Fetal position and skull shape.

The skull shapes of 615 consecutively born babies weighing over 2500 g were examined visually and by palpation. A characteristic deformity of the occiput was found which was strongly associated with breech presentation; it is suggested that this be termed hyptiocephaly. Severe forms of hyptiocephaly might partially explain the high incidence of occipital osteodiastasis in breech babies. A lesser occipital deformity was associated with occipito-posterior presentation. It was found that facial asymmetry declined with increasing parity. Statistical trends suggest that all of these abnormalities of skull shape are the effect, rather than the cause, of the abnormal fetal position.