A motor milestone change noted with a change in sleep position.

OBJECTIVE: To evaluate whether sleeping in the supine position resulted in changes in gross or fine motor developmental milestones observed at routinely scheduled well-child checkups at 4 or 6 months of age.
DESIGN: A retrospective chart review.
SETTING: One private pediatric practice involving 2 full-time and 2 part-time board-eligible or board-certified pediatricians.
SUBJECTS: The study included 343 full-term infants whose weights were appropriate or large for gestational age, had no history of hospitalization other than for normal newborn care, and were examined in the office for their 4-month well-child checkup within 2 weeks of being 4 months old.
METHODS: The Denver Developmental Screening Test-Revised was administrated at the 4- and 6-month well-child checkups. The primary sleep positions of the infants were determined by telephone survey, office interview, or letter after the 6-month checkup was completed. Background data collected from the mother for each mother-infant pair included maternal age at the time of birth, parity, and marital status, Medicaid status and ethnicity of the infant, and whether the infant was breast-fed.
RESULTS: Infants who slept in the side or supine position were less likely to roll over at the 4-month checkup than infants who slept primarily in the prone position (P < .001). No significant differences were found when comparison by maternal age, parity, or marital status, Medicaid status or ethnicity of the infant, or the use of breast-feeding were considered. Other motor milestones screened did not show statistically significant changes.
CONCLUSIONS: Sleep position significantly influences the age of achieving the gross motor developmental milestone of rolling over; infants who sleep in the side or supine position roll over later than infants who sleep in the prone position.