Positional preference: prevalence in infants and follow-up after two years.

OBJECTIVES: 1) To determine the prevalence of positional preference in the general population of infants up to the age of 6 months; 2) to gather information on possible risk factors; 3) to determine the percentage of children with positional preference undergoing diagnostic evaluation and/or treatment; and 4) to assess the overall outcome of positional preference in infants and toddlers, with currently used diagnostic and treatment practices.
SETTING: Infant health care centers in The Netherlands.
METHODS: Seven thousand six hundred nine infants below the age of 6 months were screened for positional preference (cases: n = 623). Anamnestic data and physical signs of asymmetry of the range of motion and the shape of the head were recorded. These data were also registered of an immediate next child visiting the infant health care center with the same sex and about the same age but without positional preference (controls: n = 554). In a first follow-up study, 6 to 8 months after the original study, 468 of the 623 children with positional preference were reexamined for asymmetry of the range of motion and the shape of the head. In a second follow-up study, 24 to 32 months after the original study, 129 of 259 children who still had shown signs of asymmetry in the first follow-up study were again reexamined.
RESULTS: The prevalence of positional preference was 8.2% and was highest in children below 16 weeks of age. The boy:girl ratio was 3:2. Firstborns, premature children, and children with breech position at the time of delivery proved to have a higher risk for positional preference. The supine sleeping position of the child and a strong preference in offering the feeding always from the right or the left side were positively correlated with positional preference. In the first follow-up study, 12% still showed restricted active range of motion, 8% restricted passive range of motion, 47% asymmetric flattening of the occiput, and 23% of the forehead. Thirty-two percent of the children with positional preference had been referred for diagnostical/therapeutical intervention. In the second follow-up study, active range of motion was restricted in 6%, passive rotation in 2%, 45% had an asymmetric flattening of the occiput, and 21% of the forehead.
CONCLUSION: Positional preference is frequently observed (8.2%) in The Netherlands. It leads to referral, additional diagnostics and, if necessary, treatment of almost 1 of every 3 affected children. Extrapolated to the original population in 1995, 2.4% of all children would still have a restricted range of motion and/or flattening of the skull at the age of 2 to 3 years. The high prevalence of positional preference in infancy, the persistency of accompanying signs, the large number of children referred for further diagnostic and/or treatment, and the resulting high medical expenses strongly call for a primary preventive approach.positional preference, deformational plagiocephaly, asymmetry, infants, population-based study.