Normal Labour

NORMAL LABOUR
Dr. Poly Begum
Assistant Professor
Diabetic Association Medical College
Faridpur
12/10/16Dr. Poly Begum 1

Definition of labour:-
 series of events that take place in the
genital organs in an effort to expel the
viable fetus out of the uterus through the
vagina in to the outer world.
Definition of delivery:-
Is the expulsion or extraction of a viable
fetus out of the uterus.

Normallabour
 Labour is normal when it is
1. Spontaneous in onset
2. At term
3. single fetus
4. vertex presentation
5. Without undue prolongation
6. With no maternal complications or
7. Fetal complications
- Any deviation from this definition is abnormal

Onset of labour
 Based on naegel’s formula labour starts
approximately as follow.
 In the expected date of delivery in 4% of
cases
 One week on either side in 50% of cases
 Two weeks earlier and one week later on
80% of cases
 At 42 weeks in 10% of cases
 At 43 weeks plus in 4% of cases

Causes of the onset of labour
 Unknown the following theories were
postulated
1. Optimal distension theory
- When the uterus is distended to a certain
limit, it starts to contract to evacuate its
contents (multiple preg. Polyhydramnios)
2. feto- placental theory
- Due to unknown factors fetal pituitary is
stimulated with increase release of ACTH
that stimulate the

fetal adrenal to produce cortisol which
act in the placenta to produce
estrogen and prostaglandins.
3- estrogen theory:-
during the last trimester more free
estrogen appears increasing the
excitability of the myometrium and
prostaglandin synthesis

4- progesterone:
 Increase fetal production of dehydroepiandro-
sterone sulphate with cortisol may inhibit the
conversion of fetal pregnenolone to progesterone
there by altering the estrogen progesterone ratio.
5- prostaglandins:-
- Attracted much attention in recent years produced
by-placenta –membrane –decidual cells and
myometrium

Synthesis is triggered by
 Rise in estrogen level
 Altered estrogen. Progesterone ratio
 Mechanical stretching in later pregnancy
 Infection or separation of membranes
↑ oxytocin receptors
6. Oxytocin theory:-
although oxytocin is a powerful stimulator of
uterine contraction its natural role in onset of
labour is doubtful .

LABOUR AND DELIVERYLABOUR AND DELIVERY
Prof DR MOHD AZHAR – “NOMAL LABOUR & DELIVERY
FACTORS THAT INFLUENCEFACTORS THAT INFLUENCE
PROGRESS OF LABOURPROGRESS OF LABOUR
Passenger Passage
Power

THE NORMAL FEMALE PELVIS
1. The female pelvis provides the basic framework of the
birth canal.
2. The obstetric pelvis is divided into false and true pelvis
by the pelvic brim or inlet
3. The true pelvis is important, for it is through this
confined space that the fetus must pass on its journey
through the birth canal.
4. The true pelvis is composed of inlet, cavity and outlet.
5. Types of female pelvis – gynaecoid, anthropoid,
android and platypelloid
Outlet
Cavity
Inlet

THE NORMAL FEMALE PELVIS
1. The brim is slightly oval transversely.
2. The sacral promontory is not prominent.
3. The transverse diameter is slightly longer
than the anteroposterior.
4. The sidewalls are parallel and straight.
5. The ischial spines are not prominent.
6. The sacrosciatic notches are wide.
7. The sacrum has a good curve.
8. The pubic arch angle are wide, i.e. more than
90°
9. Inter tuberous diameter is wide
The ideal normal female gynaecoid pelvis:

THE NORMAL FEMALE PELVISTHE NORMAL FEMALE PELVIS
The important diameters of the female pelvis:
AnteroposteriorAnteroposterior ObliqueOblique TransverseTransverse
BRIMBRIM 11 – 11.511 – 11.5 1212 12.512.5
CAVITYCAVITY 1212 1212 1212
OUTLETOUTLET 12.512.5 1212 11- 11.511- 11.5
DiametersDiameters
(cm)(cm)

THE FETAL SKULLTHE FETAL SKULL
1. Sutures
2. Diameters

1. Sagittal suture: - The sagittal suture lies between the
parietal bones. It runs in an anteroposterior direction
between the anterior and posterior fontanelles.
2. Coronal sutures: - The suture uniting the parietal bones
to the frontal bones is called the coronal suture. It’s
extend transversely from the anterior fontanels and lies
between the parietal and frontal bone.
3. Frontal suture: - The frontal suture is between the two
frontal bones. It is an anterior continuation of the
sagittal suture.
4. Lambdoidal suture: - Is between the parietal and
occiptal bones.
SUTURES

MOULDING OF THE FETAL SKULL
MOULDING’ is the ability of the fetal head
to change its shape and so to adapt itself
to the unyielding maternal pelvis during
the progress of labour.
This property is of the greatest value in the
progress of labour.

