Face, brow and shoulder presentations

Abstract

If the head presents and adopts an attitude of full extension, the result is a face presentation. The majority of these cases are not due to the causes as listed for malpresentation in general (Chapter 10) but are associated with an excessive tone of the extensor muscles of the fetus (muscles passing from the fetal spine to the head). Full extension may have taken place during labour which had commenced with the head of the fetus badly flexed in an occipito-posterior position or partially extended as a brow presentation. This is secondary face presentation which is more common than primary — that is, a fully extended cephalic presentation before the onset of labour. The incidence of face delivery is approximately 1 in 500.