Contributors to abnormal labour

When any of the 3 Ps are unfavourable, labour is likely to be ab­normal, resulting in the need for intervention, and an increased risk of morbidity or mortality. Malpresentation, malposition, and CPD are important contributors to abnormal labour and are associated with the following factors:

• Powers:

^■ Inefficient uterine activity

^■ Inefficient pushing

• Passages:

^■ Uterine abnormality—septum, bicornuate uterus, and fibroids

^■ Pelvic abnormality—android/anthropoid/platypelloid shape, fractures, and rickets

^■ Pelvic floor relaxation—epidural analgesia

^■ Placenta praevia

• Passenger:

^■ Prematurity

^■ Small-for-gestational age/growth-restricted fetus

^■ Large-for-gestational age/macrosomic fetus

^■ Fetal congenital abnormality

^■ Multifetal pregnancy

^■ Polyhydramnios.