Normal Labor and
Delivery
The Obstetrics and Gynecology
Hospital of Fudan University
Jing-Xin Ding

According to the New Shorter Oxford
English Dictionary (1993), toil, trouble,
suffering, bodily exertion, especially when
painful, and an outcome of work are all
characteristics of labor.
Definition

Labor is the period from the onset of
regular uterine contractions until expulsion
of the fetus and the placenta, and it is
defined as that occurring after 28
completed weeks of gestation.



Preterm delivery occurring after 28 weeks and
before 37 completed weeks of gestation. In
some developing countries, this time point has
been advanced to 20 gestational weeks.
Term delivery occurring after 37 weeks and
before 42 completed weeks of gestation.
Postterm delivery occurring after 42 completed
weeks of gestation.
CHAPTER 1 THE HYPOTHESIS OF
PARTURITION INITIATION
1. Mechanic theory
UTERINE QUIESCENCE During the
early stage of pregnancy, a
remarkably period of myometrial
quiescence is imposed.
CERVICAL SOFTENING By the end of
pregnancy, easily distensible, increase in
tissue compliance
Uterine awakening or activation
During the end stage of pregnancy, the fetus compressed
the lower segment and cervix of the uterus, and mechanic
effect induced the initiation of labor.
 There is no doubt that multifetal pregnancy and hydramnios
lead to an increased risk of preterm birth.
 It is likely that uterine distension acts to initiate expression
of
contraction-associated proteins (CAPs) in the myometrium.

2. Endocrine theory
The myometrial changes preparing it
for labor contractions probably
results from alterations in the
expression of key endocrine proteins
that control contractility. These
proteins include the oxytocin and its
receptor, prostaglandin and its
receptor, estrogen, progesterone,
and endothelin.
Prostagladin,PG


PG can promote the ripening of the cervix,
and start the contraction of the uterine.
It can be synthesized in uterine muscle,
placenta, etc.
Oxytocin and oxytocin receptor


Induce labor and promote the contraction
of the uterine muscle.
The uterine sensitivity to oxytocin is
increased before the initiation of labor.
Classical Progesterone
Withdrawal and Parturition



In species that exhibit progesterone withdrawal,
progression of parturition to labor can be
blocked by administering progesterone to the
mother.
In pregnant women, however, there are
conflicting reports as to whether or not
progesterone administration can delay the timely
onset of parturition or prevent preterm labor.
Further research may help explain its differential
action and how it could be better used to
prevent preterm labor.
Endothelin, ET


Induce the contraction of the uterus.
Induce the synthesis and release of PG.
Fetal Contributions to Initiation
of Parturition


The ability of the fetus to provide endocrine signals that
initiate parturition has been demonstrated in several
species.
This signal was shown to come from the fetal hypothalamicpituitary-adrenal axis .
3. Neuromediator theory


The uterine contraction is controlled by
the autonomic nerve.
It is still uncertain the role of autonomic
nerve in the initiation of labor.
Summary



Labor onset represents the culmination of
a series of biochemical changes in the
uterus and cervix.
These result from endocrine and paracrine
signals emanating from both mother and
fetus.
Not fully defined.
CHAPTER 2 THE FACTORS
DECIDING LABOR AND DELIVERY
Force of the labor
Birth canal
Fetus
Mental and psychological factors
I Force of the labor


Uterine Contractions — Main force
Maternal intra-abdominal pressure
and the contranction of levator
ani — Ancillary forces
Characteristics of the uterine
contractions
Rhythmicity
 Symmetry
 Polarity
 Retraction effect

1. Rhythmicity
Each contraction increase progressively in
intensity and maintains the maxium
intensity and then diminishes gradually.



the uterine baseline tone -- from 8 to 12
mm Hg
25 mm Hg at commencement of labor to
50 mm Hg at the end of first stage
During second-stage labor, aided by
maternal pushing, contractions of 100 to
150 mm Hg are typical.

At the beginning, the contracts occurs
every 5-6 minutes, and last 30 s. With the
progression of labor, frequency increases
to every 1-2 min and the duration
increases to 60 s when the cervix is fully
dilated.
2. Symmetry
The normal contractile
wave of labor
originates near the
uterine end of the
fallopian tubes.
Thus, these areas
act as "pacemakers".
Contractions spread from the pacemaker area
throughout the uterus at 2 cm/sec, depolarizing
the whole uterus within 15 seconds.
3. Polarity

Intensity is greatest in the fundus

Diminishes in the lower uterus.