Diameters of the fetal skull – anterior posterior diameters
A
B
C
D
E
F
G
AB ~ Suboccipto bregmatic – 9.5
AC ~ Submento bregmatic – 9.5
DE ~ Occipito frontal ~ 11.0
FG ~ Mento vertical – 13.5

POWERPOWER ►► Contractions + Maternal
pushing
Uterine contractions:
1. Initiate by pacemakers ~ uterotubal junction
2. Contraction waves meet at the fundus
3. Contraction waves progress downward
 Shortening of muscle fibres
 Retractions
 intra uterine pressure
EXPULSION OF THE FETUS
Additional force
“maternal pushing”
Intra abdominal pressure

UTERINE CONTRACTIONUTERINE CONTRACTION
NORMAL CONTRACTION
1. Frequency ~ one in every 2 – 3 min with at least 1 minute interval
2. Intensity ~ strong (> 50 mmHg)
3. Duration ~ 45 – 60 sec
Uterine contractions

Diagnosis of labour :-
Pre labour (premonitory stage :-
- May begins two to three weeks before the
onset of true labour in PG. and few days
before in multi gravida and may consist of
the following .

1)Lightening :- A sense of relief from the
upper abdominal pressure symptoms such as
dyspnoea or dyspepsia due to sink of the
presenting part into the true pelvis .
2.Pelvic pressure symptoms such as frequency
of micturition due to engagement of the
presenting part .
3.Cervical changes (ripening of the cervix)
become soft , less than 1.3cm in length
,Admit tip of the finger and is dilatable .
4.Appearance of false pain .

True Labour

Features of true labour are :-
1) Labour pain:-
- Intermittened painful and regular .
- Increase progressively in frequency,
duration and intensity .
- Felt in the abdomen and radiate to the back
and thigh .

2)The show Expulsion of the cervical mucus
plug mixed with blood –may occur few days
before the onset of labour .
3) Progressive effacement and dilatation of
the cervix .
4) Formation of the bag of forewater ,the
lower pole of the fetal membranes become
unsupported and tend to bulge through the
cervical canal .

Stages of labour
 Labour is divided into four
stages:-
1- First stage of labour:-
- It is the stage of cervical
dilatation .
- Starts with the onset of labour
pain and ends with full
dilatation of the cervix .
- It takes about 12 hours in a
Primipara, and 8hrs in a
multipara .
- It’s composed of two phases .

A) Latent phase:
Starts from the onset of labour and
ends when the cervix is (2 to3 cm)
dilated . It occurs because the
thinning of the lower segment and
cervix take a lot of uterine work
before rapid dilatation can begin .
It takes about (6 to 8 hrs) .

B) Active phase :-
It is the phase of rapid dilatation of the cervix
from 3cm dilatation up to full dilatation it
also take (6hrs) with a rate of cervical
dilatation of (1.2cm/hour)in PG and
(1.5cm/hour)in multigravida .
It has three components:-
i) Accelerated phase of dilatation from
(2.5cmto4cm).
ii) Phase of maximum slope of (4to9cm) dilatation
iii) Phase of deceleration of (9-10cm) dilatation .

Causes of cervical dilation:-
1. Contraction and retraction of uterine
musculature (primary force)
- Normal uterine contraction occur with
frequency of one every 2-3 minutes with
at least 1min between contraction. With
a duration of 40-70 seconds and an
intensity of around 50 mmHg & a resting
tone less than 15 mmHg

 The contraction begins in two pace makers
near the utrotubal junction –only one pace
maker is operative in each contraction. It
spread like a wave over the whole uterus-
strong in the funds (fundal dominance) less
strong in the mid zone and relatively in the
lower segment.
 Relaxation begins simultaneously in all areas
of the uterus.
 The force generated by each contraction is
applied to the amniotic fluid and directly

Against the pole of the infant that occupies the
upper segment therefore each time the muscle
contracts the uterine cavity becomes smaller
and the presenting part or the fore bag of
water lying a head of it is pushed down ward in
to the cervix this tends to force it to open or
dilate.
 A more potent factor in cervical dilatation
however is the retraction of the upper
segment. As this area of the uterus becomes
shorter and thicker it pulls the lower segment
and the dilating cervix upward around the
presenting part at the same time the

uterus contracting directly against the
infant tends to push it through the
cervical opening .
Cervical dilatation in primigravida
occurs from above down ward
causing progressive shortening of
the cervix.( effacement).
In multigravida effacement and
dilatation occurs simultaneously.

