Background: In previous research, an age-related developmental trend towards increasing arm flexion has been found for cephalic fetuses.
Aim: To determine if the development of arm posture in breech fetuses is comparable to that of cephalic ones.
Subjects and methods: Fetal arm posture was studied longitudinally by means of real-time ultrasound in 13 healthy breech and 10 healthy cephalic fetuses. Observations started from 33 weeks gestational age until birth and were performed weekly in the breech group and every 2 weeks in the cephalic group.
Results: No difference could be found in arm posture between the left and the right arm in either group. Both breech and cephalic fetuses showed a clear preference for flexion in elbow and finger joints at all studied ages. After 36 weeks gestational age, the breech group showed significantly less wrist flexion when compared to the cephalic group (p = 0.037). A clear preference for location of the fetal hands near the fetal head could be observed for both groups.
Conclusions: As there is no evidence for an abnormal neuromotor development in healthy breech fetuses, the observed difference in wrist flexion is probably due to differences in intrauterine environment. Because of the preference for location of the hands in the vicinity of the fetal head, breech fetuses probably experience a less restricted environment (in the upper part of the uterus) than cephalic fetuses (in the lower part of the uterus).