Presumably, this descending gradient of
pressure serves to direct fetal descent toward
the cervix as well as to efface the cervix.
4. Retraction effect

The muscle fiber retracts after contractions, and
the cavity of the uterus becomes small, and the
fetus is forced to descend.
Maternal intra-abdominal
pressure -- pushing




Contraction of the abdominal muscles
simultaneously with forced respiratory efforts
with the glottis closed is referred to as pushing.
Similar to that with defecation, but the intensity
usually is much greater.
After the cervix is dilated fully, the most
important force in fetal expulsion is that
produced by maternal intra-abdominal pressure.
Accomplishes little in the first stage. It exhausts
the mother, and its associated increased
intrauterine pressures may be harmful to the
fetus.
The contraction of levator ani
The contraction of levator ani muscle
contributes to:
 the internal rotation, extention and
expulsion of the fetal head in the 2nd
stage of labor
 the delivery of placetenta in the 3rd stage
of labor.
II Birth canal


Bony Pelvis
The soft birthing canal
Bony Pelvis
Pelvic Planes
1.The pelvic inlet plane
2.The mid plane of pelvis--the plane of least
diameter
3.The pelvic outlet plane
The pelvic inlet plane

bordered by the pubic crest anteriorly, the
iliopectineal line of the innominate bones
laterally, and the promontory of the
sacrum posteriorly.
Four diameters: anteroposterior,
transverse, and two oblique diameters.

The obstetric conjugate of the inlet -distance between the promontory of the
sacrum and the symphysis pubis. Normally,
this measures 11 cm.


The transverse diameter is constructed at right
angles to the obstetrical conjugate and
represents the greatest distance between the
linea terminalis on either side.
Each of the two oblique diameters extends from
one of the sacroiliac synchondroses to the
iliopectineal eminence on the opposite side.
The mid plane of pelvis--the plane
of least diameter


the most important from a clinical standpoint,
because most instances of arrest of descent
occur at this level.
It is bordered by the
lower edge of the pubis
anteriorly, the ischial
spines and sacrospinous
ligaments laterally, and
the lower sacrum
posteriorly.

The interspinous diameter, 10 cm or
slightly greater, is usually the smallest
pelvic diameter. The anteroposterior
diameter through the level of the ischial
spines normally measures at least 11.5 cm.
The plane of the pelvic outlet



two approximately triangular areas with a common base
The apex of the posterior triangle is at the tip of the
sacrum, and the lateral boundaries are the sacrosciatic
ligaments and the ischial tuberosities.
The anterior
triangle is formed
by the area
under the pubic
arch.




The obstetric anteroposterior diameter
extends from the inferior margin of the pubis to
the sacrococcygeal joint.
The transverse (bituberous) diameter
extends between the inner surfaces of the ischial
tuberosities —an average of 9 cm
The posterior sagittal diameter extends from
the middle of the transverse diameter to the
sacrococcygeal joint —an average of 8.5 cm
The bituberous diameter
+ the posterior sagittal
diameter >15 cm, then
the fetus can be
delivered through the
posterior triangle.
Pelvic axis
-- an imaginary curved line that passes through
the centers of the various diameters of the
pelvis.
The pelvic axis first goes inferior and posterior, and
then inferior, and then inferior and anterior.
Inclination of
pelvis

The angle which the plane of the pelvic
inlet makes with the horizontal plane
when the patient is standing. The degree
is usually 60 °, if it is too much, the
engagement and delivery is difficult.
The soft birthing canal




the lower
uterine
segments
the cervix
the vagina
the pelvic floor
Formation of the Lower Uterine
Segments

The lower uterine segment is derived
from the isthmus which is about 1 cm
in nonpregnant uterus, and when the
labor is started, with regular
contractions of the upper uterine
segment, it distended to 7 to 10cm.
the Physiological Retraction Ring

As a result of the lower segment thinning
and concomitant upper segment
thickening, a boundary between the two is
marked by a ridge on the inner uterine
surface—the physiological retraction ring.
Cervical Changes


two fundamental changes—
effacement and dilatation
For an average-sized fetal head to
pass through the cervix, its canal
must dilate to a diameter of
approximately 10 cm.
Effacement of cervix


