In infancy, prior to cranial suture and fontanel calcification, the cr
aniofacial skeleton can be easily deformed by an externally exerted fo
rce, In this study, the relationship between the sleep position and sk
ull morphology was investigated, A group of 81 cleft lip and/or palate
infants without other systemic anomalies was first seen in the cranio
facial center at approximately 1 month of age, The sleep position of e
ach infant was recorded as supine, prone, or mixed type, The body and
skull growth were longitudinally measured at 1, 3, and 6 months of age
, Infants sleeping in the supine sleep position tended to have a wider
head width, shorter head length, and a larger cephalic index by 6 mon
ths of age, The opposite phenomena were observed in the prone sleep gr
oup, The mixed sleep group tended to have head width, head length, and
cephalic index between those of the supine sleep group and the prone
sleep group, During the first 3 months of life, the sleep position cou
ld mold the skull primarily in the dimension of head width, In conclus
ion, the supine sleep position may promote brachycephaly and the prone
sleep position dolichocephaly.