Certified Pediatric Nurse (CPN)

Which of the following assessments would be the most concerning in a 3-month-old?

1. Closed posterior fontanel

2. Inability to roll over

3. Failure to track objects through visual fields

4. Failure to laugh

The correct answer is: Failure to track objects through visual fields

The concern regarding the failure to track objects through visual fields in a 3-month-old is significant because it may indicate a delay in visual development or neurological function. At this age, infants typically begin to visually track objects and show interest in their environment; this helps in developing their sensory perception and cognitive skills. If a 3-month-old is not tracking objects, it may warrant further evaluation to rule out issues such as visual impairment or developmental delays. In contrast, the closure of the posterior fontanel is a normal part of anatomical development and typically closes by 2 to 3 months of age. The inability to roll over might be a concern, but many infants do not typically start rolling over until around 4 to 6 months; thus, it would not usually raise significant alarm at this early stage. Failure to laugh may be concerning, as smiling often begins around 6 weeks to 3 months; however, the absence of laughter is not as strongly indicative of developmental issues compared to the inability to track visual stimuli. Thus, the inability to track objects is the most concerning assessment for a 3-month-old and warrants closer scrutiny.