- [Voiceover] I thought the movies taught me
everything I needed to know about labor and delivery.
The water breaks, mom yells,
everyone rushes in to the hospital,
and after a few breathing exercise
and two or three really hard and loud pushes,
the baby arrives.
Well, reality couldn't be further from that.
For one thing, most of the time,
labor is preceded by a few signs
that tell the mom that the baby is about to come.
One of those signs is lightening.
One of those signs that tells the mom
that the baby is about to make his or her debut
is lightening or people like to call the drop.
And what it refers to is the baby's head engaging with
and sort of settling into mom's pelvis
which the mom can feel.
It feels like the baby is sitting lower in the abdomen
and this is my sort of diagram depicting that.
So I don't know if you can tell
but this is the pelvis and this here,
this here is the baby.
And you can see that the baby's head
is sort of nestled into and settled into mom's pelvis.
And that's called lightening.
Another one of those signs that tells mom
that baby is about to come is Braxton Hicks contractions.
They're called Braxton Hicks contractions
sometimes called practice contractions,
and that's exactly what they are.
They're uterine contractions
that occur as early as the first trimester.
But unlike real labor contractions,
they're infrequent, they're irregular
and they don't occur with a pattern.
As delivery approaches, Braxton Hicks contractions
tend to become more frequent
and they tend to become more uncomfortable.
And then another big sign of impending labor
is loss of the mucus plug
which the mucus plug is the mucus that seals
the opening to the cervix.
So it seals the endocervical canal.
The canal that's inside the cervix.
And when the cervix loosens up
and it dilates during labor,
the plug falls out.
And sometimes when that mucus plugs is blood-tinged
it's referred to as the bloody show.
It's referred to as the bloody show.
I always wondered what that was, the bloody show.
Okay, so those are some of the signs of impending labor
but what on earth is labor?
Well, labor is when you have regular uterine contractions
that lead to changes in the cervix,
in the passage of the baby.
So the contractions have to be regular.
They have to be patterned
and they have to lead to some change in the cervix,
and that's what labor is.
And we split labor up into three distinct stages
with each stage kind of having its own goal.
There's the first stage of labor.
So there's the first stage of labor,
the second stage of labor,
second stage of labor,
and the third stage of labor.
And we're gonna go through
each of these stages independently
starting with the first stage of labor,
which is the longest stage of labor.
The first stage of labor is all about
the cervix becoming fully dilated.
And what that means, what it means
for the cervix to become fully dilated
is that the cervix goes from being thick
and completely shut to thinning out
and opening up 10 centimeters.
10 centimeters is what we call completely dilated.
And that's a lot of change, right?
It doesn't happen all at once
instead it happens in three distinct phases.
The first stage of labor has three phases to it.
And the first of those phases is called the latent phase.
The latent phase, right?
During the latent phase,
contractions become stronger,
they become more frequent and more regular.
And most of what's happening during this phase
is the thinning or the effacement of the cervix.
That looks something like this.
You can see the cervix is becoming thinner, right?
Not too much dilatation is occurring.
In fact at most, the cervix will become
three centimeters dilated max during this phase.
This phase, the latent phase is actually
the most variable phase from woman to woman.
For a woman who's had kids before
we expect it to last anywhere from 10 to 12 hours
but for a woman who's having her very first baby,
it can take as long as 20 hours.
So that's a lot of variability.
Okay, so we hope that by the end of the latent phase
the cervix is maximally thinned out
so that during the next phase
which is called the active phase,
the active phase,
we can focus on the dilatation of the cervix, right?
During the active phase,
the cervix goes from being two to three centimeters dilated
to becoming eight to nine centimeters dilated.
It sort of looks like this, right?
You can see that the cervix is becoming dilated
or the space is increasing.
And this phase is what you can call
the most predictable phase of labor.
It's so predictable that we measure it to rate.
By that I mean that in a first time mom,
the cervix has to dilate at least
1.2 centimeters per hour
and that's in a first time mom.
And for a mom who's had multiple kids in the past,
the cervix has to dilate quicker
so at least 1.5 centimeters an hour.
It's that predictable,
that predictable that we have this rate for it.