Cervical effacement is "obliteration" or
"taking up" of the cervix.
It is manifest clinically by shortening of
the cervical canal from a length of about
2-3 cm to a mere circular orifice with
almost paper-thin edges.
Dilatation of
cervix



The process of cervical effacement and dilatation
causes the formation of the forebag of amnionic
fluid, which is the leading portion of the amnionic
sac and fluid located in front of the presenting part.
As uterine contractions cause pressure on the
membranes, the hydrostatic action of the amnionic
sac in turn dilates the cervical canal.
In the absence of intact membranes, the pressure
of the presenting part against the cervix and lower
uterine segment is similarly effective.
A. Before labor, the
primigravid cervix is
long and undilated in
contrast to that of the
multipara, which has
dilatation of the internal
and external os.
B. As effacement begins,
the multiparous cervix
shows dilatation and
funneling of the internal
os. This is less apparent
in the primigravid cervix.
C. As complete effacement
is achieved in the
primigravid cervix,
dilation is minimal. The
reverse is true in the
multipara.
Pelvic Floor Changes during
Labor


The most marked change consists of the
stretching of levator ani muscle fibers. This is
accompanied by thinning of the central portion
of the perineum, which becomes transformed
from a wedge-shaped, 5-cm-thick mass of tissue
to a thin, almost transparent membranous
structure less than 1 cm thick.
The extraordinary number and size of the blood
vessels that supply the vagina and pelvic floor
result in substantive blood loss if these tissues
are torn.
III Fetus



Size of fetus
Fetal lie, presentation and position
Fetal abnormalities
FETAL HEAD
Important sutures and fontanelles

two frontal, two parietal, and two
temporal bones, along with the occipital
bone.
Sutures
The membrane-occupied
spaces between the
cranial bones are
known as sutures.




The sagittal suture lies between the parietal bones and
extends in an anteroposterior direction between the
fontanelles, dividing the head into right and left sides.
The lambdoid suture extends from the posterior
fontanelle laterally and serves to separate the occipital
from the parietal bones.
The coronal suture extends from the anterior
fontanelle laterally and serves to separate the parietal
and frontal bones.
The frontal suture lies between the frontal bones and
extends from the anterior fontanelle to the glabella (the
prominence between the eyebrows).
Fontanelles
The membrane-filled
spaces located at the
point where the
sutures intersect are
known as fontanelles.


The anterior fontanelle (bregma) is at the intersection of
the sagittal, frontal, and coronal sutures. It is diamond
shaped and measures approximately 2×3cm, and it is
much larger than the posterior fontanelle.
The posterior fontanelle is Y- or T-shaped and is found
at the junction of the sagittal and lambdoid sutures.

Clinically, they are useful in
diagnosing the fetal head position.
Diameters


Occipitofrontal Diameter
(11.3cm), extends from the
external occipital protuberance to
the glabella. The fetus usually
engage by this diameter.
Suboccipitobregmatic
Diameter (9.5cm), the
presenting anteroposterior
diameter when the head is well
flexed, and it is the shortest
anteroposterior diameter . It
extends from the undersurface
of the occipital bone at the
junction with the neck to the
center of the anterior
fontanelle.

Occipitomental
Diameter (13.3cm), the
presenting
anteroposterior diameter
in a brow presentation
and the longest
anteroposterior diameter
of the head; it extends
from the vertex to the
chin.


Biparietal Diameter (9.3cm), the largest transverse
diameter; it extends between the parietal bones.
This diameter detected by antenatal ultrasonic
examination was used to estimate the size of the fetus.
2. Fetal lie and presentation

Fetal Lie. The lie is the relation of the
long axis of the fetus to that of the mother,
and is either longitudinal or transverse.

