Now as part of normal labor, let's just discuss
the stages of labor.
Stage 1.
This is the onset of labor until 10 centimeters dilated.
During stage 1 contractions cause the cervix to change
and it causes the fetus to descent into the pelvis.
Phase 1 can be divided into two phases, the latent phase
which is the onset of contractions until 4 centimeters,
and the active phase.
This is from 4 centimeters to 10 centimeters dilated.
Now when we speak of cervical change, we're talking about
cervical dilation, effacement and station.
Dilation refers to how open the external os of the cervix is.
This is measured in centimeters and we do this
with a digital exam.
And you can see here from the example,
as we go from 1 centimeters to 2 centimeters to 3 centimeters,
the external os is opening more.
When we talk about effacement we talk about how thick
the cervix is.
So when a woman that's not pregnant her cervix feels kind
like the tip of your nose.
It's pretty thick.
As labor progresses, the cervix starts to thin out
and it starts to shorten.
Now in a primigravida woman, the cervix will thin out
more than it dilates.
The multiparous is the opposite.
The cervix will usually open a little bit
and then starts to thin out.
And then you see here at 10 centimeters the cervix is fully
fully thinned out.
We call that a 100% effaced.
Now when we say station, that means we're referring
to the presenting part and relationship
to ischial spines of the mom.
You can see at the ischial spines we call that 0 station.
1 centimeter above is -1 station.
2 centimeters above is -2.
On the flip side, 1 centimeter down is +1 station.
2 centimeters down is +2 station.
Now we have some parameters that we consider to be
normal for the first stage of labor.
For primiparous woman in latent labor, we expect that to last
6 to 11 hours.
For a multiparous we expected it to last 4 to 8 hours.
Now for that active phase of labor for the primiparous woman,
we expect her cervix attain 1.2 centimeters per hour.
And then for the multiparous 1.5 centimeters per hour
is the norm.
Now moving on to stage 2.
Stage 2 of labor is from 10 centimeters dilated until
the delivery of the infant.
During stage 2, the fetus is entering the pelvis through
the cardinal movements of labor which begin in Stage 1
and completed in Stage 2.
So let's go to cardinal movements of labor.
First we have engagement.
This is when the head is starting to come
into the pelvis.
Then we have descent as the head goes down through the pelvis.
Then we have flexion.
And basically, that's when the chin is tucked into the chest.
Internal rotation as the head starts to turn.
Then we have extension as the head comes underneath
the pubic symphysis.
External rotation, the head is going to return to the same plain
that it was in prior to internal rotation.
And then we have expulsion which is delivery of the fetus.
Now if you are having a little trouble remembering these steps,
I have a little-- let's say metaphor to help you remember.
We can think it like a wedding.
First you get engaged.
Then you descend down the aisle.
Then you flex your head to pray.
Then you internally rotate as you turn to your new spouse.
Then you extend as you lift your head up to further kiss.
Then you have external rotation as you turn back towards
the congregation.
And then expulsion as you walk down the aisle.
I hope that little tip, it helps you remember these movements.
Now for Stage 2, let's consider our norm.
So for primiparous with an epidural 3 hours.
A multiparous with an epidural 2 hours.
Primiparous without an epidural 2 hours.
And a multiparous without an epidural 1 hour.
So these are our norms that we expect for how long it takes
for mom pushing in Stage 2 of labor.
Now Stage 3 of labor.
This is from the delivery of the infant until delivery
of the placenta.
To deliver the placenta,
we have gentle downward tractional umbilical cord,
while the other hand puts gentle traction on the uterus.
In the normal setting we expect the placenta to deliver
within 30 minutes.