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.