Document Type



The skin color of 99 healthy White and 38 healthy Black infants between 25 and 44 weeks gestational age was measured by abridged reflectance spectrophotometry. No statistically significant sex differences were found, although White females are slightly ligher skinned, at all ages from at least 35 weeks gestational age, than White males. Black and White infants exhibit similar reflectance values until 32 weeks gestational age after which Whites become lighter skinned whereas Blacks become darker skinned. The changes in skin reflectance are due to changes in melanin production and distribution, hemoglobin, and perhaps carotene and bilirubin concentration, relative to changes in skin thickness and turbidity. Cross-sectional data on newborns during the first days of life demonstrate that these changes occur in utero. Longitudinal data, however, on infants within the same age range, demonstrate that they occur independently of the intrauterine environment. The foreheads of both Black and W hite term infants measured within hours after birth and never exposed to ultraviolet radiation, average 10-12% darker, respectively, than the medial aspect of the upper arm, indicating that the difference between exposed and non-exposed areas of the body, in children and adults, cannot be used a priori as a measure of “tanning capacity.”