NEW YORK (Reuters Health) - A number of factors, including gender and favorite head position -- but not sleeping position -- influence the severity of flat head syndrome in infants, researchers found in a study of 434 babies with the condition known medically as deformational plagiocephaly.

It is particularly noteworthy, the researchers say, that the severity of flattening was not associated with infant sleep position.

"We found a trend toward less flattening in infants who slept prone (face down), or in positions that were alternated," Dr. Albert K. Oh, of Brown University, Providence, Rhode Island, noted in a prepared statement.

"Interestingly," however, while sleeping supine (face up, on the back) has been a well established risk factor for the development of flat head deformity, "we were not able to demonstrate a logical correlation to indicate more severe flattening from the supine position," Oh said.

The researchers also found that males with flat head syndrome outnumbered females 2 to 1 and that infants with flat head were apt to be born early, at around 36 weeks, on average, instead of the normal 40 weeks.

Fewer than half of the infants suffered from tight neck muscles or neck muscle imbalance, a condition known as torticollis, but 80 percent were found to have "head tilt" -- abnormal position of the head.

It's also noteworthy, the researchers say, that there was no association between the use of orthotic devices and the severity of head flattening, which calls into question the effectiveness of the use of these devices in the treatment of or prevention of flat head syndrome, they say.

The researchers also found a link between multiple-birth pregnancies and the degree of head flattening. In the study, infants with flat head syndrome who were the product of a multiple-birth pregnancy were disproportionately higher than in the general population and greater than in previous studies. This was the only pregnancy-related variable the researchers found to be associated with the severity of flat head syndrome.

This study is significant, noted Oh, in that it identifies direct correlations between a variety of factors and the severity of flat head syndrome in infants. "Ultimately we have shown that there are certain clear risk factors for more severe flattening in infants," the researcher added.

SOURCE: The Journal of Craniofacial Surgery, March 2009.

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