sucking habit, the most frequent reports in the study families observed by Martins et al.18 (Mutum-MG) involved dialoguing with the children, exchanging it for gifts and in creasing awareness about the effects of those habits. More radical methods such throwing the pacifier out or spreading bitter substances on the finger or pacifier were the least frequent reports. A small percentage of children interrupted the habit spontaneously.

Cultural aspects regarding mothers' previous concepts and experiences related to the use of pacifiers

Concerning primiparas' intentions to acquire and offer pacifiers to their infants, Melo et al.19 verified that 88.1% of them had already bought or been given this object, and 60.8% responded they were going to use it. Of these, 59.8% responded they were going to start using the pacifier when they arrived at home, and 8% of the newborns were already using it at the maternity hospital.

Aliboni, Alfie and Pastrana20 observed that children whose fathers or mothers had used pacifiers as children had a more statistically significant chance of using pacifiers, too. If the fathers had used pacifiers, the children were 4.2 times more likely to use the object, whereas if the mothers had used pacifiers during childhood, the risk was 5.25 times greater.

The pacifier was the most prevalent habit in the study by Serra-Negra et al.21, both among mothers in their childhood (46.6%) and the children nowadays (65.4%). In 78.9% of the cases of involving pacifier sucking by mothers, there was a statistically significant coincidence with their children's present habit. The risk of the child also using a pacifier was 3.4 times higher than that for children of mothers who did not have this habit.

By interacting with the newborn, the mother's conception of pacifiers can change. Between the initial response as to whether or not the mother intended to give the infant a pacifier and the follow up question as to whether the mothers had actually introduced the pacifier or not in the study by Pansy et al.22, around one third of them had changed their opinion an this subject, both because of the infant's refusal to take a pacifier and also because of the need to calm the infant down.

Cultural characterization õf mothers' decision about offering a pacifier

In order to understand and describe the elements that make up a mother's decision to offer the child a pacifier, a study based on the assumptions of the Social Representation Theory was carried out by Sertório and Silva23 (São Paulo, Brazil). The leading question in the interviews was: "What led you to giving your child a pacifier?" The results presented three main ideas: 1) the pacifier symbolizes the child; 2) the pacifier is soothing to the child and helpful to the mother; 3) The use of pacifier is passed down from generation to generation. The authors concluded that there is a social representation concerning pacifiers that can be used as a causal explanation of the mother's behavior and attitude while offering this object to the child, as anticipating providing comfort to the child. The mother's ability to soothe her child is an element that can qualify her in her identity as a mother.

The pacifier is used with great frequency, even in populations advised to avoid its use, such as among infants born at a hospital identified as baby-friendly. In these places, mothers are recommended not to introduce pacifiers or milk bottles to infants. Otherwise they will have a higher risk of weaning before six months and thus not receiving the benefits of breastfeeding, compared to those who do not use these artificial nipples. In a population with these characteristics, the use of pacifiers was tried by at least 87.8% of the children in the first month of life, and 61.6% used it at one month old24.

In the study by Pinto et al.25 (Recife, PE, Brazil), which consisted of a pilot study that interviewed 40 mothers of children aged between zero and four years old, 82% of those who responded that using a pacifier is harmful to an infant's health and teeth allowed their children to use it.

Even though the mothers had been advised during pregnancy not to offer a pacifier to their children, 55% of the infants between two and seven months old used the pacifier when visited at home as part of the study by Simioni, Comiotto and Rêgo26. These authors also report that the main reason was to stop crying, since this helps the child calm down. One of the mothers said she did not want to give the newborn a pacifier because of what she had heard during the lecture, but the infant was using it because the father had insisted. "I gave it because her father said that when she grows up a little and is at home sick and crying, she will have the pacifier to console her. He kept saying this."

The study by Santos Neto et al.27 (Vitória, ES, Brazil) about the factors associated with the occurrence of mouth breathing was carried out while monitoring the visit of a public health agent to residences of mothers and their newborn, at every three and six months. During these visits, the mothers were advised about caring for newborns, including about sucking habits. Even so, the prevalence of pacifier sucking habits ranged between 30 and 50% during the first two years of life.

