Early Literacy Research Library (ELRL) - Article

Reading Aloud and Child Development: A Cluster-Randomized Trial in Brazil

Weisleder, A., Mazzuchelli, D.S.R., Lopez, A.S., Neto, W.D., Cates, C.B., Gonçalves, H.A., Fonseza, R.P., Oliveira, J., Mendelsohn, A.L. (2018) Reading Aloud and Child Development: A Cluster-Randomized Trial in Brazil. Pediatrics, 141(1), e20170723.,

Access: FREE/Open Access

Publication year


study description

Cluster-randomized study

core topic(s)

Early Literacy , Early Relational Health , Shared Reading

Population Characteristics

Infant/Newborn , International , Poverty/Low-Income , Urban

Exposures, Outcomes, Other

Child Development (general) , Disparity/Adversity , Home Visitation , Language and Literacy Development , Parent-Child Relationships/Interactions , Programs and Interventions (other) , Social-Emotional , Technology and Digital/Screen-Based Media , Universidade do Bebê


We sought to determine if a parenting program focused on the promotion of reading aloud enhanced parent-child interactions and child development among low-income families in northern Brazil.


Universidade do Bebê (UBB).

outcomes evaluated

Parent-child interactions and child development.


This study was conducted in Boa Vista, a medium-sized city in northern Brazil (population 284 313) with a high poverty rate.26 The intervention was delivered in free educational child care centers (Casas-Mãe) serving low-income children ages 2 to 4 years.


This was a cluster-randomized study of educational child care centers randomly assigned to receive an additional parenting program (intervention) or standard child care without a parenting component (control). Parent-child dyads were enrolled at the beginning of the school year and were assessed at enrollment and at the end of the school year. Families in intervention centers could borrow children's books on a weekly basis and could participate in monthly parent workshops focused on reading aloud. We compared parents and children in intervention and control centers 9 months after the start of the intervention on measures of parent-child interaction and child language, cognitive, and social-emotional development.

sample size

n=566 (dyads, total at enrollment); n=279 (dyads, enrollment intervention); n=287 (dyads, enrollment control); n=464 (dyads, total at follow-up)


Measures of Parenting Outcomes:

    • Cognitive Stimulation in the Home: StimQ
    • Interactive Reading: parent-child interactions while sharing a children’s book, coded by using the Adult/Child Interactive Reading Inventory (ACIRI)
    • Physical Punishment: Physical Punishment subscale of the Socolar Discipline Survey

Measures of Child Outcomes:

    • Child Receptive Vocabulary: Teste de Vocabulário por Imagens Peabody (TVIP), a Brazilian adaptation of the Peabody Picture Vocabulary Test.
    • Child Expressive Vocabulary: Teste Infantil de Nomeação, a Brazilian adaptation of the Boston Naming Test.
    • Child IQ: 2 subscales from the Brazilian version of the Snijders-Oomen nonverbal intelligence test (SON-R).
    • Child Working Memory: Teste Infantil de Memória de Trabalho (TIMT).
    • Child Phonological Short-Term Memory: word/nonword repetition task.
    • Child Socioemotional Competence: Competence Domain of the Infant-Toddler Social and Emotional Assessment-Revised (ITSEA).
    • Child Behavior Problems: externalizing problems subscale from the Portuguese version of the Child Behavior Checklist (CBCL)–Parent Report.

Measure of Sociodemographic and Depressive Covariates: child variables, family characteristics, and parental depressive symptoms assessed using a Brazilian.


Five hundred and sixty-six parent-child dyads (279 intervention; 287 control) in 12 child care clusters (26-76 children per cluster) were assessed at enrollment; 464 (86%) contributed follow-up data. Parents in the intervention group engaged in significantly greater cognitive stimulation (Cohen's d = 0.43) and higher quantity and quality of reading interactions (d = 0.52-0.57) than controls; children in the intervention scored significantly higher than controls on receptive vocabulary (d = 0.33), working memory (d = 0.46), and IQ (d = 0.33).


An innovative program focused on the promotion of parent-child reading aloud resulted in benefits to parent-child interactions and to child language and cognitive development that were greater than those provided by educational child care alone. This promising approach merits further evaluation at scale.


First, there was potential for bias because randomization groups were not equivalent on all measures at baseline and because children assessed at follow-up had higher baseline scores than those lost to follow-up. Importantly, intervention impacts were found after adjusting for baseline differences. Nevertheless, the authors of future studies should consider the inclusion of larger numbers of clusters, which would likely reduce sampling error and enhance group equivalence. Second, selection bias may have occurred as a result of excluding children whose parents were not available at enrollment; this, and the location of the study in a single city, may limit generalizability. Third, although we used measures with evidence of validity in Brazil, a lack of standardization of some of the instruments may limit the interpretation of our findings. In addition, the use of survey instruments for some parent outcomes, together with their administration in the intervention location, could have introduced bias. Finally, the intervention was delivered by facilitators with university degrees for assessing program efficacy; further work will be needed to determine the implications for scaling.