2. Second stage of labour
 It is the stage of expulsion of the fetus
 Begins with full cervical dilatation and ends
with delivery of the fetus
 Its duration is about one hour in
primigravida and ½ an hour in multigravida.
 Delivery of the fetus is affected in addition
to the uterine contraction( primary force)
by voluntary contraction of the abdominal
muscles with the diaphragm fixed after
forced inspiration .

This will increase intra abdominal pressure
(secondary force).
 This secondary forces have no effect on
cervical dilatation but they are of
considerable importance in aiding the
expulsion of the infant from the uterus
and vagina after the cervix is completely
dilated.

3- third stage of labour:-3- third stage of labour:-
comprises the phase of placental separationcomprises the phase of placental separation
its descent to the lower segment and finallyits descent to the lower segment and finally
its expulsion with the membrane.its expulsion with the membrane.

 It begins after delivery of the fetus and end
with expulsion of the placenta and
membrane.
 Duration is about 10__20 minutes in both
primigravide and multigravida.
 Placental separation is due to marked
uterine muscle retraction which reduces the
surface area at the placental site to about
its half but as the placenta is inelastic a
shearing force in instituted bringing about
its separation. the plane of separation runs
through the deep spongy

Layer of the decidua basalis
 There are two mechanism of placental
separation.
1- central separation (Schultz) occur in 80% of
cases- detachment of placenta from its
uterine attachment starts at the centre.
2- marginal separation( Mathews –Duncan)
occurs in 20% of cases. Separation starts at
the margin as it is mostly un supported

 After complete separation of the placenta it is
delivered by effective uterine contraction and
retraction and expelled out by either voluntary
contraction of abdominal muscle (bearing
down effort) or by manipulative procedures.
 After placental delivery the uterine sinuses
and arterioles are occluded by effective
uterine contraction and retraction which is the
principle mechanism of haemostasis, however
thrombosis also occurs and is facilitated by the
hypercoagulable status of pregnancy.

4-fourth stage of labour
 Begins immediately after expulsion of
the placenta and membranes and last
for one hour.
 Careful observation of the patient for
signs of postpartum hemorrhage is
essential.

Mechanism of normal labour:-
 It refers to the series of changes in position
and attitude which the fetus under goes
during its passage through the birth canal
And it consist of the following.
1) Descent of the fetus is a continuous
movement it is slow or insignificant in the
first stage of labour but pronounced in the
second stage. it is completed with the
expulsion of the fetus. It is due to contraction
and retraction of uterine muscle (primary
force). Added in the second stage by bearing
down efforts (secondary force).

2- flexion:-
As the head meet the resistance of the
birth canal during descent full flexion
is achieved to bring the shortest sub-
occipito bregmatic diameter. Of the
head(9.5cm).
Flexion is essential for descent since it
reduces the shape and size of the
plane of the advancing diameter of the
head.
 12/10/16Dr. Poly Begum 40

3- internal rotation
In the second stage of labour the forces propel
the fetus progressively down the birth canal,
when the head meets the resistance of the
pelvic floor the occiput rotates forward to lie
under the sub pubic arch with the sagittal
suture in the antero-posterior diameter of
the pelvic out let . This internal rotation of
the head occurs because with a well flexed
head the occiput is leading and meets the
slopping gutter of the

Lavatores ani muscles which by their shape
direct it anteriorly.
4. extension:-
 further advances of the head lead to its
passage through the vulva by a process of
extension. Once the occiput has escaped
from under the symphysis pubis the head
extends with the nape of neck pressed
firmly against the public arch. The
successive parts of the fetal head to born
through the stretched vulval .out let are
vertex , brow and face.

5- restitution:-
As soon as the head is completely born
it resumes its natural position with
regard to the shoulders by rotating 1/8th
of a circle in the direction opposite to
that of internal rotation. The neck
becomes untwisted and the head is
restored to its natural relation to the
shoulder.