Fetal Presentation. The presenting part
is that portion of the fetal body that is
either foremost within the birth canal or in
closest proximity to it.
3. Fetal abnormalities

When certain part of fetus is enlarged in
fetal abnormalities, for example, conjoined
twins, hydrocephalus, dystocia will occur.
IV Maternal mental and
psychological factors



Psychologic support to the women during
labor is very important.
The provision of continuous psychologic support
during labour by doulas, as well as nurses,
family or friends is associated with improved
maternal and fetal health and a variety of other
benefits.
A doula, also known as a labour coach, is a
nonmedical person who assists a woman before,
during or after childbirth, as well as her partner
and/or family by providing information, physical
assistance and emotional support.
CHAPTER 3 MECHANISM OF LABOR
WITH OCCIPUT PRESENTATION



The positional changes in the presenting
part required to navigate the pelvic canal
constitute the mechanisms of labor.
Left occiput anterior (LOA) position is the
most common fetal position
The cardinal movements of labor are
engagement, descent, flexion, internal
rotation, extension, external rotation, and
expulsion.
ENGAGEMENT



The mechanism by which the biparietal
diameter—the greatest transverse
diameter in an occiput presentation—
passes through the pelvic inlet is
designated engagement.
In nulliparous women, the fetal head
engage 1 or 2 weeks before labor.
In multiparous women, the fetal head
usually engage after the onset of labor.
A normal-sized
head usually does
not engage with
its sagittal suture
directed
anteroposteriorly.
Instead, the fetal
head usually
enters the pelvic
inlet either
transversely or
obliquely.
DESCENT



This movement is the first requisite for
birth of the newborn.
In nulliparas, engagement may take place
before the onset of labor, and further
descent may not follow until the onset of
the second stage.
In multiparous women, descent usually
begins with engagement.
Descent is brought about by one or more of
four forces:
(1) pressure of the amnionic fluid,
(2) direct pressure of the fundus upon the
breech with contractions,
(3) bearing down efforts of maternal
abdominal muscles
(4) extension and straightening of the fetal
body.
FLEXION

As soon as the descending head meets
resistance, whether from the cervix, walls
of the pelvis, or pelvic floor, flexion of the
head normally results.

In this movement, the chin is brought into
more intimate contact with the fetal thorax,
and the appreciably shorter
suboccipitobregmatic diameter is substituted
for the longer occipitofrontal diameter.
INTERNAL
ROTATION

This movement
consists of a turning
of the head in such a
manner that the
occiput gradually
moves toward the
symphysis pubis
anteriorly from its
original position.
EXTENSION


After internal rotation, the sharply flexed
head reaches the vulva and undergoes
extension.
When the head presses upon the pelvic
floor, however, two forces come into play.


The first, exerted by the uterus, acts more
posteriorly, and the second, supplied by
the resistant pelvic floor and the
symphysis, acts more anteriorly.
The resultant vector is in the direction of
the vulvar opening, thereby causing head
extension.

With progressive distention of the perineum and
vaginal opening, an increasingly larger portion of
the occiput gradually appears. The head is born
as the occiput, bregma, forehead, nose, mouth,
and finally the chin pass successively over the
anterior margin of the perineum.
EXTERNAL ROTATION

The delivered head next undergoes
restitution.

If the occiput was originally directed
toward the left, it rotates toward the left.
This movement apparently is brought
about by the same pelvic factors that
produced internal rotation of the head..

Restitution of the head to the oblique position is
followed by completion of external rotation to
the transverse position, a movement that
corresponds to rotation of the fetal body, serving
to bring its bisacromial diameter into relation
with the anteroposterior diameter of the pelvic
outlet. Thus, one shoulder is anterior behind the
symphysis and the other is posterior.
EXPULSION

Almost immediately after
external rotation, the
anterior shoulder appears
under the symphysis
pubis, and the perineum
soon becomes distended
by the posterior shoulder.
After delivery of the
shoulders, the rest of the
body quickly passes.



During labor, these movements are
sequential but also show great temporal
overlap.
For example, as part of the process of
engagement, there is both flexion and
descent of the head.
As a result, the fetus is transformed into a
cylinder, with the smallest possible cross
section passing through the birth canal.
CHAPTER 4 DIAGNOSIS OF
THREATENED LABOR AND LABOR
THREATENED LABOR
 Before actual labor begins, a number
of physiologic preparatory events
usually occur. And these are called
threatened labor.
The manifestation of threatened labor



Lightening
False Labor
Bloody show
Lightening


Lightening may be noted by the mother
as a flattening of the upper abdomen and
an increased prominence of the lower
abdomen.
Two or more weeks before labor, the
fetal head in most primigravid
women settles into the brim of the
pelvis. In multigravida, this often does
not occur until early in labor.
False Labor




