A 1-month-old boy is brought to your clinic after being born with asymmetric intrauterine growth...

This infant was born late preterm (36 weeks) with asymmetric intrauterine growth restriction (IUGR) and remains at the 3rd percentile. Although he is breastfeeding well, infants with IUGR and late prematurity often require enhanced caloric intake to support catch-up growth. MCCQE objectives emphasize optimizing postnatal nutrition in growth-restricted infants to promote appropriate weight gain while monitoring growth velocity.

Caloric fortification of expressed breast milk (or use of higher-calorie formula if needed) increases energy density without increasing feeding volume, supporting growth in infants who are small for gestational age. Simply continuing standard feeds may not provide sufficient calories for catch-up growth.

High-dose vitamin D is not indicated; routine supplementation (400 IU daily) is appropriate for breastfed infants. Early introduction of solids is not recommended before about 6 months of age. Switching to hydrolyzed formula is unnecessary without evidence of milk protein allergy.

Therefore, caloric-fortified feeding is the most appropriate next step to promote optimal growth in this infant.