Objective: To compare motor performance in infants sleeping in prone versus supine positions.
Study design: Healthy 4-month-olds (supine: n = 71, prone: n = 12) and 6-month olds (supine: n = 50, prone: n = 22) were evaluated with the Alberta Infant Motor Scale (AIMS) and Peabody Developmental Motor Scale (PDMS), and parents completed a positioning diary. Infants were reassessed at 15 months.
Results: At 4 months, motor scores were lower in the supine group and were less likely to achieve prone extension (P < .05). At 6 months, there were wide discrepancies on the AIMS (supine: 44.5 +/- 21.6, prone: 60.0 +/- 18.8, P = .005) and the gross motor PDMS (supine: 85.7 +/- 7.6, prone: 90.2 +/- 9.5, P = .03). Motor delays were documented in 22% of babies sleeping supine. Prone sleep-positioned infants were more likely to sit and roll. Daily exposure to awake prone positioning was predictive of motor performance in infants sleeping supine. At 15 months, sleep position continued to predict motor performance.
Conclusions: Infants sleeping supine may exhibit early motor lags, associated with less time in prone while awake. This has implications for accurate interpretation of assessment of infants at risk and prevention of inappropriate referrals. Rate of infant motor development appears influenced by extrinsic factors such as positioning practices.