PHYSIOLOGICAL VARIATIONS IN THE PIGMENTATION OF NEWBORN-INFANTS

Skin pigmentation is a physiological feature of great value and useful ness from both an anthropological point of view and a clinical point o f view. This article is a first approach to the study of the skin pigm entation of 126 full-term newborn infants (37-42 weeks gestational age ) at the Maternity Hospital ''La Paz'' (Madrid, Spain) using the refle ctance method. We provide the normal patterns, which have to be taken into account when applying this method to detect transcutaneous biliru bin and some physiopathological conditions, such as hyperbilirubinemia , anemia, plethora, and hormonal disturbances. Measurements of the ref lectance were taken at the forehead, the internal and external aspects of the arm, the thorax, and the gluteus with blue, green, and amber t ristimulus filters. With all filters the least pigmented zone was the thorax, and the most pigmented zone was the forehead; the internal asp ect of the arm, the gluteus, and the external aspect of the arm were i ntermediate in increasing order. Our data confirm a higher pigmentatio n at birth than during the first year. We think that the idea of cepha locaudal progression of hyperbilirubinemia must be rejected. Our resul ts also indicate that the thickening of the skin with gestational age is one of the most important factors in the skin color changes of newb orn infants with an apparently different rhythm in males than in femal es.