|
|
|
Progress in Labour
Progress in labour depends on the 3 Ps that we have just talked about. Let's start by looking at the first two- the passage which is the woman's pelvis and the passenger - the baby.
The head of the baby is said to be engaged in the pelvis when the widest diameter of the presenting part (normally the head unless the baby is breech) passes the pelvic inlet. Here are some measurements of the pelvic inlet or brim and the fetal head.
|
Pelvic Brim |
Pelvic cavity |
Pelvic Outlet |
Activity: What do you think - is it all going to fit??
The transverse diameter of the pelvic brim is 13 cm and the largest diameter of the fetal head is 13 cms so it looks like a tight squeeze! But then if we look at the AP diameter of the pelvic cavity this is only 12 cm. The pelvic outlet though is back to 13 cm at the widest bit. How will this baby manage to get through this pelvis?
