Observations on a recent increase in plagiocephaly without synostosis.

OBJECTIVE To verify and determine the cause of an increase in the referral of infants with plagiocephaly without synostosis (PWS) to a single tertiary craniofacial center. DESIGN A chart review was performed for 269 infants with a diagnosis of PWS who presented to a single tertiary craniofacial center between 1979 and 1994. The pattern of referral for PWS was analyzed using both simple linear regression and time series regression analyses. In addition, the referral pattern for PWS was compared with that for infants seen at the same center who received a diagnosis of synostotic plagiocephaly. Changes in the distribution of several demographic, perinatal, and clinical variables during the study period were also assessed. Finally, in an effort to identify correlates of the risk of PWS developing, characteristics of patients who were Missouri residents and presented between 1992 and 1994 were evaluated and compared with those of the 1993 Missouri live birth cohort. SETTING The Cleft Palate and Craniofacial Deformities Institute, St Louis Children's Hospital, Washington University Medical Center. RESULTS The average annual number of referrals to our center for PWS in the period 1992 to 1994 was more than sixfold greater than that for the preceding 13 years. There was a statistically significant increase in the annual number of referrals to our center during the 16-year study period. Moreover, there was evidence that the average annual increase in referrals was significantly greater during the last 3 years (1992 through 1994) of the study than in the first 13 years. This shift in the referral patterns is roughly contemporaneous with the American Academy of Pediatrics recommendations regarding infant sleep position. There was no evidence that either the mean number of referrals or the average annual increase in referrals for patients with synostosis changed during the study period. Among patients with PWS, the average age at presentation did not change during the study period. There were also no significant changes in the distribution of other demographic, perinatal, and clinical variables. When compared with the Missouri birth cohort, infants with PWS were significantly more likely to be boys and to have been delivered by forceps. There was also some evidence that patients with PWS were more likely to be born prematurely and to be products of multiple-gestation pregnancies. These associations were, however, of only borderline statistical significance. CONCLUSION Referrals to our center for PWS increased markedly in 1992 relative to previous years. The temporal coincidence of this increase with the American Academy of Pediatrics recommendation to avoid the prone sleeping position, to reduce the risk of sudden infant death syndrome, suggests a possible causal relationship. If this association is causal, education regarding the need for head position rotation coupled with that for sudden infant death syndrome should obviate positional PWS.