labor

Normal labor and delivery
• Definition of labor
• Causes of onset of labor
• Phisiology of labor
• Mechanism of labor
• Changes before labor (premonitory symptoms)
monitoring of labor
• Management
• Episiotomy & care

Definition (1)
Labor is the process by which the viable products of
conception (fetus, placenta, cord and membrane ) are expelled
from the uterus. (whole process, series of events ,viable fetus)
It is defined as the progress effacement and dilation of the
cervix, resulting from rhythmic contraction of the uterine
musculature.
preterm labor—prior to 37 completed weeks

Definition (2)
DELIVERY : it is the expulsion or extraction
of a viable fetus out of the womb.
it is not synonymous with labor,delivery can take place without
labor as in elective C.S. Delivery may be vaginal either
spontaneous or aided or it may be abdominal.
Naegeles formula : EDD can be calculated 9m
+ or – 1 week.

Definition (3)
• Normal labor (eutocia) :
labor is called normal if it fulfils the following criteria.
1) spontaneous in onset and at term.
2) with vertex presentation.
3) without undue prolongation.
4) natural termination with minimal aids.
5) without having any complications affecting the health
of the mother and /or the baby.

Definition (4)
• Abnormal labor (dystocia): any deviation from
the definition of normal labor.
• Normal labor :eutocia:the series of events that
takes place in the genital organs in an effort to
expell the viable products of conception out of
the womb through the vagina in to the outer
world

Causes of onset of labor (1)
• uterine distension: over-stretching of the uterus may play
some part in onset of labor. Stretching effect on the
myometrium by the growing size of the fetus and amniotic
liquor can explain the onset of labor at least in twins or
hydramnios. This uterine stretch increases Gap junction
protiens,receptors for oxytocin & contraction protiens.
• Feto-placental contribution: fetal hypothalamus- pituitary
adrenal axis .prior to onset of labor , increased release of
CRH -ACTH - stimulates fetal adrenals - increased cortisol
secretion - accelerated production of estrogen and
prostaglandins from the placenta.

• The probable modes of action of oestrogen are:
--increase the release of oxytocin from maternal pituitary
--promotes the synthesis of receptors for oxytocin in the
myometrium and decidua.
--accelerates lysosomal disintegration inside the decidual cells
resulting in increased prostaglandin synthesis.
--stimulates the synthesis of myometrial contractile protein
---increase the excitability of the myometrial cell membranes.

• Progesterone: increased fetal production of
dehydroepiandrosterone sulphate and cortisol may
inhibit the conversion of fetal pregnenolone to
progesterone, altering the estrogen : progesterone
ratio. The alteration in the estrogen:progesterone
ratio rather than the fall in the absolute
concentration of progesterone which is linked with
prostaglandin synthesis.

• prostaglandins:it is important factor to initate & maintain
labor.amnion , chorion , decidual cells & myometrium.
Synthesis is trigged by ---rise in estrogen level, altered
estrogen-progesterone balance, mechanical stretching in late
pregnancy, increase in oxytocin receptors specially in the
decidua vera, infection, separation or rupture of the
membranes.
• Oxytocin:it is probable that myometrial contraction is more
dependent on its own readiness to respond to oxytocin.
oxytocin level reaches the maximum at the moment of the birth.

• Nervous factors: labor may also be initiated
through nerve pathways.alpha & beta
adrenergic receptors present in myometrium.

Premonitory symptoms (1)
The premonitory stages may begin 2-3 weeks before the
onset of true labor in primigravidae and a few days before
in multiparae. The symptoms are inconsistent and may
consist of the following:
false labor (false pain)
lightening
blood show
cervical changes

• False labor
It usually appears prior to the onset of true labor
pain, by one or two weeks in primigravidae and by a few
days in multiparae.
The woman feels pain and discomfort in the abdomen
and these are mistaken for labor pain.

These Braxton-Hicks contractions cause the
patient’s discomfort, it occur throughout pregnancy,
late in pregnancy they become stronger and more
frequent.
But these contractions are not associated with
progressive dilation of the cervix, and therefore do not
fit the definition of labor.
It is irregular and ineffective. It is not only a
distressing feature to the woman but also annoying to
the relatives.