The results of Marques, Cotta and Araújo28 (Cajuri, MG, Brazil) suggest that the mothers had been advised about the inappropriateness of pacifiers, because they said it was not good to give it to children, but they opted for using it so as to calm their infants down, entertain them and thus allow mothers to do other activities. The social representation identified was that "the pacifier is helpful to mothers". One thing observed during a field investigation refers to the frustration of mothers who tried to introduce the pacifier but were bad met by the child. These mothers believed "they had lost an important help" with taking care of the infant.

In a hospital setting approach with puerperal mothers about high-risk newborn care, one of respondents in the study by Iserhard et al.29 said that she did not agree with the recommendation of not using the pacifier and that, back home, she would give it to the infant anyway because the child gets calmer - something she had learned by mothering another child and from her experience as a preschool teacher.

In the study by Fófano et al.30 61.6% of the mothers reported having received some kind of professional advice about the consequences of using a pacifier but, even so, there was no significant statistical correlation between offering a pacifier to children and not doing so. It is worth highlighting that the prevalence of pacifier use in this study was high (85.8%).

The influence of culture in health care professional advice about offering pacifiers

The influence of culture can also be observed among health care professionals. A study carried out of these professionals who were also mothers of children under 5 years of age and who worked in the Family Health Care Program (Recife, PE, Brazil) showed that their difficulties in continuing exclusive breast feeding and the frequent practice of introducing artificial nipples, including pacifiers, are consistent with the brazilian reality, even though this is a group of women who are responsible for the community health counseling31.

The offering of pacifiers causes controversy among health care professionals, who can recommend or discourage its use based on their own experience and not only on scientific evidence. This has led some representative institutions of health care professionals to plan recommendations as to the use of pacifiers, including the analysis that it is necessary to better understand the role of pacifiers and their probable interference from the biological point of view, as well as to study its differing effects in different cultures32.

In an assessment of the responses by health care professionals in England about the use of pacifiers, Whitmarsh8 observed that 55% of the professionals based their practice on concepts that could have been influenced by culture, society or the media, which suggests a discourse about using pacifiers that is dissaminated by the media. The arguments of specialists have been privileged and taken as "the truth", because in relevant studies, parents' points of view have been disregarded, which suppresses the main participants in this system. The author concludes by proposing the challenge of finding an alternative perception of the use of pacifiers-one that can be inserted into the context of the child's first years.

Thus, the pacifier as a cultural object, and its offer by adults and use by children as a cultural phenomenon have undergone transformations and improvement throughout the centuries, starting from the ancient traditions of giving fabric artifacts for infants to suck. The use of pacifiers has been very frequent in western countries9,11-13 and it has been reported by mothers as a habit that "every child has"21 and that "the pacifier symbolizes the child and its use is passed down from generation to generation". This has been associated with the social representation that the pacifier "is soothing to children"23,29 and "helpful to mothers"23,28. Many mothers buy or are given this object even before going to the maternity hospital19. These mothers intend to calm down their infants firenly believing that not offering a pacifier is a synonym of carelessness and lack of love.30

The results of the studies analyzed highlighted the process of cultural appropriation created by the previous generations when pacifier use is analy-zed7-13,17-31, as well as the influence of other cultural habits in regions where this object is not used, such as among the Amazon Indians14 and in the United Arab Emirates15. Some studies have shown that, even though mothers receive professional advice not to offer pacifiers to newborns because they interfere in breastfeeding, their use is very frequent24,26,29,30. Lindsten and Larsson13 comment that today's mothers in Sweden are well informed about breastfeeding, but modern life makes it difficult for the woman to follow traditional ways to raise infants, carrying them around all the time and allowing them to breastfeed whenever they want.

Therefore, this study verifies that mere transmission of information as an educational approach is not enough by itself to change behavioral patterns and habits that have a cultural background and are grounded in the customs of populations. Educational activities should start with capturing individual values and then trying to adequate actions to motivate individuals to act, while respecting their particularities26. In a broader sense, promotion of healthy behavior an the of basis educational activity is one of the targets of public health for improving health and quality of life33.