6. External rotation
 It is the movement of rotation of the head
visible externally due to internal rotation of
the shoulders it carries the head in a
movement through 1/8th
of a circle in the same
direction as restitution.
7- Birth of shoulders and trunk:-
- Further descent takes place the anterior
shoulder escapes below the symphysis pubis
and by lateral flexion of the spine the
posterior shoulder sweeps over the perineum.
Rest of the trunk is there expelled out

Management of normal labour
First stage:-
 On admission a complete history must be taken
 Antenatal record is reviewed to discover
whether there have been any abnormalities
during pregnancy
 The women general condition is assessed her
pulse-blood pressure and temperature are
recorded

 on abdominal examination the presentation
and position of 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 uterine contraction .
 The location, rate and regularity of the fetal
heart tones are also determined.
 A vaginal examination will show the degree of
cervical dilation, whether the membranes are
intact or rupture and the

Position with station of the presenting part.
 A urine specimen is examined for protein and
glucose and a hemoglobin or haematocrit
determination is made.
Enema:-
 It’s routine use is unnecessary and has no
particular benefit.
 Usually given early in the first stage of labour
to empty the rectum to prevents soiling of the
perineum during the second stage.

 Shaving or clipping of the vulval
hair
 Is not necessary
 Awarm bath or shower is both hygienic and
pleasant.
 Rest:-
 there is no need for the women to remain
in bed during early labour. She is allowed to
walk about and to sit. This attitude prevents
venacaval compression and encourage
descent of the presenting part.

Oral intake
 The major risk to be avoided is aspiration of
gastric contents, this only occurs in the context
of general anesthesia.
 Intake of solid food must be avoided, low fat,
low residuce food and drink can be given.
 If dehydration needs to be corrected normal
saline should be infused.

Bladder care:-
 The patient should be encouraged to empty her bladder
frequently as full bladder often inhibits uterine
contraction.
 If the patient fails to pass urine specially in late first stage
catheterization is to be done with strict aseptic
precaution.
Relief of pain:-
 Pethidine (100) mg intramuscularly can be given when the
pains are well estabished. It.

should not be given if delivery is anticipated
within two hours
 Epidural analgesia is very effective & do not
cause depression of fetal respiration
 If epidural is not used towards the end of first
stage a mixture of nitrous oxide & Oxygen
(Entonox) may be started with the onset of
each contraction.
Partogram:-
 One labour has become established all events
during labour should be recorded on the
partogram.

 Cervical dilatation marked in centimeters at
the time of admission to ward and at every
subsequent examination(2 hourly)
 Descent of head (in cm above or below the
lschael spine).
 Frequency, duration and strength of uterine
contration in (10)min. each half an hour.
 Fetal heart rate every ½ an hour.
 Condition of liquor and time and manner of
membranes rupture.
 moulding of the fetal skull

 Dosage of Oxytocin if used
 Maternal status (BP- pulse- temp-urinalysis).
 Medication (including epidural block if used

Management of the
second stage:-
 The transition from the first stage to the second
stage is evidenced by the following features.
- Appearance of bearing down efforts
- Complete dilatation of the cervix on vaginal
examination.
Principles of management are:-
1. To assist in the natural expulsion of the fetus slowly

2- to prevent perineal injuries
 General measures:
o FHR every 5 minutes
o Maternal pulse and blood pressure every
15mins
o If epidural block is not used to administer
inhalation analgesia (entonox) to relieve pain
during contraction
o Vaginal examination to confirm the on set of
the second stage – to detect cord prolapse and
to know the position and station of the head
o Nothing is given by mouth

Preparation for delivery:-
 Bearing down efforts, bulging of the
perineum and gaping of the anal opening
during contraction signify that delivery is
imminent so the patient should be shifted
to the labour table
Position of the patient
Dorsal position is more widely preferred with
the thighs flexed and separated . Some
however prefer delivery in lateral or
lithotomy position

 Toileting the external genitalia and inner
Side of the thighs with cotton swabs soaked
in savlon . And the area is covered with
sterile sheet. Keeping only the external
genitalia uncovered
 The delivery attendant should scrub put on
sterile gown ,mask and gloves
 To catheterize the bladder if it is full.