• False pain has the following features:
1.discomfort is characterized as over the lower
abdomen and groin areas
2.without effect on dilation of the cervix (not
associated with progressive dilation )
3.typically shorter in duration
4.less intense
5.relieved by administration of a sedative or
ambulation

• Lightening
Few weeks prior to the onset of labor specially in
primigravdae, the presenting part sinks into the pelvis.
The patient reports the sensation that the baby has gotten
less heavy, the result of the fetal head descending into the
pelvis.
The patient often notice that the lower abdomen is
more prominent and the upper abdomen is flatter, and there
may be more frequent urination as the bladder is compressed
by the fetal head.

This descending diminishes the fundal height and
hence minimises the pressure on the diaphragm.
This makes the woman more comfortable and has an
easier time breathing.
It is a welcome sign, as it rules out cephalopelvic
disproportion and other conditions preventing the head
from entering the pelvic inlet.

• Blood show
With the onset of labor, there is profuse cervical secretion.
Simultaneously, there is slight oozing of blood from rupture
of capillary vessels of the cervix and from the raw decidual
surface caused by separation of the membranes due to
stretching of the lower uterine segment. Expulsion of cervical
mucus plug, mixed with blood is called show.
This bloody show results as the cervix begins thinning
out with the concomitant extrusion of mucus from the
endocervical glands.
Patients often report the passage of blood-tinged mucus
late in pregnancy.

Cervical changes:
several days prior to the onset of labor the cervix
becomes ripe.
A ripe cervix is soft, less than 1.3cm in length,
admits a finger easily and is dilatable. Cervical
effacement is common before the onset of true labor.

Ture labor or in labor
• Painful uterine contractions
• Increasingly intense and frequent
• Is associated with progressive cervical
effacement and dilation
• Regular contraction occur every 5 minutes,
duration lasts more than 30 seconds

False labor and true labor
1.discomfort is characterized
as over the lower abdomen
and groin areas
2.without effect on dilation
of the cervix (not associated
with progressive dilation )
3.typically shorter in
duration
4.less intense
5.relieved by administration
of a sedative or ambulation
1.over the uterine
fundus,with radiation of
discomfort to the low
back and low abdomen.
2. Associated with
effacement and dilation
3. Increasingly intense and
frequent
4. Regular and effective

Essential factors of labor(1)
The progress and final outcome of labor are influenced by 4
factors:
1) the labor force
2) the passage (the bony and soft tissues of the maternal
pelvis)
3) the passenger (fetus)
4) the psyche.
Abnormalities of any of these components, singly or in
combination, may result in dystocia.

PHYSIOLOGY OF NORMAL
LABOR
• Uterine contractions in labor :Painless
BHC.
• The character of the contractions changes
with onset of labor.The pacemaker is
situated in tubal Ostia from where waves of
contractions spread downwards.
• Good synchronization of the contraction
waves both havlesof uterus.

• Fundal dominance
• Waves follow regular pattern.
• Upper segment contracts more.
• Intraamniotic pressure rises beyond
20mmHg.
• Good relaxation occurs.
• During contractions uterus becomes hard
,makes long axis anteriorly.patient feels pain
in hypogastric region radiating to thighs.

• Tonus :intrauterine pressure in between
contractions 8 to 10mmHg.
• Intensity :100mmHg-in 2nd stage of labor.
• Duration :30 seconds
• Frequency :intervals of 10-15 min
• Retraction :it is the phenomenon of uterus
in labor in which muscle fibres are
shortened permanently.

Mechanism in initiation of labor.

Uterine contraction.
Labor force Abdominal muscle.
Levator ani muscle
Bony canal (pelvis) (no change)
Birth canal vulvar, vagina, cervix,
Lower uterine segment
Fetal position
Fetus
Fetal size
Psychic factors. A high level of anxiety during pregnancy has
been associated with decreased uterine activity and with
longer and dysfunctional labor.

LABOR FORCE
1) Uterine contraction.
It is the major force through the whole course of
labor. It includes contraction and retraction.
There are three effective features.
Rhythmy and Intermittent
Dominance and pacemaker
Retraction.

LABOR FORCE-uterine contraction
(1) Dominance and pacemaker
Uterine contraction in labor (patterns of contraction)
there is good synchronisation of the contraction waves of
both halves of the uterus.
The pacemaker of uterine contractions is probably
situated in the region of the cornu from where waves of
contraction spread downwards.

LABOR FORCE

LABOR FORCE
• Electrical traces of the pattern of uterine
contraction show that in normal labor each
contraction wave starts near one or other
uterine cornu. The contraction spreads as a
wave in the myometrium, taking 10-30 seconds
to spread over the whole uterus.

