A birthmark survey in 500 newborns: clinical observation in two northern Taiwan medical center nurseries.

BACKGROUND The prevalence of birthmarks in Taiwanese newborns has not been well studied. How gender and maturity of newborns affect presentation and prevalence of vascular birthmarks, in particular, has not been well documented. The aim of this survey was to catalog the above-mentioned problems. METHODS From May 9 through July 14, 2000, 500 newborns in Linkou and Taipei Chang Gung Memorial Hospital nurseries were examined for the presence of birthmarks. The data were collected and stored in Excel software and analyzed using chi2-test and Fisher's exact test for statistical association. RESULTS The most common pigmentary birthmark was the Mongolian spot (61.6%), followed by congenital melanocytic nevi (0.6%), café-au-lait spots (0.4%), and nevi depigmentosus (0.4%). Vascular birthmark frequency was: salmon patch (27.8%), Port-Wine stain (0.6%), and hemangioma (0.2%). Other miscellaneous changes included preauricular sinus (0.6%), skin tag (0.6%), and accessory auricle (0.2%). Prevalence of the vascular salmon patch birthmarks in female infants and male infants was 31.0% and 26.6%, respectively, but the difference was not statistically significant (p = 0.51). The prevalence of vascular salmon patch birthmarks in full-term infants was 28.0%, and 25.8% in preterm infants. However, there was also no statistical difference (p = 0.96) between the two. The two nevus depigmentosus cases were isolated types and neither of these were distributed along the Blaschko lines. CONCLUSIONS The Mongolian spot was the most common birthmark in Taiwanese newborns, followed by the salmon patch. All of the other birthmarks had prevalence of less than 1%. The prevalence of vascular salmon patch birthmarks was noted in 31.0% of female infants and in 26.6% of male infants. The prevalence of vascular salmon patch birthmarks in full-term infants was 28.0% versus 25.8% in preterm infants. However, the findings regarding vascular birthmarks were not statistically significant between the differing gender and maturity groups.