Development of human palmar and digital flexion creases

To determine the timing of the development of the various palmar and digital creases, we examined the hands of 100 human fetuses obtained after therapeutic abortion. The fetuses ranged in age from 7 to 19 fetal weeks, with age being established by menstrual period dates and ultrasound examination before termination. Our observations show that palmar and digital creases develop between 8 and 13 fetal weeks. Digital creases are well defined by 10 weeks; palmar creases are consistently seen by 13 weeks of gestation. The volar pads are present from 8 to 14 fetal weeks. A hand malformation or specific insult that occurs before the time of crease development and that alters the form or function of the fetal hand can cause secondary alterations increase patterns of the hand.