LABOR FORCE
Dominance : The upper segment contracts more
strongly than the lower part, and the duration
is longer than in the lower segment, this
dominance of the upper segment leads to the
stretching and thinning of the lower segment
and to dilation of the cervix.

LABOR FORCE
• (2) The contractions are regular and
rhymic.

LABOR FORCE
After contractions there is a intermittent. As
labor progress, the intensity increase,
frequency increase, contractile duration
prolong and intermittent shorten gradually, by
the end of the first stage of labor the
contraction may come every 1 to 2 minutes and
may last as long as a minute.

LABOR FORCE
• Intermittent :
The intermittent nature of the contractions is of great
importance to both the fetus and the mother. During a
contraction the circulation to the placental bed through the
uterine wall is stopped; if the uterus contracted continuously
the fetus would die from lack of oxygen. The intermittent
allow the placental circulation to be re-established and give
the mother time to recover from the fatigue effect of the
contraction. The uterus is a large muscle and contractions
use up a lot of energy, if continued too long this would
produce maternal exhaustion.

Essential factors of labor
LABOR FORCE
uterine contraction include three parts:
intensity
duration
frequency

LABOR FORCE
• Intensity of contraction: it describes the degree of uterine
systole. The intensity gradually increases with advancement
of labor until it becomes maximum in the second stage during
delivery of the baby. During the first stage intrauterine cavity
pressure is raised to 40-50mmHg and during second stage it is
raised about to 100-120 mmHg.
Frequency: in the early stage of labor, the contraction
come at intervals of 10-15 min. The intervals gradually
shorten with advancement of labor until in the second stage,
when it comes every one or two minutes.

LABOR FORCE
Duration: in the first stage, the contraction
lasts for about 30-40 seconds initially but
gradually increases in duration with the
progress of labor. Thus in the second stage, the
contractions last longer than in the first stage.

LABOR FORCE-- retraction
• Uterine contraction and retraction is
throughout the full labor. The uterus not only
contract but also retract. The dilation of the
cervix, descent of presenting part and progress
of labor depend on the uterine contraction and
retraction.

• Retraction: retraction is a phenomenon of the uterus in
labor in which the muscle fibres are permanently shortened,
it is different from the contraction.
Retraction is specially a property of upper uterine
segment. Contraction is a temporary reduction in length of
the fibres, which attain their full length after the contraction
passes off. In contrast, retraction results in permanent
shortening and the fibres are shortened once and for all.
When the active contraction passes off the fibres
lengthen again, but not to their original length.

If contraction was followed by complete relaxation no
progress would be made, in retraction some of the shortening
of the fibres is maintained. So the uterine cavity becomes
progressively smaller with each contraction.
The net effect of retraction in normal labor are:
-- essential property in the formation of lower segment and
dilation and taking up of the cervix
-- to maintain the advancement of the presenting part made
by the uterine contraction and to help in ultimate expulsion of
the fetus
-- to reduce the surface area of the uterus favouring separation
of placenta

LABOR FORCE
• Abdomenal muscle and
diaphram .
• In second stage,delivery of the
fetus is accomplished by the
downward thrust offered by
uterine contractions
supplemented by voluntary
contraction of abdominal muscles
against the resistance offered by
bony and soft tissues of the birth
canal.
• Help fetus and placenta delivery
in the second stage and third stage.

LABOR FORCE
• the expulsive force of uterine contraction is added by
voluntary contraction of the abdominal muscles called
“bearing down” efforts.
• Pelvic floor (levator ani muscle.) Help fetus
internal rotation

birth canal The bony canal
The bony canal means true pelvis, its size and
shape is relation with delivery closely. There three
plane.
Pelvic inlet plane. The true conjugate describe the
anteroposterior dimension of the inlet, it is average
11cm. The transverse diameter of the inlet is average
13cm. An oblique diameter is average 12.75cm.

birth canal
Pelvic midplane. it is the smallest plane of the
pelvic canal. Its anteroposterior diameter is average
11.5cm. its transverse diameter between the ischial
spines( interspinous diameter) is average 10cm
The plane of least dimensions is an important
obstetric plane because shortening of its diameters
frequently is associated with obstructed labor.

