Normal Labor

Kingdom of Saudi Arabia

Ministry of Higher Education

King Faisal University

College of Medicine

By/ Fahad AlHulaibi Mansour Al Omair Ahmed Al Awwad Abdulaziz Al Barrak

Objectives

By end of this Tutorial, you will be able to :

Diagnose The Onset Of Labor .

Define Stages Of Labor.

Understand The Mechanism Of

Normal Labor.

Monitoring The Mother & The Fetus During

Labor.

Understand Management Of Normal

Labor.

30 months

-

24 months

=

6 months

Or

24 weeks “age of viability”

Definition

Labor:

Is the process whereby the product of conception are

expelled from uterian cavity after 24th week of

gestation.

Definition

Premature labour:

labour occurring before the commencement of the 37th

week of gestation

Prolonged labour:

labour lasting in excess of:

24 hours in a primigravida

&16 hours in a multigravida.

Onset of labour

The onset of labour is defined as the time of onset of regular, painful uterine contractions, which produce progressive effacement and dilatation of the cervix.

false labour: where the onset of painful contractions is not associated with progressive dilatation of the cervix.

The clinical signs of the onset of labour include:

1. The onset of regular, painful contractions that

produce progressive cervical dilatation.

2. The exhibition of a vaginal show - the passage of

blood stained mucus.

3. Rupture of the fetal membranes - may occur at the

time of onset of contractions or it may be delayed

until the delivery of the fetus.

Stages of labour

The First Stage

• onset of labour start

• Cervix reached full dilatation end

The Second Stage

• Cervix reached full

dilatation start

• expulsion of the fetus end

The Third Stage “Placenta Stage “

• delivery of the child. start

• expulsion of placenta. end

The classic signs of placental separation :

1. show of bright blood.

2. apparent lengthening of the umbilical cord

3. elevation of the uterine fundus within the abdominal

cavity .

MECHANISM OF

NORMAL LABOUR

Mechanism of Normal labour

Engagement of the head normally occurs before the

onset of labour in the primigravid woman but may not

occur until labour is well established in a multipara.

Only 2/5th of the head will be palpable per

abdomen

Zero station on vaginal examination

Mechanism of labour

1. Descent of the head provides a measure of the

progress of labour

Descent occurs throughout

labour

2. Flexion of the head occurs as it descends and meets the pelvic floor, bringing the chin into contact with the fetal thorax.

Flexion produces

a smaller diameter

of presentation

(suboccipitobregmatic

diameter)

3. Internal rotation:

The head rotates as it reaches pelvic floor and the

occiput normally rotates anteriorly from the lateral

position towards the

pubic symphysis

4. Extension: The acutely flexed head descends to

distend the pelvic floor and the vulva, and the base

of the occiput comes into contact with the inferior

rami of the pubis.

The head now extends until

it is delivered. Maximal

distension of the perineum

and introitus accompanies

the final expulsion of the

head, a process that is

known as crowning.

5. Restitution:

Following delivery of the head, it rotates back to be

in line with its normal relationship to the fetal

shoulders

6. External rotation: When the

shoulders reach the pelvic floor,

they rotate into the

anteroposterior diameter of the

pelvis. This is accompanied by

rotation of the fetal head so that

the face looks laterally at the

maternal thigh.

7. Delivery of the shoulders: The anterior shoulder

is delivered first by traction posteriorly on the fetal

head so that the shoulder emerges under the pubic

arch.

The posterior shoulder is

delivered by lifting the head

anteriorly over the perineum.

This is followed by rapid

delivery of the remainder of

the trunk and the lower limbs

INTRAPARTUM

MONITORING

What to monitor?

Mother

Temperature

Pulse rate

Blood pressure

Urine

Fetus

Auscultation

Fetal CTG

Fetal ECG

Scalp stimulation test

Acid-Base balance

Others

Partogram

Mother Intrapartum monitoring

Temperature

Normal Temperature

36.2°-37.2°

Frequency

Every 4 hours

Pyrexia; Causes

Infection

Maternal exhaustion: Dehydration cause pyrexia.

Risks

Mother

fetus

Cont.

Pulse Rate

Normal Range

70-100 beats per min

Frequency

Hourly

Blood Pressure

Normal Range

100/60 mm Hg to 140/90 mm Hg

Frequency

hourly

Urine

Items

Volume

Protein

Ketones

Frequency

Every 2 hours

Fetal Monitoring

Auscultation

Fetal CTG

Fetal ECG

Acid-Base balance

Scalp stimulation test

Others

Vibroacoustic stimulation

Fetal oxygen saturation

Auscultation

The heart rate should be recorded every 15 minutes

in the first stage and after each contraction in the

second stage, using a Pinard fetal stethoscope

Cardiotocography is not required when the labour

is classified as low risk.