Mothers and family members should be warned about the need to establish the breastfe-eding and observe if the infant needs extra sucking, such as sucking the tongue or fingers, for example. Before offering a pacifier, caregivers should see if the crying is related to the need to suck or other reasons. If the family opts for introducing the pacifier, it should be made clear that limits have to be set in its use, mainly because of the consequences to the dental arch and other mouth functions such as breathing, swallowing, and speaking.

 

REFERENCES

1. Vygotsky LS. A formação social da mente. O desenvolvimento dos processos psicológicos superiores. 6 ed. São Paulo: Martins Fontes, 2000. p. 38-76.         [ Links ]

2. LaTaille Y de, Dantas H, Oliveira MK de. Três perguntas a Vygotskianos, Wallonianos e Piagetianos. In: LaTaille Y de, Dantas H, Oliveira MK de. Piaget, Vygotsky, Wallon: teorias psicogenéticas em discussão. São Paulo: Summus. 1992. p. 101-115.         [ Links ]

3. Bussab VSR, Ribeiro FL. Biologicamente cultural. In: Souza L, Freitas M de FQ de, Rodrigues MMP. Psicologia: reflexões (im)pertinentes. São Paulo: Casa do Psicólogo, 1998. p. 175-194.         [ Links ]

4. Leontiev A. O desenvolvimento do psiquismo. São Paulo: Centauro, 2004. p. 285-88.         [ Links ]

5. Duarte N. Formação do indivíduo, consciência e alienação: o ser humano na psicologia de A. N. Leontiev. 2004;24(62):44-63.         [ Links ]

6. Kobarg APR, Sachetti VAR, Vieira ML. Valores e crenças parentais: Reflexões teóricas. Rev Bras Crescimento Desenvolv Hum. 2006;16(2):96-102.         [ Links ]

7. Selmer-Olsen I. The pacifier: a story about comfort, rituals and aesthetification of childhood. Childhood. 2007;14(4):521-35.         [ Links ]

8. Whitmarsh J. The good, the bad and the pacifier: unsettling accounts of early years practice. J Early Child Res. 2008;6(2):145-62.         [ Links ]

9. De Carli ERB, Imparato JCP, Bussadori SK. Fatores que influenciam as mães no momento da escolha das chupetas. JBP J bras odontopediatr odontol bebê. 2002; 5(23):16-20.         [ Links ]

10. Praetzel JR, Saldanha MJ de Q, Pereira JE da S, Guimarães MB. Relação entre o tipo de aleitamento e o uso de chupeta. JBP J bras odontopediatr odontol bebê. 2002;5(25):235-240.         [ Links ]

11. Cotrim LC, Venancio SI, Escuder MML. Uso de chupeta e amamentação em crianças menores de quatro meses no estado de São Paulo. Rev bras saúde matern infant. 2002;2(3):245-252.         [ Links ]

12. Çaglar E, Larsson E, Andersson EM, Hauge MS, Ogaard B, Bishara S, Warren J, Noda T, Dolci GS. Feeding, artificial sucking habits, and malocclusions in 3-year-old girls in different regions of the world. J Dent Child. 2005; 72(1): 25-30.         [ Links ]

13. Lindsten R, Larsson E. Pacifier-sucking and breast-feeding: a comparison between the 1960s and the 1990s. J Dent Child. 2009;76(3):199-203.         [ Links ]

14. Santos PJ dos, Bessa CF, Aguiar MC de, Carmo MA do. Cross-sectional study of oral mucosal conditions among a central Amazonian Indian community, Brazil. J Oral Pathol Med. 2004;33(1):7-12.         [ Links ]

15. Abdulrazzaq YM, Al Kendi A, Nagelkerke N. Soothing methods used to calm a baby in an Arab country. Acta Paediatr. 2009; 98(2): 392-6.         [ Links ]

16. Jahanbin A, Mokhber N, Jabbarimani A. Association between sociodemographic factors and nutritive and non-nutritive sucking habits among Iranian girls. East Mediterr Health J. 2010;16(11):1143-7.         [ Links ]

17. Geib LTC. Moduladores dos hábitos de sono na infância. Rev Bras Enferm. 2007;60(5):564-8.         [ Links ]

18. Martins BS, Dadalto ECV, Gomes, AMM, Sanglard LF, Valle MAS do. Métodos usados para remoção dos hábitos de sucção de dedo e/ou chupeta em crianças do município de Mutum-MG. Rev Bras Pesq Saúde. 2010;12(4):19-25.         [ Links ]

