Photo (c) Amanda Rohde
Spending less time prone or on their stomach, since the release of the Back to Sleep recommendations to reduce the risk of SIDS, has caused some infants to roll over a little later than they used to though.
It can also cause some delays in picking up other milestones, including sitting up and crawling. Fortunately, by the time they were toddlers, these delays all seem to disappear no matter how your baby sleeps, so it likely more appropriate to describe these kids as having a 'lag' in their development and not a true delay. If you want to avoid this 'lag,' you might try some tummy time during the day.
Still, most infants roll over when they are between two to six months old, first from their front to their back, and then from their back to their front.
Sources:
Functional developmental evaluation. Prerequisite to habilitation. Capute AJ - Pediatr Clin North Am - 01-FEB-1973; 20(1): 3-26
Linguistic and auditory milestones during the first two years of life: a language inventory for the practitioner. Capute AJ - Clin Pediatr (Phila) - 01-NOV-1978; 17(11): 847-53
Clinical linguistic and auditory milestone scale: prediction of cognition in infancy. Capute AJ - Dev Med Child Neurol - 01-DEC-1986; 28(6): 762-71
The Denver Developmental Assessment (Denver II)
Association between sleep position and early motor development. Majnemer A - J Pediatr - 01-NOV-2006; 149(5): 623-629