birth canal
pelvic outlet plane. The plane of the
pelvic outlet is actually two triangular
planes at different inclinations that share the
same base. The transverse diameter,
between the inner margins of the ischial
tuberosites, average 9cm.
• pelvic axis and inclination of pelvis

birth canal
The soft birth canal
The formation of lower segment.
• Before labor begins, the uterine body appears to be
a single unit. However, uterine contractions soon cause
it to differentiate into visibly different upper and lower
segments.
• The upper segment is actively contractile, thick, and
powerful. The lower segment is passive, thin, and
distensible.
• The physiologic retraction ring separates the two
segments.

birth canal

birth canal
This powerful segment draws the weaker, thinner
and more passive lower segment up over its contents, and
in so doing pulls up and then dilates the cervix.
The wall of the upper segment becomes progressively
thicker with progressive thinning of the lower segment.
This is pronounced in late first stage, specially after
rupture of the membranes and attains its maximum in
second stage.
A distinct ridge is produced at the junction of the
two segments, called physiological retracting ring.

birth canal
• The change of cervix
After cervical effacement ,dilation of cervix
begins in primigravidae.
But in multiparae the effacement and dilation
occur together.

birth canal
During labor as the cervix dilated and the lower
segment is drawn up, its shape changes from a
hemisphere to a cylinder.
The musculature of the lower segment stretches to
permit more and more of the intrauterine contents to
fit within it and to distend its walls.
In labor the lower segment, cervix,vagina, pelvic
floor and vulval outer are dilated until there is one
continuous birth canal.

birth canal
The forces which bring about this dilation and expel
the fetus are supplied mostly by the muscle of the
upper uterine segment, with some assistance in the
second stage from the abdominal muscles, including the
diaphragm.

birth canal
The change of vagina and perineum

Essential factors of labor--fetus

Stages of labor (1)
Although labor is a continuous process, it
is divided into three functional stages:
first stage ------ dilation of cervix
second stage ----- fetus delivery
third stage -------- placenta delivery
fourth stage ------- within 2h after delivery

Stages of labor(2)
• First stage: it starts from the onset of true labor pain
and ends with full dilation of the cervix. 8-12 hr
The first stage is further divided into two phases, the
latent phase and the active phase.
In the latent phase, cervical dilation is under 3 cm,
the contractions may be infrequent, are usually not
more than moderately strong and the patient can
tolerate, in active phase, more rapid cervical dilation
occurs,usually beginning at approximately 3cm .

Stages of labor(3)
Second stage: (giving birth): it starts from the full
dilation of cervix and ends with expulsion of the fetus
from the birth canal. Its duration is 1-2 h in
primigravidae, 30 minutes in multiparae.
Third stage: it begins immediately after delivery of the
infant and ends with the delivery of the placenta. Its
average duration is about 15 minutes in both
primigravidae and multiparae.

Stages of labor(4)
• Four stage: (after deliver of baby and placenta,
observing uterus and bleeding)
it is defined as the immediate postpartum period of
approximately 2 hr after delivery of the placenta.
During this time the patient’s general condition and the
behavior of the uterus are to be carefully watched.
The maidwife monitors the amount of blood as well as
pulse and blood pressure in the first several hours after
delivery to identify excessive blood loss.

Clinical features and management of
the stage (1)

In the first stage
1. Events of the first stage
(1) Cervical effacement and dilation
Effacement of the cervix is a process of thinning
out which is accomplished during first stage of
labor or even before that in primigravidae. Taking
up is effected by retraction. Expulsion of mucus
and the compression effect also help in thinning of
the cervix.

In the first stage
The degree of cervical effacement is expressed as
percent effacement.
i.e. A cervix that is thinned to one-half of its
original 2cm length is termed 50%,whereas a cervix
that is virtually totally thinned is described as 100%
effaced. The dilation of cervix is described as
centimeters of dilation. Fig .

In the first stage
• (2) formation of uterine segment

In the first stage
2.Clinical features (1)
(1) Pain---- come from the intermittent uterine
contraction initially, the pain are not strong enough
to cause discomfort and come at varying intervals
of 15-30 min with duration of about 30 seconds.
But gradually the interval becomes shortened
with increasing intensity and duration so that in
late first stage the contraction comes at intervals of
2-3min and last for about 50-60 seconds.

