This study investigates the individual and contextual factors associated with small expressive vocabularies in Portuguese-speaking toddlers. Data were drawn from the validation study of the European Portuguese MacArthur-Bates Communicative Development Inventory: Words and Sentences, which included 1,042 children between the ages of 24 and 30 months. Boys were nearly three times more likely to have a small expressive vocabulary than girls. Later entry into childcare and lower maternal education were also significant predictors. In contrast, birth order had no significant effect. The probability of having a small expressive vocabulary increased with the number of co-occurring risk factors, thus, underscoring the multifactorial and ecological nature of early language development.
Cadime et al. (Wed,) studied this question.