During the last 4 to 8 weeks of pregnancy, the
uterus undergoes irregular contractions that
normally are painless.
Such contractions appear unpredictably and sporadically
and can be rhythmic and of mild intensity. In the last
month of pregnancy, these contractions may occur more
frequently, and with greater intensity.
These Braxton Hicks contractions are considered
false labor in that they are not associated with
progressive cervical dilatation or effacement.
They may serve, however, a physiologic role in
preparing the uterus and cervix for true labor.
Bloody show




Prior to the onset of parturition, the cervix is
frequently noted to soften as a result of increased
water content and collagen lysis.
Simultaneous effacement, or thinning of the
cervix, occurs as it is taken up into the lower
uterine segment.
Consequently, patients often present in early labor with a
cervix that is already partially effaced.
As a result of cervical effacement, the mucous plug
within the cervical canal may be released. The onset of
labor may thus be heralded by the passage of a small
amount of blood-tinged mucus from the vagina
(“bloody show”).
In Labor

It is defined as progressive cervical
effacement and dilatation resulting
from regular uterine contractions
that occur at least every 5 minutes
and last 30 to 60 seconds.
STAGES OF LABOR

Total stage of labor is from the onset of
regular uterine contractions to the delivery
of the baby and placenta.
3 stages of labor
The first stage is from the onset of true labor to
complete dilation of the cervix.
primiparous patients: 11-12h, multiparous patients
6-8h.
 The second stage is from complete dilation of
the cervix to the birth of the baby.
primiparous patients: 1-2h, less than 2 h.
multiparous patients much faster, less than 1h.
 The third stage is from the birth of the baby to
delivery of the placenta.
5-15min, less than 30 minutes.

CHAPTER 5
CLINICAL
MANIFESTATION AND MANAGEMENT OF
FIRST STAGE OF LABOR
CLINICAL MANIFESTATION OF THE
FIRST STAGE
1.



Regular uterine contraction.
From the onset of labor, it occur every 5-6
minutes and last about 30 seconds.
With the progression of labor, the uterine
contractions increase progressively in intensity.
At the same time, frequency increases to every
2-3 min, and the duration increases to 50-60
seconds.
When the cervix is nearly fully dilated, the
contractions last to 1min or even longer, and
rest for only 1-2 min.
2. Dilatation of cervix


Dilatation of the cervix is determined
by vaginal examination.
If progress is slow, evaluation for uterine
dysfunction, fetal malposition, or
cephalopelvic disproportion should be
undertaken.
3. Descent of fetal head


Determined by vaginal examination.
The level of the lowest presenting fetal
part in the birth canal is described in
relationship to the ischial spines.
4. Rupture of membranes

Rupture of membranes usually occurs
when the cervix is nearly fully dilated.
MANAGEMENT OF THE FIRST
STAGE OF LABOR


On admission the general condition of the
patient is assessed, her pulse rate and
blood pressure are recorded, and her
urine is tested for protein.
By abdominal examination the
presentation and position ot the fetus, and
the relation of the presenting part to the
brim of the pelvis, are determined.


Abdominal examination will also show the
frequency and strength of the uterine
contractions. The fetal heart rate is counted for
a full minute, and any abnormality of rate or
rhythm is noted.
A vaginal examination will show the degree of
dilatation of the cervix, whether the membrane
are intact or ruptured, and the level and position
of the presenting part.
Partogram

Once the labor has become established,
all events during labor are noted on a
partogram—a most useful graphical record
of the course of labor.

Routine observations of the mother’s pulse rate
and blood pressure, with an assessment of the
strength of the uterine contractions are entered
on it. Records of the findings at successive
vaginal examinations are plotted on a graph,
showing the dilatation of the cervix and the
descent of the fetal head in centimeters against
the time in hours.



