Abstract
The recent advance of three-dimensional/four-dimensional ultrasound has clearly demonstrated details of fetal movement. Many musculoskeletal tissues and their innervation are associated with hand/finger positions and movements. This article focuses on details of fetal hand/finger positioning and movement in early pregnancy in vivo. From our data, mild adduction of the thumb and atonic fingers were observed from 11 weeks of gestation and the appearance of the palm was clearly different from that at 9 and 10 weeks. Fetuses start to clench and unclench their fists from 12 weeks and independent movement of each finger is occasionally seen from 13 or 14 weeks. In our series of fetuses with congenital central nervous system diseases, fetuses had normal hand/finger positioning and movements. We present two cases with congenital hand/finger malpositioning – one had an overlapping finger which was conspicuous after 13 weeks; the other had contractural malpositioning of the wrist demonstrated from 11 weeks. There may be different mechanisms associated with muscular and tendon variation between abnormal palmar/wrist flexion and abnormal digital flexion. Three- and four-dimensional ultrasound may reveal further details of fetal behaviors in utero.