“A Pacifier-Activated Music Player . . .” has 2 fatal errors in methodology, rendering the findings meaningless, and is based on the questionable assumption that the quantity ingested reflects an infant’s feeding maturity.
First, the concealment (masking) of group assignment is badly flawed; unmasked nurses and parents could have influenced study outcomes of feeding intake and advancement. Infants receiving the plainly visible and audible bedside intervention (ie, multiple, pacifier-controlled exposures to recordings of mother’s voice) and control infants (ie, ad libitum use of a typical pacifier) were enrolled simultaneously. All nurses and parents had unlimited mutual contact and fed study infants. They were unmasked by free access to the intervention in progress. Additionally, intervention parents had full training and voice recording but control parents had only partial training. Obvious safeguards (eg, a sham control intervention and sham control parent training and pacifier-voice recording) were not used. The investigators themselves admit that an unknown number of nurses saw infants receiving the intervention. Yet there are no data about infant feeding by unmasked nurses and parents. Any NICU nurse can attest to the ease of “making” a preterm infant suck and ingest formula. An unmasked nurse could “push” an intervention infant toward the hoped-for study results (the ethics and quality of care of this practice, aside).
Second, signal (mother’s voice recording) and ambient (ongoing NICU sound/noise) sound levels were neither measured nor reported.1 The levels of pacifier-voice recordings during training may have been undetectably low or exceeded the infant’s threshold of physiologic or behavioral self-regulation. Either condition would eliminate training effects.
An infant’s ability to detect a signal in noise changes inversely with age: the younger the infant, the higher the signal level necessary for reliable detection against ambient background.
6-month-olds do not detect a signal in noise until it [the signal] is about 15 dB more intense than that needed by adults to make the same discrimination. . . . Children do not reach adult thresholds for detecting a signal in noise until age 10. . . Noisy environments may interfere with newborns’ and infants’ abilities to discriminate important signals such as mother’s voice and music. . . . In hospitals . . . the singular example of the mother’s voice, although intelligible to adults, may be indistinct or lost to her infant.2 (p. S70)
The AAP Recommended Standards for NICU include sound-level limits.3 Without sound-level data, conformity with AAP Standards and effective signal-to-noise ratios during pacifier-voice training are unknown. An unplanned effect of high pacifier-voice levels could be infants perceiving their mothers’ voice as aversive.4
Lastly, the study is based on the unexamined premise that the quantity ingested and not the quality of feeding behavior is the valid measure of feeding maturity. Are fast advancement goals as beneficial for infants as for third-party payers? Evidence suggests that feeding for quantity produces atypical neurobehavioral feeding development and the perception of feeding as aversive, both of which contribute to the large percentage of preterm infants with feeding problems.5
- Copyright © 2014 by the American Academy of Pediatrics