Conduction of the delivery
 The patient is encourage to intensify the
bearing down efforts during contractions.
 When the scalp is visible for about 5cm
diameter flexion of the head is maintained
during contraction by pushing the occiput
down wards and back wards by using thumb
and index fingers of the left hand while
pressing the perineum by the right palm with
a sterile vulval pad. This process is repeated
during subsequent

contraction until crowing of the head occurs
(biparietal diameter stretches the vulval out let
without any recession of the head even after
the contractions is over).
 When the perineum is fully stretched and
threatens to tear specially in PG episiotomy is
done at this stage after prior infiltration with
10/ml of 1% lignocaine.
 Slow delivery of the head is accomplished by
pushing the chin with sterile gauze .by covered
fingers of the right hand placed over the
anococcygeal region

 While the left hand exerts pressure on the
occiput. the forehead, nose, mouth and the
chin are thus born successively over the
stretched perineum by extension.
 The mucus and blood in the mouth and
pharynx should be wiped with sterile gauze
or alternatively mechanical sucker may be
used.
 The neck is then palpated to exclude the
presence of any loop of cord if it is found it
should be slipped over the head or if it is
sufficiently tight it is cut in between two
pairs of kocher’s forceps.

 Wait for uterine contractions to come and for
the movements of restitution and external
rotation of the head to occur, the anterior
shoulder is born behind the symphysis. If there
is delay the head is grasped by both hands and
is gently drawn posteriorly until the anterior
shoulder is released from under the pubis. by
drawing the head in upward direction the
posterior shoulder is delivered out of the
perineum.
 After delivery of the shoulders the fore fingers
of each hand are inserted under the axillae and
the trunk is delivered gently by lateral flexion.

 Some delay in clamping and cutting the
umbilical cord probably is beneficial to the
infant. As much as a 75 to 100ml increase in
fetal blood volume can be anticipated.
 The infant is placed in a heated crib with its
head slightly lower than its body. Its air
passage should be cleared of Mucus by
sucker before vigorous respiratory efforts
are established.
 Apgar rating at 1 minute an at 5 minute is to
be recorded

 A sterile cotton thread is applied to
the cord 2.5cm away from the navel
& the cord is divided with scissors
about 1 cm beyond the ligature.
Episiotomy:-
 Defined as a planned surgical
incision of the perineum made to
increase the diameter of the vulval
outlet during childbirth
(perineotomy)

Types of episiotomy
 1-midline:-
the cut is made vertically from the
fourchette down towards the anus.
 Advantages of this incision are less blood loss,
is easier to repair, the wound heals quicker,
and less postpartum pain and dyspareunia.
The major disadvantage it carries a higher
risk to extend to involve the anal sphincter.
 2-mediolateral:-
 This incision starts in the midline of the
fourchette and then directed outwards to
avoid the anal sphincter

 management of the
third stage:
Two methods of management are currently in practice
1. Watchful expectancy:-
- In this management the placental separation and its
descent into the vagina are allowed to occur
spontaneously. When the features of placental
separation at its descent into

the lower segment are confirmed the patient
is asked to bear down simultaneously with
uterine contraction. The raised intra-
abdominal pressure is often adequate to
expel the placenta. If the patient fail to
expel the placenta. controlled cord traction
(Brandt- Andrews method) can be tried. The
palmer surface of the fingers of the left
hand is placed approximately at the
junction of upper and lower uterine
segment the body of the uterus is displaced
upwards and backwards towards the
umbilicus while by the right hand steady
tension is given in

Downwards and backward direction until the
placenta comes outside .
 Signs of placental separation:-
1. A show of blood appears as the uterus
contracts.
2. Lengthening of the cord
3. The fundus become globular in shape,
rises above the umbilicus, become
palatable.

2. Active management:-
 Is associated with reduced blood loss.
 I.V ergometrine or syntometrine (syntocinon
5 units +ergometrine 0.5mg) is given with
delivery of the anterior shoulder.
 The placenta is immediately delivered after
delivery of the baby by controlled cord
traction after insuring uterine contraction

 As soon as the placenta passes through the
introitus it is grasped between the hands and
twisted around and round with gentle traction
so that the membranes are stripped intact.
 The placenta and the membranes should be
examined following their expulsion
 Vulva-vagina and perineum are inspected
carefully for injuries and to be repaired if any.
the episiotomy is sutured. The vagina is
evacuated from blood clots . The area is
cleaned and a dry sterile vulval pad is placed.

 The maternal condition –pulse –blood
pressure. Behavior of the uterus and any
abnormal vaginal bleeding is to be watched
at least for one hour after delivery (fourth
stage of labour).
 When fully satisfied that the general
condition is good pulse and blood pressure
are steady the uterus is well contracted and
there is no abnormal vaginal bleeding the
patient is sent to the ward.

Normal Labour

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