Facial Expressions in Small for Gestational Age Newborns.

What a newborn’s response to sweetness can reveal

A newborn’s facial response to a sweet solution is one way to study the earliest reactions to food. This correspondence examines how those responses should be compared when infants have grown poorly before birth.

The authors respond to a study that reported few taste-response differences between newborns who were small for their gestational age and control infants. They propose a different interpretation of the published pattern: the response to sweetness should be considered relative to each group’s response to water, rather than treating the water response as an isolated finding. Water can provide a baseline for facial movements that are not specific to sweetness.

The comparison changes the question. If control infants respond more strongly to sucrose than to water, while small infants respond similarly to both, the difference may concern the added pleasurable response to sweetness. The letter connects this interpretation with the authors’ earlier trial in preterm newborns, in which poorer fetal growth was associated with fewer positive responses to a sweet solution.

The proposed link to later food preference remains a hypothesis: reduced early responsiveness to sweetness might contribute to seeking more highly palatable food later. The letter does not follow newborns into childhood or demonstrate that sequence. Its contribution is methodological and conceptual, showing how the choice of baseline and the use of birth weight as a continuous measure can influence the interpretation of early sensory behavior.