In the first stage
(2) Fear --- although the patient may have undergone
some education regarding the labor and delivery
process, it is important to realize that the patient
has significant fear that remain.
A support person may be allowed to remain
with the patient throughout the labor and delivery
process in most cases. At no time in labor should
the women be left alone. The partner should be
with all the time, and midwife as much as possible.

In the first stage
• (3) Micturation--- during the course of labor,
descent of the fetus causes the bladder to be
elevated relative to the lower uterine segment
and cervix. this often results in the patient
having difficulty voiding. The patient, therefore,
be encouraged to void frequently.
Catheterization may become necessary if the
bladder becomes distended

In the first stage
(4) Diet --- during labor there is delay in the
emptying time of the stomach and food or
fluids may remain there for several hours.
Solid food should be avoid intake. The diet
should be liquid with sufficient food value and
pleasant to take.

In the first stage
(5) Dilation and taking up of the cervix --- by vaginal and
rectum examination the dilation and taking up is found.
Cervical dilation is expressed in terms of centimeters. It is
usually measured with fingers but recorded in centimeters.
One finger equals to 1.6 cm and when the dilation is
more than 6 cm, it is easier to subtract twice the width of
the remaining ‘rim’ from 10 cm to measure the actual
dilation.

In the first stage
2. Management (1)
1) admitted to hospital
reasons: a. if their contractions occur
approximately every 5~10 min for at least 1 hr
b. If there is a sudden gush of fluid or a
constant leakage of fluid
c. if there is any significant bleeding
d. If there is significant decrease in fetal
movement

In the first stage
2. Management (2)
2) evaluation for labor
a. taking history in detail and review perinatal
records
(LMP, EDC,vaginal bleeding, infectious
disease,...)
b. A limited general physical examination is
performed. Pay special attention to vital signs.

In the first stage
2. Management (3)
c. Abdominal examination:
The initial examination of the gravid abdomen may
be accomplished using Leopold maneuvers, a series of
four palpations of the fetus through the abdominal wall
that helps accurately determine fetal lie, fetal
presentation, and fetal position. The fetal heart rate is
checked and any abnormality of rate or rhythm is noted.

In the first stage
2. Management (4)
d. Vaginal examination: (dilation and station)
• the vaginal examination should be performed using an
aseptic technique, in the presence of significant bleeding , the
vaginal examination should be done with extreme care. Before
any digital examination a sterile speculum examination
should be performed.
The digital portion of the vaginal examination allows the
examiner to determine the degree of cervical effacement. The
cervix is also palpated for cervical dilation described as
centimeters of dilation. The examiner uses one or two fingers
to identify the diameter of the opening of the cervix.

In the first stage
2. Management (5)
• Fetal station is also determined by identifying the
relative level of the foremost part of the fetal presenting
part relative to the level of the ischial spines. If the
presenting part has reached the level of the ischial
spines, it is termed “0” station.

In the first stage
2. Management (6)
• Spines are the most prominent bony projections
felt on internal examination and the bispinous
diameter is the shortest diameter of the pelvis in
transverse plane 10-10.5cm, the station is said to
“0” if the presenting part is at the level of the
spines. The station is stated in minus figures, if it
is above the spines (-1,-2,-3 and floating ) and in
plus figures if it is below the spines (+1,+2,+3 and
on the perineum).

In the first stage
2. Management (7)

In the first stage
2. Management (8)
The following information are to be noted and recorded
carefully when performing vaginal examination:
( 1) degree of cervical dilation in centimeters
( 2) degree of effacement of cervix
( 3)status of membranes and if ruptured-color of the
liquor
( 4) presenting part and its position by noting the
fontanelles and sagittal suture in relation to the
quadrants of the pelvis
( 5) station of the head in relation to ischial spines

In the first stage
2. Management (9)
3) Partogram (Two main contents)
Once labor has become established, or the membranes have
ruptured, all events during labor should be noted on a partogram.
it is a most useful graphical record of the course of labor.
Routine observations of the woman’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 dilation of the
cervix in centimeters against the time in hours. If the woman’s
progress is normal her curve will correspond with the normal curve,
or lie to the left of it.

In the first stage
2. Management (10)
4) Fetal monitoring
The fetal heart rate is counted with a stethoscope at half hourly
intervals in early labor and at 10 min intervals in the active phase
of labor.
The normal rate 120 ~ 160 beats per minute and there is no
change of rate, or only a very transient showing, with the uterine
contractions.
Most hospital have employed fetal monitoring during labor, the
uterine contractions can be recorded .

