Occiput Anterior Delivery
Step by step
The occiput anterior presentation is the most efficient way for a normally proportioned fetus to pass through a gynecoid pelvis and occurs in around 85% of all vaginal deliveries.
In an occiput anterior presentation
- the lie is longitudinal
- with a cephalic presentation
- the attitude is flexed
- the determining point is the occiput
- the eccentric pole is the occiput
- the point of rotation around the pubic symphysis is the posterior hairline.
The diameters of the head descending through the pelvis are the suboccipitofrontal diameter (10 cm) and the biparietal diameter (9.5 cm).
For a more detailed elaboration on the definitions used in labor refer to the course ‘Mechanisms of Labor’.