19. Melo AM de CA, Cabral PC, Albino E, Moura LMD, Menezes AEB de, Wanderley LG. Conhecimentos e atitudes sobre aleitamento materno em primíparas da cidade do Recife, Pernambuco. Rev bras saúde matern infant. 2002; 2(2): 137-42.         [ Links ]

20. Aliboni VG, Alfie JD, Pastrana SC. Uso del chupete: hallazgos preliminares. Arch argent pediatr. 2002;100(2):114-119.         [ Links ]

21. Serra-Negra JMC, Vilela LC, Rosa AR, Andrade ELSP, Paiva SM, Pordeus IA. Hábitos bucais deletérios: os filhos imitam as mães na adoção destes hábitos? Rev odonto ciênc. 2006;21(52):146-152.         [ Links ]

22. Pansy J, Zotter H, Sauseng W, Schneuber S, Lang U, Kerbl R. Pacifier use: what makes mothers change their mind? Acta Paediatr. 2008;97(7):968-71.         [ Links ]

23. Sertório SCM, Silva IA. As faces simbólica e utilitária da chupeta na visão de mães. Rev Saúde Pública. 2005;39(2):156-62.         [ Links ]

24. Soares ME, Giugliani ER, Salgado AC, Oliveira AP de, Aguiar PR de. Uso de chupeta e sua relação com o desmame precoce em população de crianças nascidas em Hospital Amigo da Criança. J Pediatr (Rio J). 2003; 79(4): 309-16.         [ Links ]

25. Pinto MCGL, Melo GFB de, Colares V, Katz CRT. Fatores sócio-econômico-culturais relacionados ao uso da chupeta em crianças de zero a quatro anos da cidade do Recife-PE. Arq odontol. 2003;39(4):285-296.         [ Links ]

26. Simioni LRG, Comiotto MS, RêgoDM. Percepções maternas sobre a saúde bucal de bebês: da informação à ação. RPG Rev Pós Grad. 2005;12(2):167-73.         [ Links ]

27. Santos Neto ET dos, Barbosa RW, Oliveira AE, Zandonade E. Fatores associados ao surgimento da respiração bucal nos primeiros meses do desenvolvimento infantil. Rev Bras Crescimento Desenvolv Hum. 2009; 19(2): 237-248.         [ Links ]

28. Marques ES, Cotta RMM, Araújo RMA. Representações sociais de mulheres que amamentam sobre a amamentação e o uso de chupeta. Rev Bras Enferm. 2009;62(4):562-9.         [ Links ]

29. Iserhard ARM, Budó M de LD, Neves ET, Badke MR. Práticas culturais de cuidados de mulheres mães de recém-nascidos de risco do sul do Brasil. Esc Anna Nery Rev Enferm. 2009; 13(1):116-22.         [ Links ]

30. Fófano C de SN, Mialhe FL, Silva RP da, Brum SC. Conhecimentos, atitudes e práticas maternas em relação ao uso da chupeta. Pesqui bras odontopediatria clín. intergr. 2009; 9(1): 119-2.         [ Links ]

31. Caminha M de FC, Serva VB, Anjos MMR dos, Brito RB de S, Lins MM, Batista Filho M. Aleitamento materno exclusivo entre profissionais de um Programa de Saúde da Família. Cien. Saúde Colet. 2011;16(4):2245-50.         [ Links ]

32. Lozano de La Torre MJ, Alonso CR, Aguilar MT, Maldonado JÁ, Ansótegui JÁ, Segura AS, Papí AG, Gómez MD, Moya AJ, Rivera LL, Velillas JJ, Martín-Calama Valero J, Morales MM, Talayero JM, Escós MD. Uso del chupete y lactancia materna. An Pediatr (Barc). 2011; 74(4): 271 e 1-271 e 5.         [ Links ]

33. Atrash HK, Carpentier R. The evolving role of public health in the delivery of health care. J Hum Growth Dev. 2012; 396-9.         [ Links ]

 

 

 Correspondence to:
elainedadalto@gmail.com

Manuscript submitted Mar 22 2012
Accepted for publication Feb 12 2013