So much so that if the cervix isn't dilating
at the rate that we expect it to,
we get really concerned.
That leaves us with the last phase
which is called the deceleration.
The deceleration phase
which some people like to call the transition.
Transition, so the deceleration phase and transition
are two interchangeable terms for this phase.
During this phase, the cervix continues to dilate
but more slowly than it did in the active phase.
In some women, this isn't as much a separate phase
as it is kind of an extension of the active phase.
So it kind of blends in with the previous phase.
Also the baby passes lower into the pelvis
and deeper into the birth canal during this phase.
Okay, so now we have a fully effaced, right,
so fully thinned out and a fully dilated cervix.
The second stage of labor marks the period
between when you have a fully dilated cervix
to the delivery of the baby.
For a lot of people,
this is what's known as the pushing stage.
And usually, usually, this should take less than an hour
in a woman who's done it before
and less than two hours in a first time mom.
But keep in mind that the use of something like an epidural
can prolong this stage so it slows things down.
Okay and then finally the final stage is stage three
which is the period between the delivery of the baby
and the delivery of the placenta,
and this shouldn't take any longer than 30 minutes.
So I hope that this has taken out some of the mystery
out of what normally occurs during labor.
But what about when things don't occur normally?
What about when labor isn't progressing as quickly
or as effectively as it should?
Well if that's the case then we need
to evaluate the three P's.
If labor isn't progressing the way that it should
we evaluate the three P's.
The first P is powers, right?
The first P is powers.
The second P is passenger.
Passenger.
Have powers, passengers.
And the last P is passage.
So the three P's, powers, passenger and passages
is what we sort of evaluate
if labor isn't going the way that it should,
if it's abnormal.
Powers, the first P refers to uterine contractions
or more specifically to the force that's generated
by the uterine muscles when they contract.
If there is an abnormality during labor,
we have to ask ourselves,
is it because the uterine contractions
aren't occurring frequently enough?
Are they not lasting long enough?
Or maybe are they not strong enough?
And we can assess that simply through observation.
Typically we think that during active labor,
we should have about three to five contractions
every 10 minutes, right?
We should have three to five contractions
every 10 minutes.
With each contraction lasting somewhere
between 40 and 60 seconds,
and each contraction being strong enough
that the uterus feels firm when you palpate it,
when you touch it.
Or if you prefer to use more objective measure
there are these devices called
intrauterine pressure catheters
that you can actually insert through the vagina
and onto the uterus
that will give you a numerical measure.
So a more objective measure
of how strong each contraction is.
Either way, we know that contractions during labor
have to be adequately frequent
and adequately strong to achieve labor.
And if they are not, we can use a drug such as oxytocin.
There is this drug called oxytocin
which causes the uterus to contract
to sort of help us along.
And you also have to think about
the second contributor to powers
and that's the bearing down efforts of the mom,
and you have to think about if those are strong enough.
If the mom is sort of pushing effectively
and strongly enough.
Okay, so if powers isn't the problem
then we need to consider the second P, passenger
which the passenger is of course the fetus.
Some things to consider about the fetus
include what its orientation is.
Whether the head, the feet
or the shoulders are delivering first, right?
Because that can affect thing.
We have to consider whether the head is flexed
or whether it's extended,
and of course how big the fetus' head is
is also important to think about
if you're having any abnormality in labor.
And then finally there's a last P or passage
which refers to mom's sort of bony pelvis
and the soft tissues of the birth canal.
So the cervix and the pelvic floor muscles, right?
Abnormal labor could be the result of something we call
cephalo, something we call cephalopelvic,
cephalopelvic disproportion.
Abnormal labor can be the result
of cephalopelvic disproportion.
Cephalo means head.
Pelvic refers to pelvis, right?
So we're talking about a disproportion
between the baby's head and the mom's pelvis.
Basically, the baby's head can't fit through mom's pelvis
either because baby's too big
or mom's pelvis is too small.
In either case, since you really
can't change either variable,
C-section tends to be the only
sort of treatment for this problem.
All right, so that's a brief, very brief overview of labor.
Hopefully the next time you see a Hollywood delivery
you'll appreciate exactly how much they're leaving out.