There have been reports of various effects of the "back to sleep campaign" for infants, such as an increased number of infants with flattened occiput,1 something we used to attribute to parental inattention.
During the past several months, some of our colleagues and we have noted several infants who seem quite normal except that their gross motor milestones, as assessed by the Denver II screening test,2 are occurring out of the usual sequence. We have seen 5- to 6-month-old infants who, when prone, do not push up with their arms to support their chest and head, and who cannot roll over from belly to back. At the same time, these infants can easily accomplish the presumably more difficult maneuver of rolling over from back to belly.
Schindler AM, Hausman C. Do We Need to Reassess Normal Gross Motor Milestones?. Arch Pediatr Adolesc Med. 2001;155(1):96. doi:10.1001/archpedi.155.1.95