Examining Behavioral Interventions for Infancy and Early Toddlerhood: A Systematic Review of Intervention Effects, Parameters, and Participants.

The analysis reported effects descriptively across single-case, quasi-experimental, and randomized studies, so the evidence is hard to compare. Many studies used short-term or proximal outcomes, such as frequency of vocalizations, and follow-up was not always collected or did not always persist. Intervention duration and dose were often unclear or incompletely reported, so the review cannot identify how much intervention was needed. Demographic information was missing for most participants: infant race was reported for 23% of infants, ethnicity for 13%, and parent race was not reported for 90% of participants. The samples were largely white and Western, with 84% of studies having author affiliations in the United States, so generalizability to other communities is limited. Some randomized trials showed no effect on communication outcomes, so positive findings from single-case and quasi-experimental studies need cautious interpretation. Many interventions included caregiver training, coaching, and routine embedding together, so the effect of any single component cannot be separated. The review protocol was developed before searching but was not preregistered.

The funding section names the National Institute of Mental Health and Neurosciences and the University of Minnesota College of Education and Human Development. No author conflict-of-interest declarations are provided in the supplied text.

Do not conclude that these behavioral interventions are proven treatments for any infant communication or motor delay. The review reported effects descriptively across heterogeneous experimental, single-case, and quasi-experimental studies, many outcomes were proximal, dosage was often unclear, and some randomized trials showed no effect.