Summary
Highlights
Fetal presentation refers to the part of the fetus that enters the pelvic inlet first. The most preferred presentation is head first (vertex). Other presentations include breech (buttocks or feet first), scapula (shoulder first), and mentum (chin first).
The first letter of the fetal position code indicates whether the presenting part is on the left (L) or right (R) side of the maternal pelvis.
The second letter identifies the presenting part: occiput (head), sacrum (buttocks/feet), mentum (chin), or scapula (shoulder).
The third letter indicates the orientation of the fetal back relative to the mother's pelvis: anterior (A) for back towards the mother's belly, posterior (P) for back towards the mother's spine, or transverse (T) for sideways.
Fetal station measures the degree of descent of the fetus into the maternal pelvis, relative to the maternal ischial spines. If the presenting part is above the ischial spines, the station is negative. When it reaches the ischial spines, it's zero. As it descends further into the birth canal, the station becomes more positive.