Most common cause of occipito-posterior presentation:

Occipito Posterior is a veex presentation with foetal back directed posteriorly. 10% at onset of labour. Occipito posterior may have association with anthropoid, most commonly, and android pelvis: The anthropoid pelvis is marked by an oval inlet (but the anteroposterior diameter exceeds the transverse), the pelvic side walls diverge, and the sacrum is inclined posteriorly. Its associated with Persistent occipito posterior presentation and Face to pubis delivery The android (male-like) pelvis, where the inlet is wedge shaped, the pelvic sidewalls are convergent, the ischial spines are prominent, the subpubic arch is narrow, and the sacrum is inclined anteriorly in its lower one third. It is likely to be associated with deep transverse arrest dystocia.