NEW YORK (Reuters Health) - The incidence of infantile hemangiomas has grown in recent years, with low birth weight the leading risk factor driving the increase, new study findings indicate.

Although most infantile hemangiomas are benign and resolve on their own, Dr. Beth A. Drolet and colleagues point out in the Journal of Pediatrics for November that "a significant percentage cause medical morbidities or permanent scarring."

To elucidate features influencing the development of infantile hemangioma, Dr. Drolet, at the Medical College of Wisconsin in Milwaukee, and other members of the Hemangioma Investigator Group conducted a case control study, which included 420 children with infantile hemangioma and 353 control subjects.

Their study confirmed several recognized risk factors, including female sex, Caucasian race, and preterm birth. However, they report, "low birth weight rather than prematurity per se is the most significant risk factor for developing infantile hemangioma."

For every 500-gram decrease in birth weight, the likelihood of the birthmark rose by 40%.

Patients with infantile hemangioma were twice as likely as control subjects to have an affected first-degree relative (33% vs 15%, p < 0.001), and the authors suggest that genetic background could lower the threshold for infantile hemangioma.

Dr. Drolet's team calls for research to establish evidence-based approaches to management of infantile hemangioma, as well as the need to teach providers how to distinguish benign cases from those with high potential for complications and need for treatment.

J Pediatr 2008;153:712-715.