JPediatr(RioJ).2016;92(3):217---219
www.jped.com.br
EDITORIAL
Social
and
biological
determinants
of
growth
and
development
in
underprivileged
societies
夽
,
夽夽
Determinantes
sociais
e
biológicos
do
crescimento
e
desenvolvimento
em
sociedades
menos
favorecidas
Mijna
Hadders-Algra
BeatrixChildren’sHospital,UniversityMedicalCenterGroningen,Groningen,TheNetherlands
The stimulating study by da Rocha Neves et al. (in this issue)1addressestheroleofsocialandbiologicalfactorsin
growthand developmentof youngchildren in a disadvan-tagedsociety.Theauthorsassessedagroupof92children, aged 24---36 months, whoin 2011 attended the municipal earlychildhoodeducationnetworkinatownintheValedo Jequitinhonharegion.ThisregioninthesoutheastofBrazil isconsideredeconomicallyunderprivileged.Thestudywas restricted to children with typical development, which meant that the children did not suffer from an evident congenital or acquired disability. Growth was assessedby meansofstandardanthropometrics,withafocuson height-for-age, a valid tool to assess childhood malnutrition.2
DevelopmentwasmeasuredwiththeBayleyScalesofInfant and Toddler Development (BSITD-III),3 the gold standard
to measure developmental outcome at early age. The cognitive score and the expressive language scores were usedasoutcome parameters. Biologicalrisk was assessed byafewperinatalfactors,suchasgestationalageatbirth, birthweight,pregnancycomplications,andthenumberof prenatal consultations, and a few childhood parameters, includingbreastfeeding,thepresenceof chronicdiseases,
DOIoforiginalarticle:
http://dx.doi.org/10.1016/j.jped.2015.08.007 夽
Pleasecitethisarticleas:Hadders-AlgraM.Socialand
biolog-icaldeterminants ofgrowthand developmentin underprivileged
societies.JPediatr(RioJ).2016;92:217---9.
夽夽
SeepaperbydaRochaNevesetal.inpages241---50.
E-mail:m.hadders-algra@umcg.nl
infectious diseases, and hospital admissions. The social environment was documented extensively, not only by means of parental level of education, the number of siblings,and the numberof people in the household,but also with standardized questionnaires to assess (a) the economicsituation(withthequestionnaireoftheBrazilian AssociationofResearchCompanies[Associac¸ãoBrasileirade EmpresasdePesquisa]);(b) thequalityofearly childhood education (with the Infant/Toddler Environment Rating Scale --- Revised); (c) the quality of the home environ-ment (with the Home Observation for Measurement of the Environment (HOME) Inventory); and (d) the quality of the neighborhood (with a self-developed question-naire including questions on accessibility and quality of services).
The results confirmed that the children had a socially disadvantagedbackground.Thiswasreflectedbythefinding thatabout90%ofthefathershadnotcompletedhighschool, and that approximately half of the children did not live withbothparents.Thelargemajorityofchildrenwereborn atterm(94%),withoutsignsofsevereintrauterinegrowth restriction. Almost half of the children had had chronic and/or infectious diseases in thethree months preceding thestudy.
Impairedgrowth,definedasheight-for-agefallingbelow twostandarddeviationsofthenorm,occurredin15%of chil-dren.Multivariableanalysisindicated thatstuntedgrowth wasassociatedwithbirthweightandthenumberofprenatal consultations.Noneofthemanysocialfactorscontributed to impaired growth. This suggests that early childhood growthislargelydeterminedbythequalityofprenatallife.
http://dx.doi.org/10.1016/j.jped.2016.02.001
0021-7557/©2016SociedadeBrasileiradePediatria.PublishedbyElsevierEditoraLtda.ThisisanopenaccessarticleundertheCCBY-NC-ND
218 Hadders-AlgraM
Thechild’sprenatalcondition,inturn,isbasedonacomplex interactionofbiologicalandsocialfactors,inwhich psycho-logicalandphysiologicalstressduringpregnancy,including infectionsandinadequatenutrition,playarole.4High
lev-els of psychosocial stress are not only associated with a lowerbirthweight,but alsowithalowernumber of ante-natalconsultations.5
Interestingly, the study by da Rocha Neves et al.1
reportedthatnoneofthechildrenwerethin,whereas over-weight occurred in 4.4% of children. Nowadays, not only is impaired growth related to disadvantaged social con-ditions; overweight is also associated with low parental education,large householdsize,andlowersocioeconomic status.6Inaddition,increasingevidencesuggeststhatboth
impairedgrowthinearlylifeandchildhoodoverweightput the child at increased risk for cardiovascular disease in adulthood.7
Almost30% ofthechildren hadacognitiveimpairment or language impairment --- impairments defined as scores fallingonestandarddeviationbelowthemean.Incontrastto stuntedgrowth,cognitiveandlanguagedevelopmentwere not associated with biological risk factors, but only with socialones.Cognitivedevelopmentwasassociatedwiththe HOMEscore;languagedevelopmentwasassociatedwiththe HOMEscoreandthe qualityofthe neighborhoodin terms ofinfrastructure,andinteractionandtrust.The data sug-gestthatchildhoodcognitiveandlanguagedevelopmentin disadvantagedcommunitiesarestronglydependenton envi-ronmentalconditions,implyingthatimprovementofthese environmentalconditionsmaypromotechilddevelopment. Indeed,the reviewofKomro etal.8 indicatedthat
