The parent brings a child to the clinic for a 12-month well visit. The child weighed 6 pounds 2 ounces and was 21 inches long at birth. Which finding will cause the nurse to intervene?

A) Height of 30 inches
B) Weight of 16 pounds
C) Is not yet potty-trained
D) Is not yet walking up stairs

Size increases rapidly during the first year of life. Birth weight doubles in approximately 5 months and triples by 12 months. This infant should weigh at least 18 (6 * 3) pounds by this calculation. This child needs the nurse to intervene for further assessment. Height increases an average of 1 inch during each of the first 6 months and about 1/2 inch each month until 12 months: 21 + 6 + 3 = 30 (30 inches is the predicted height). Patterns of body function are just now starting to stabilize. It is quite normal for a 12-month-old child to not be potty-trained or walking up stairs yet. These milestones usually occur in the toddler period of development (12 to 36 months).