11.2.3 Is the baby head down or bottom down?
By the last month before birth, most babies are lying with their head towards the cervix of the uterus (Figure 11.3a). The head down position is called a cephalic presentation, and if the part of the fetal skull called the vertex comes down the birth canal first, it is the easiest presentation for childbirth. Doctors and midwives refer to the part of the baby that is pointing into the cervix of the uterus as the presenting part. In Figure 11.3a, the presenting part is the baby’s head, and in Figure 11.3b, the presenting part is the baby’s bottom. You will learn about other presentations (face, brow, shoulder) in the Module on Labour and Delivery Care.
Which part of the fetal skull is the vertex? (Think back to Study Session 6. You may wish to look again at Figure 6.5, which shows the bones of the fetal skull.)
The vertex is the area of the fetal skull midway between the anterior fontanel (the space between the bones at the front of the baby’s head), and the posterior fontanel (the space between the bones at the back of the baby’s head).