"...The pediatrician should continue to encourage
supervised "tummy time" on firm surfaces when the infant is awake
and being observed."
Source: Persing J, James H, Swanson J, Kattwinkel J.
Prevention and management of positional skull deformities in
infants. American Academy of Pediatrics Committee on
Practice and Ambulatory Medicine, Section on Plastic Surgery
and Section on Neurological Surgery. Pediatrics 2003 Jul;112(1
Pt 1):199-202.