In the first stage
2. Management (12)
5) relief of pain
Towards the end of the first stage the pains become
more severe. The epidural analgesia should be
employed.
If it is not employed, drugs such as pethidine 100mg
intramuscularly may be given if the woman is
distressed

In the first stage
2. Management (13)
In the first stage the principle is:
(1) non-interference with watchful expectancy so
as to prepare the patient for a smooth delivery in the
second stage.
(2) to monitor carefully the progress of labor,
maternal conditions and fetal behavior so as to detect
any deviation from the normal at the earliest possible
moment.

In the second stage
Events of the second stage
• This stage is concerned with the descent and
delivery of the fetus through the birth canal.

In the second stage
clinical features
• painful contraction is stronger and more frequent;
• bearing birth efforts: the expulsive force of uterine
contraction is added by voluntary contraction of the abdominal
muscles called “bearing down” efforts. In majority, the pushing
down efforts start just prior to full dilation of the cervix. It is of
immense help in accelerating the expulsion of the fetus.
At the height of uterine contraction, the woman closes her
glottis, holds her respiration at the height of inspiration,clutches
whatever is available and voluntarily contracts the abdominal
muscles in an attempt to expel the fetus out of her womb. The
face becomes flushed, the neck veins are prominent, the pulse rate
is rapid and there is perspiration.

In the second stage
clinical features
• descent of fetal head---features of descent
of the fetus are evident from abdominal and
vaginal examination.
• Vaginal signs:as the head descends down, it distends
the perineum, the vulval opening looks like a slit through
which the scalp hairs are visible. During each contraction,
the perineum is markedly distended with the overlying skin
tense and glistening and the vulval opening becomes
circular.

In the second stage
clinical features
• Vaginal signs: the adjoining anal sphincter is
stretched and stool comes out during contraction. The head
recedes after the contraction passes off but is held up a
little in advance because of retraction. Ultimately, the
maximum diameter of the head stretches the vulval outlet
and there is no recession even after the contraction passes
off. This is called the crowning of the head.

In the second stage
clinical features
• The perineum, including the anal sphincter,
is very much stretched and the anterior
rectal wall is visible. The head is born by
extension. After a little pause, the mother
experiences further pain and bearing down
efforts to expel the shoulders and the trunk.

In the second stage
clinical features
• Maternal signs: there are features of exhaustion.
Respiration is slowed down with increased perspiration.
During the bearing down efforts, the face becomes
congested with neck veins prominent. Immediately
following the expulsion of the fetus, the mother heaves a
sigh of relief.
• Fetal signs: bradycardia during contractions is very
much prominent which often continues because of quick
successive contractions.

In the second stage
management
• Principles:
To assist in the natural expulsion of the fetus slowly
and steadily
To prevent perineal injuries
• Preparation for delivery ( dorsal position,
catheterise the bladder)
• Conduction of delivery: delivery of the head, delivery
of the shoulders, delivery of the trunk

Once the head is crowned the woman should be
discouraged from bearing down by telling her to take rapid
shallow breaths. The head may now be delivered carefully by
pressure through the perineum onto the fore part of the head
by means of a finger and thumb placed on either side of the
anus, pushing the head forwards slowly before it is allowed to
extend and complete its delivery and controlling the rate of
escape with the other hand.
The left hand is preventing sudden expulsion of the head,
while the fingers and thumb of the right hand are gently
helping the head forwards by pressure on each side of the
anus.

In the second stage
management
Delivery of the head--- to maintain flexion of the head, to
prevent its early extension and to regulate its slow escape
out of the vulval outlet.

In the second stage
management
• delivery of the shoulders,

In the second stage
management
• Delivery of the trunk: after the delivery of
the shoulders, the fore finger of each hand
are inserted under the axillae and the trunk
is delivered gently by lateral flexion.

• The mouth and pharynx are sucked clear with
a mucus extractor, a healthy baby breathes and
cries very soon after it is born, if it fails to do so
the baby needs active resuscitation. Normally
the cord should not be clamped until the child
has cried vigorously and pulsation in the cord
has ceased.
So in the second stage the principle is (1) to
assist in the natural expulsion of the fetus
slowly and steadily,(2) to prevent perineal
injuries.

