It has been known that the development of skin creases on the sole of the foot occurs in late intrauterine life and that after birth this is a helpful clinical sign to determine gestational age. Until 36 weeks of gestation there are only one or two transverse skin creases on the anterior part of the sole. The posterior two-thirds of the sole are smooth. By 37 to 38 weeks of gestation more creases have appeared and in the full-term infant there is a complex series of criss-crossed creases covering the entire sole.
Since no racial differences in the presence or absence of this sign have ever been published a study was designed to compare the development of skin creases on the sole of the foot between Caucasian and Negro newborn infants.