The curve obtained is compared with an average normal
curve for primigravidae or multigravidae as may be
appropriate. If the patient’s progress is normal her curve
will correspond with the normal curve, or “lie to the left”
of it.
If for any reason labor is not progressing normally
dilatation of the cervix will become slower or may cease,
and the patient’s partogram will be “to the right” of the
normal curve.
Certain steps should be taken in the clinical management
of the patient during the first stage of labor.
Uterine Activity


Uterine contractions should be monitored every 30
minutes by palpation for their frequency, duration, and
intensity. With the palm of the hand resting lightly on the
uterus, the time of contraction onset is determined. Its
intensity is gauged from the degree of firmness the
uterus achieves.
For high-risk pregnancies, uterine contractions
should be monitored continuously along with the
fetal heart rate. This can be achieved electronically
using either an external tocodynamometer or an internal
pressure catheter in the amniotic cavity.
Fetal Monitoring


The fetal heart rate should be evaluated by
either auscultation with a DeLee stethoscope, by
external monitoring with Doppler equipment, or
by internal monitoring with a fetal scalp
electrode.
In patients with no significant obstetric risk
factors, the fetal heart rate should be
auscultated or the electronic monitor tracing
evaluated every 1-2h in the latent phase of labor,
and at least every 15-30 minutes in the active
phase of the first stage of labor and at least
every 15 minutes in the second stage of labor.
DILATION OF CERVIX AND
DESCENT OF FETAL HEAD
Measurement of progress
 During the first stage, the progress of
labor may be measured in terms of
cervical effacement, cervical dilatation,
and descent of the fetal head.
Phases

The first stage of labor consists of
two phases: a latent phase, during
which cervical effacement and early
dilatation(to 3cm) occur, and an
active phase, during which more
rapid cervical dilatation occurs, the
cervix dilate from 3cm to 10cm.
And the active phase has 3
component parts



acceleration phase the cervix dilates from
3-4cm, normally takes 1h and 30 min.
maximum acceleration phase the cervix
dilates from 4-9cm, normally takes 2h.
deceleration phase the cervix dilates
from 9-10cm, normally takes 30 min.
Length




The length of the first stage may vary in relation
to parity; primiparous patients generally
experience a longer first stage than do
multiparous patients.
Because the latent phase may overlap
considerably with the preparatory phase of labor,
its duration is highly variable.
It may also be influenced by other factors, such
as sedation and stress.
This phase normally takes 8h, and the
maximum is 16 h in primiparous patients.


The active phase begins when the cervix
is 3 cm dilated in the presence of regularly
occurring uterine contractions. The
minimal dilatation during the active phase
of the first stage is nearly the same for
primiparous and multiparous women: 1
and 1.2cm/hour, respectively.
This phase normally takes 4h, and
the maximum is 8 h.
Descent of fetal head



The level—or station—of the presenting fetal
part in the birth canal is described in relationship
to the ischial spines.
When the lowermost portion of the presenting
fetal part is at the level of the spines, it is
designated as being at zero (0) station.
As the presenting fetal part descends from the
inlet toward the ischial spines, when it is 3,2and
1 cm above the ischial spines, the designation is
–3, –2, –1. When it is 1, 2,3 and 4cm blow the
spines, as the presenting fetal part descends, it
is then +1, +2, +3, +4.

The descent of fetal head is not obvious in
the latent phase, and is accelerated in the
active phase, usually 0.86cm/h.
Rupture of membranes



Rupture of membranes usually occurs
when the cervix is nearly fully dilated.
Once the membrane is ruptured, the fetal
heart should be monitored, and the color
and amount of Amnionic Fluid should be
noted.
And the time of rupture should be
recorded.
Blood Pressure

During uterine contractions, the maternal
blood pressure usually elevated 5-10
mmHg. The blood pressure should be
monitored every 4-6 hours once the labor
is started.
Maternal Position.


If the head is engaged there is no need for the
patient to remain in bed during early labor. If
she is up and about, the weight of the liquor and
fetus helps to dilate the cervix, and pressure on
the lower segment stimulates the uterus to
contract.
If she is lying in bed, the lateral
recumbent position should be encouraged
to ensure perfusion of the uteroplacental unit.