In the third stage
• The third stage of labor comprises the phase of placental
separation, its descent to the lower segment and finally its
expulsion with the membranes
Placental separation : At the beginning of labor, the
placental attachment roughly correspond to an area of 20 cm
in diameter. During the second stage, there is slight but
progressive diminution of the area following successive
retractions, which attains its peak immediately following the
birth of the baby.

In the third stage
• Mechanism of separation: marked retraction
reduces effectively the surface area at the placental
site to about its half. But as the placenta is
inelastic, it cannot keep pace with such an extent
of diminution resulting in its buckling.
A. Central separation
B. margnal separation

In the third stage
events
• Expulsion of placenta: after complete separation of
the placenta, it is forced down into the flabby lower uterine
segment or upper part of the vagina by effective
contraction and retraction of the uterus. Thereafter, it is
expelled out by either voluntary contraction of abdominal
muscles or by manipulative procedure.

In the third stage
clinical features
• Pains: for a short time, the patient experiences no pain.
However, intermittent discomfort in the lower abdomen
reappears, corresponding with the uterine contraction.
• Before separation:
per abdomen--- discoid, firm,funds below the umbilicus,
per vagina--- slight trickling of blood,length of cord as
visible from outside, remains static.

In the third stage
clinical features
• After separation
per abdomen--- uterus becomes globular,firm.the
fundal height is slightly raised as the separated placenta
comes down in the lower segment and the contracted
uterus rests on top of it.
per vagina--- there may be slight gush of vaginal
bleeding. Permanent lengthening of the cord is established.

In the absence of an effective epidural block,
full dilation of the cervix is accompanied by a
bearing down sensation during contractions and
women are then usually encouraged to push, as the
contraction comes on the woman takes a deep
breath, then holds it and subsequently bears down
with all the force of her abdominal muscles, these
partly voluntary, partly reflex expulsive efforts
place the fetus under additional stress and pushing
should therefore not be allowed to continue for
more than one hour.

The progress of the descent of the head can be
judged by watching the perineum. At first there is
a slight general bulge as the woman strains.when
the head stretches the perineum the anus will
begin to open, and soon after this the caput will be
seen at the vulva at the height of each contraction.
Between contractions the elastic tone of the
perineal muscles will push the head back into the
cavity of the pelvis. ----- head visible on vulval
gapping .
The perineal body and vulval outlet become
and more stretched until eventually the head is low
enough to pass forwards under the subpubic arch.

When the head no longer recedes between
contractions this indicates that it has passed through
the pelvic floor and that delivery is imminent. The
maximum diameter of the head (biparietal) stretches
the vulval outlet and there is no recession even after
the contraction passes off. This is crowning of the head.
Laceration of the perineum often occurs during
birth of the head. By the time the head begins to
appear at the vulva.
At this stage the midwife or doctor must control the
head to prevent its being born suddenly and it must
be kept flexed until the largest diameter has passed the
vulval outlet.

• In order to prevent from perineal rupture, if is
important that the head should be born slowly and in
an interval between contractions. Episiotomy,or
incision of the perineal body sometimes is necessary.
• The shoulders usually follow with the contraction
following the birth of the head, the anterior shoulder
being delivered before the posterior. The shoulders
can cause damage unless they are carefully delivered.
After delivery of the shoulders the rest of the body
quickly follows, as soon as the child is delivered it is
held with its head downwards so that any fluid or
mucus in the mouth can run out.

• After the birth of baby, the uterus measures about
20 cm vertically and 10 cm anteroposteriorly, the
shape becomes discoid, the wall of the upper
segment is much thickened while the thin and
flabby lower segment is thrown into folds. The
cavity is much reduced to accommodate only the
after-births.
• Mechanism of separation: marked retraction
reduces effectively the surface area at the placental
site to about its half. But as the placenta is
inelastic, it cannot keep pace with such an extent
of diminution resulting in its buckling.

• Before separation: uterus becomes discoid in
shape, firm in feel and non-ballottable, fundal
height reaches slightly below the umbilicus. There
may be slight trickling of blood. Length of the
umbilical cord as visible from outside, remain
static.
• After separation: it takes about 5min in
conventional management for the placenta to
separate. Uterus becomes globular, firm and
ballottable, the fundal height is slightly raised as
the separation placenta comes down in the lower
segment and the contracted uterus rest on top of it.

• There may be slight gush of vaginal
bleeding. Permanent lengthening of the cord
is established. Then the expulsion is
achieved either by voluntary bearing down
efforts or more commonly aided by
manipulative procedure.

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