Identification of biological and environmental risk factors for language delay: The Let's Talk STEPS study

• Delayed language can be defined at two years age.
• Environmental factors are powerful indicators for language development.
• Mother's concern is a valuable indicator for language delay.

The aim of this population-based study was to identify demographic factors for language delays at an early age. The risk analysis covered 11 biological and 8 environmental factors. The mothers’ concerns regarding language development were also examined. A total of 226 children from a Finnish cohort study were invited to participate in language assessments at 36 months. The test results for word finding and language comprehension were compared with parental questionnaires about children's vocabulary at 13 and 24 months.Regression analysis revealed that the father's social class (t = −2.79, p = 0.006) and working full time (t = −2.86, p = 0.005) significantly predicted children's language delay. In addition, language comprehension was significantly predicted by the mother's social class (t = −2.06, p = 0.041) and by gender, with an advantage to girls (t = −2.71, p = 0.008). Vocabulary at 24 months was a powerful predictor for lexical development (t = 4.58, p < 0.0001) and language comprehension (t = 4.85, p < 0.0001) at 36 months. Mothers’ concerns were correlated with children's limited lexicons as early as 24 months (r = 0.31, p < 0.0001) and poor language comprehension (r = −0.35, p < 0.0001) at 36 months. Mothers were especially concerned if the parents needed special education during school years.At the population-level, gender was the most powerful biological factor in predicting language delays. Similarly, both parents’ social status had predictive value for the child's language development. In addition, it was found that the mother's concern about her child's slow language acquisition should be taken into account when making decisions regarding special support.