Developmental milestones are skills the majority of children achieve by a given age.  At age 18 months, a child should be able to walk well, finger-feed, imitate others, and follow a 1-step command without a gesture (eg, retrieve an object when asked).  An 18-month-old should also say ≥3 words in addition to "mama" and "dada."  This patient has appropriate motor and social skills but babbles and says only 1 word ("mama"); these findings are suggestive of an isolated language delay (Choice E).

Language is the most commonly delayed developmental milestone, and any child with language delay should have an audiology evaluation to assess for hearing loss as a potential contributing factor.  Infants and toddlers with developmental delays should also be referred for early intervention; although many children with isolated language delay will catch up in preschool, early initiation of speech therapy results in improved and more rapid acquisition of skills (Choice B).

(Choice C)  Selective mutism is a failure to speak in a specific social situation (eg, school) but not in others (eg, home).  It is often associated with anxiety, especially social phobia.  This child's language impairment is not specific to a certain situation.

(Choice D)  Autism spectrum disorder is characterized by impaired social communication/interactions and restricted, repetitive patterns of behavior or interests typically presenting by age 2.  Although language delay can be the first sign of autism, the diagnosis is unlikely in this child who has age-appropriate social interactions with her family (eg, showing father her drawing, imitating a phone call).

Educational objective:
Failure to say ≥3 words in addition to "mama" and "dada" at age 18 months is indicative of language delay.  Initial evaluation includes audiology testing to assess for potential hearing loss.