Malpresentation - breech and transverse lie. Presentation refers to the way in which the baby is approaching the cervix. The usual way is head down, called a vertex presentation. Any other presentation is abnormal (and therefore described as mal- or bad). The most common malpresentation is breech, whereby the baby tries to leave the uterus bottom first. This may be because the pelvis is too small to accommodate the baby's head, but it may just be the way the baby lies. It is common up until about 30 weeks of pregnancy, when there's plenty of room for the baby to turn round, but after 36 weeks it is unusual. While it might be possible to persuade the baby to adopt the head down position, they are often stubborn. While breech delivery is feasible it is associated with an increased rate of complications, and many feel that the best mode of delivery is by Caesarean section (where the baby is delivered by opening the abdomen and the uterus at an operation). In transverse lie the baby lies across the abdomen, and vaginal delivery is unlikely.