This study investigated how gross motor and fine motor development are influenced by sleep position.

From December, 2003 to September, 2005, for a year and 9 months, 800 children aged from 3 months to 16 months, who visited the Presbyterian Medical Center, Chonju, Korea were surveyed for motor development scale, sleep position and body weight

The sleep position came in order : 79.3 percent of supine position, 10.0 percent prone position and 10.7 percent side position. Gross motor scale and fine motor scale were not connected with sex. The prone position indicated remarkable increase on gross motor scale from 5-6 months, but stayed the same after 7 months. Fine motor scale was not related to age and sleep position. Gross motor scale and fine motor scale were higher on group weighing more than under average weight group.

This study showed that prone position did not influence gross motor scale after 7 months, affecting children of 5-6 months only. Hence, It is not recommended to use the prone position for a baby's fast gross motor development.