There may be a frequent desire to pass water
during the first stage. If the bladder becomes
full and the patient cannot empty it a soft
catheter should be passed, as a full bladder has
an inhibiting effect on the uterine contractions.
Although it is common practice to give an enema
and to clip or shave the vulval hair, there is little
to show that either of these practices is
necessary, and many women dislike them.
Vaginal Examination

During the latent phase, particularly when the
membranes are ruptured, vaginal examinations
should be done sparingly to decrease the risk of
an intrauterine infection. In the active phase,
the cervix should be assessed
approximately every 2 hours to determine
the progress of labor. Cervical effacement
and dilatation, the station and position of the
presenting part, and the presence of molding or
caput in vertex presentations should be recorded.
Amniotomy


The artificial rupture of fetal membranes may
provide information on the volume of amniotic
fluid and the presence or absence of meconium.
In addition, rupture of the membranes may
cause an increase in uterine contractility.
Amniotomy incurs risks of
chorioamnionitis if labor is prolonged and
of umbilical cord compression or cord
prolapse if the presenting part is not
engaged.
CHAPTER 6 CLINICAL MANIFESTATION
AND MANAGEMENT OF SECOND STAGE
OF LABOR

This stage begins when cervical dilatation
is complete and ends with fetal delivery.
CLINICAL MANIFESTATION

With full cervical dilatation, which signifies the
onset of the second stage, a woman typically
begins to bear down. With descent of the
presenting part, she develops the urge to
defecate. Uterine contractions and the
accompanying expulsive forces may now last
1minute or longer and recur at an interval no
longer than 1 minute. The abdominal pressure,
together with the uterine contractile force,
combines to expel the fetus. During the second
stage of labor, fetal descent must be monitored
carefully to evaluate the progress of labor.

With each contraction, the
perineum bulges increasingly.
The vulvovaginal opening is
dilated by the fetal head, and
the fetal head is seen at the
vulva at the height of each
contraction. Between the
contractions the elastic tone of
the perineal muscles push the
head back , and this is called
head visible on vulval gapping.

The perineal body and vulval outlet
become more and ore stretched, and the
encirclement of the largest head diameter
by the vulvar ring is known as crowning of
head.


Six movements of the baby enable it to
adapt to the maternal pelvis: descent,
flexion, internal rotation, extension,
external rotation, and expulsion.
The second stage generally takes
from 1 to 2 hours in primigravid
women and from 5 to 60 minutes in
multigravid women.
MANAGEMENT OF THE SECOND
STAGE
Fetal Monitoring
 During the second stage, the fetal heart
rate should be monitored continuously or
evaluated every 5-10 minutes. Fetal heart
rate decelerations (head compression or
cord compression) with recovery following
the uterine contraction may occur
normally during this stage.
Bearing Down

With each contraction, the mother should
be encouraged to hold her breath and
bear down with expulsive efforts.
Vaginal Examination

Progress should be recorded
approximately every 30 minutes during
the second stage. Particular attention
should be paid to the descent and flexion
of the presenting part, the extent of
internal rotation. During the second stage
of labor, the retracted cervix is no longer
palpable.
Delivery of the Fetus

When delivery is imminent, the patient is
usually placed in the lithotomy position,
and the skin over the lower abdomen,
vulva, anus, and upper thighs is cleansed
with an antiseptic solution.
The modified Ritgen maneuver

The midwife must control the head to
prevent it being born suddenly, and it must
be kept flexed until the largest diameter
has passed the vulval outlet. A toweldraped, gloved hand may be used to exert
forward pressure on the chin of the fetus
through the perineum just in front of the
coccyx. Concurrently, the other hand exerts
pressure superiorly against the occiput. The
downward pressure increases flexion of the
head and allows a controlled delivery. This
maneuver is simpler than that originally
described by Ritgen (1855), and it is
customarily designated the modified Ritgen
maneuver.

Once the head is
delivered, the
airway is cleared of
blood and amniotic
fluid using a bulb
suction device. The
oral cavity is cleared
initially and then the
nares are cleared. A
second towel is used
to wipe secretions
from the face and
head.

After the airway has been cleared, an
index finger is used to check whether the
umbilical cord encircles the neck. If so, the
cord can usually be slipped over the
infant’s head. If the cord is too tight, it
can be cut between two clamps.
CHAPTER 7 CLINICAL
MANIFESTATION AND
MANAGEMENT OF THIRD
STAGE OF LABOR
clinical manifestation: placental
separation
Management
the care of the newborn
assist the delivery of placenta
to exam the placenta and fetal
membranes
to check the soft birth canal
to prevent PPH
to observe the general state of health
manual removal of placenta