Asymmetric heads and failure to climb stairs
Article Outline
There are two important papers in this issue of The Journal addressing motor skills, infants’ sleep position, and the implicit risk for sudden death. One, by Thompson, et al,1 shows that epidemiologic factors associated with death in the face-straight-down position (FSD) differ from factors present when infants die prone with face-to-side, or supine, or on their side. Thompson, et al, conclude that the physiologic mechanism(s) underlying FSD deaths may be different, and suggest, among other explanations, that head and neck tone and movements may predispose some infants to die FSD.
See related articles, p 623 and p 630
Majnemer and Barr2 also considered tone and motor skills affected by sleep position, and they have documented several related complications of supine sleeping among 155 infants from Quebec. They studied 4-month-old and 6-month-old infants and some infants from these groups at 15 months of age.
During a home visit, motor skills of the two different groups (4-month-olds, n = 83, and 6-month-olds, n = 72) were evaluated through the use of the Alberta Infant Motor Scale and the Peabody Developmental Motor Scale. Of the 4-month-olds, 16.4% usually slept prone; of the 6-month-olds, 30.6% usually slept prone. There were statistical if not clinical significant differences in motor skills among the 4-month-olds who usually slept prone versus those who usually slept supine. Among the 6-month-olds with presumably 2 more months of habitual prone or supine positioning, the differences were more significant. Eleven of 50 supine-sleeping infants who were 6 months old were “below the clinical cutoff for identification of gross motor delay,” and more than half were 1 standard deviation below the mean for gross motor scores. Prone-sleeping infants rolled over and sat independently more often at 6 months, and, in particular, failure to spend quality “tummy time” was associated with slower gross motor development among supine-sleeping infants.
By 15 months of age, prone infants were more likely to walk alone and to walk up stairs.
Importantly, characterization of the motor development differences were not based on parental recall but on scripted observations by physical therapists and occupational therapists who were unaware of the infants’ sleep position histories. Although their sample is small, important significant differences were detected between prone and supine-placed infants by blinded experts. Although limited information is provided concerning how subjects were recruited, their use of regression analyses to account for confounders is reassuring. Their paper joins several they cited that document developmental differences among infants positioned differently for sleep. This paper stands out because of the objective motor scales used.
At least three general points raised by this paper deserve further consideration.
First, the infants studied were at low risk for developmental delay, and, at 4 and 6 months in particular, were otherwise thought to be developing normally. Consequently, the authors caution against “needless referrals for investigation of developmental delay.” It seems likely that experienced pediatricians will comfortably heed their advice and consider the discrete delays in context, particularly for the 4- and 6-month-olds. However, 15-month-olds who do not walk alone may be a more significant concern to pediatricians looking for early signs of neuromyopathy. Furthermore, these findings should be extrapolated to other infants of similar age with much caution. Among other infants at higher risk for developmental delay (eg, former prematures), lasting motor delay may be accentuated by habitual sleep posture. Would the authors agree that referrals of recovering premature infants should still be triggered by conventional thresholds for clinical concern and that habitual sleep positioning not be considered?
Second, it would be interesting to know or estimate the sleep practices among the infants who formed the normal groups for the motor scales used. Presumably, the unknown but small percentage of those infants who slept supine did not experience any directed “tummy time.” Were the motor development norms likely to have been skewed in any important way by a potential confounder (prone sleep) that pertained to the majority and was not appreciated until recently?
Finally, concluding that there may be even a subtle downside to supine sleeping should cause nowhere near the furor that might have occurred 10 or 15 years ago, when recommendations for supine sleep were new. At that time, epidemics were predicted of babies battered because they would not sleep enough on their back and of fussy children with scarred esophagi whose gastroesophageal reflux was made much worse by supine positioning. For the most part, neither epidemic materialized. Ironically, too, the early idea of an epidemic of positional plagiocephaly, which apparently did come to pass, was initially rejected by staunch defenders of Back-to-Sleep from the United Kingdom.3, 4
Since supine sleep has become standard for infants, concern in moderation about motor delay seems to have been assuaged, without too much disagreement, by recommendations for supervised, awake “tummy time.” The findings of Majnemer and Barr suggest that both the substance and style of the response were correct.
References
- . Sudden infant death syndrome: risk factors for infants found face down differ from other side cases. J Pediatr. 2006;149:630–633
- . Association between sleep position and early motor development. J Pediatr. 2006;149:623–629
- . Observations on a recent increase in plagiocephaly without synostosis. Pediatrics. 1996;97:877–885
- . Positioning and sudden infant death syndrome: update. Pediatrics. 1996;98:1216–1218
PII: S0022-3476(06)00582-8
doi:10.1016/j.jpeds.2006.06.043
© 2006 Mosby, Inc. All rights reserved.
Refers to article:
- Association between sleep position and early motor Development
- Sudden infant death syndrome: Risk factors for infants found face down differ from other SIDS cases