strate-gies that aim at the enhancement of social cohesion and improvement of the physical environment are associated withbettercognitivedevelopmentandchildhealth. How-ever,whetherspecificearlyinterventionprogramsthataim toteachparentshowtheybestcanstimulatetheir child’s development---programsthatareeffectiveininfantsat bio-logicalriskforcognitiveimpairment9---arealsoeffectivein
promotingcognitivedevelopmentinchildrenfromsocially disadvantagedfamiliesisnotclear.10
Does the absence of a contribution of biological fac-tors to impaired cognitive outcome imply that biological factorsdonotplayaroleindevelopmentaloutcomeof chil-dren in underprivileged societies? Presumably, that is not thecorrectconclusion. Inthe firstplace, daRochaNeves etal.assessedonlyafewprenatal,perinatal,andneonatal factors. For instance, no data were available on mater-nalprepregnancyweight,maternaldiseases,andmaternal smoking during pregnancy, as well as perinatal asphyxia. Thesefactorsareknowntohaveanadverseeffecton long-termdevelopmentaloutcome.11,12Forexample,termborn
infants prenatally exposed to maternal smoking on aver-agehavea10-pointreductionoftheirintelligencequotient (IQ)comparedtopeerswhohavenotbeexposedto mater-nalsmokingprenatally.13Secondly,developmentaloutcome
focused on cognitiveand language development,and the outcome of the psychomotor developmental index of the BSITD-III was not reported. It is conceivable that motor developmentat2---3yearsofagediddependonearly biolog-icalfactors,suchasbirthweightandgestationalage.Animal experiments14andearlyinterventionstudies9bothindicate
thatmotordevelopmentismorehardwiredinthebrainthan
cognitive development, implying that the former is more stronglydeterminedbybiologythanthelatter.Thirdly,da RochaNevesetal.assesseddevelopmentaloutcomeat2---3 years.Atthatage,onlyapartofcognitivefunctionshave been developed. With increasing age and with increasing complexityofthenervoussystem,newcognitivefunctions develop. Itis firstwiththeappearanceof afunction that theimpairmentof thatfunctioncan bediagnosed.This is the reasonthatmost cognitiveimpairments andcognitive and behavioral disorders first emerge at school age.15 It
is conceivable that with increasing age, the contribution ofearlybiologicalandsocialfactorsoncognitiveoutcome changes.Atearlyage---asdaRochaNevesetal.reported ---theinfluenceofsocialfactorsmaydominate.Butitmaybe surmised thatat schoolagetheimpactofearly biological factorsincreases,inlinewiththedevelopmentalorigin of healthanddiseasehypothesis.16,17Increasingevidence
sug-geststhatprenatalandperinataladversitiesmayhavealong lastingeffectondevelopmentandheath.16,18
The study by da Rocha Neves et al. draws the atten-tiontotheneedforimprovedantenatalandearlychildhood care in orderto facilitate child health and development. The first steptobetaken is toimproveprenatal care, in whichanadequatenumberofantenatalconsultationsplays apivotalrole.Notonlyisalownumberofantenatalvisits associatedwithstuntedgrowth---asthestudybydaRocha Nevesetal.demonstrated---itisalsoawell-knownrisk fac-torofneonatalmortalityandmorbidity.19TheWorldHealth
Organization (WHO) recommends at least four antenatal care visits, with the initial visitoccurring during the first trimester,thesecondbetween24and28weeksofgestation, andthethird andfourthat 32and36weeksofgestation, respectively.19 Factors that prevent women from
receiv-inganadequatenumberofpregnancyconsultationsinclude poverty,lackofinformation,thedistancetotheantenatal careservice,inadequateservices,andculturalpractices.20
This means that the biology of early lifeis largely deter-minedbysocio-economicconditions.Notonlyprenatalcare should betargeted toimprove child growth and develop-ment;postnatalrearingconditionsalsohaveastrongimpact onchilddevelopment.AsthestudybydaRochaNevesetal. demonstrated,thechild’scognitivedevelopmentislargely dependent on thehome environment, includingthe qual-ityofcaregiving,parentalresponsivity,andthepresenceof learningmaterial.
The outcome of the study by da Rocha Neves et al. stresses the need for long-term follow-up of infants who grow upineconomicallydisadvantaged situations.Only in this way will we understand how the complex interac-tion of biological and social adversities during early life impacts growth,health ---including cardiovasculardisease andobesity---anddevelopmentaloutcome,including cogni-tiveimpairmentsandpsychiatricmorbidity.Onlyinthisway willweknowwhichtypeofsocialandhealthservices dur-ingpregnancyandduringchildhoodareneededtoachieve optimalchildhealthanddevelopment.
Conflicts
of
interest
Socialandbiologicaldeterminantsofgrowthanddevelopment 219
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