However, there are specific indications for electronic

fetal monitoring.

Indications for continuous electronic

fetal monitoring

Maternal

Previous caesarian section

Pre-eclampsia

Post-term pregnancy

Prolonged rupture of the membranes

Induced labour

Diabetes

Antepartum haemorrhage Other maternal medical

diseases

Cont.

Fetal

Fetal growth restriction

Prematurity

Oligohydramnios

Multiple pregnancy

Meconium-stained liquor

Breech presentation

Cardiotocogram

Components:

Base line fetal heart rate

Base line variability

Accelerations

Decelerations

Uterine Contractions

Fetal Heart Rate

Normal Range

110-160 beats/min

More than 160 is tachycardia

Less than 110 is bradycardia

Baseline Variability

Normal Range

6-25

Increased (more than 25)

Early Hypoxia

Prolonged pregnancy

Decreased (less than 6)

Late hypoxia

Sleep

Vibro-acoustic stimulation

Accelerations

Transient increase in heart rate more than or equal

to 15 beats for more 15 seconds.

Assuring of good fetal health if present

Decelerations

Transient decrease in heart rate more than or equal

to 15 beats for more 15 seconds.

Normally not present.

Types (in relation to uterine contractions)

Early

Late

Variable

Early Decelerations

They are synchronous with uterine contractions.

The nadir of the deceleration occurs at the peak of

the contraction and the decrease in heart rate is

generally less than 40 beats/min.

Cont.

These decelerations are generally due to head

compression and are commonly considered to be

physiological.

They are a common form of deceleration seen in

labour

Late Decelerations

The onset of the slowing of heart rate occurs well

after the contraction is established and does not

return to the normal baseline until at least 20

seconds after the contraction is completed.

They are indicative of fetal hypoxia.

Variable Decelerations

Variable decelerations vary in timing and

amplitude, hence their name.

An early deceleration where the heart rate falls by

more than 40 beats/min is also classified as a

variable deceleration.

Types:

Mild: Total duration is >30 sec, or FHR >80 bpm

Moderate: FHR 80-70 bpm

Severe: FHR <70 bpm for more than 1 min

Cont.

The commonest cause is cord compression and the

changes may be considered to be pathological if

the cord compression is persistent

Uterine Contractions

Tocodynamometer

A pressure-sensitive tocodynamometer is placed around

the maternal abdomen.

The tocodynamometer measures only the frequency of

contractions, not their intensity or strength.

Intrauterine pressure catheter (IUPC).

This method allows internal monitoring of contractions.

IUPC measures both the frequency and strength of

contractions.

Electrocardiogram

The fetal electrocardiogram (ECG) can be recorded

from scalp electrodes or by the placement of

maternal abdominal electrodes.

Two items are important:

Acidosis (T wave and QRS height)

Asphyxia (PR interval and RR interval)

The fetal ECG can also be used to identify the

nature of fetal arrhythmias.

Scalp stimulation test

The examiner rubs the fetal scalp during a digital

examination.

An acceleration is usually seen in the FHR tracing of the

uncompromised, nonacidotic fetus. The presence of an

acceleration is associated with an intact ANS and a

fetal scalp blood pH greater than 7.20.

If an acceleration is not obtained after scalp

stimulation, fetal scalp blood can be sampled to

measure the fetal pH or one can progress to immediate

surgical delivery.

Fetal scalp blood sampling

The fetal scalp is visualized through the dilated cervix, and blood is collected in heparinized capillary tubes

The normal fetal capillary pH is 7.25 to 7.35 in the first stage of labor.

A fetal scalp pH greater than or equal to 7.20 is reassurance that the fetus is not acidotic. Labor can proceed for 20 to 30 minutes.

A pH of less than 7.20 may represent significant acidosis. Delivery is thus indicated by vaginal delivery, if possible, or cesarean delivery.

Others

Vibroacoustic stimuli (VAS). Fetus is stimulated by noise

for 1 second.

The presence of fetal accelerations in response to VAS is

considered reassuring.

The fetus is restimulated if no accelerations occur within 10

seconds. The VAS test may be repeated up to four times.

Normal fetal oxygen saturation: ranges between 35%

and 75%, If the fetal oxygen saturation remains above

30% during labor, fetal metabolic acidosis is excluded.

Partogram

Partogram is a graphical record of key data

(maternal and fetal) during labour entered against

time on a single sheet of paper.

Components

Fetal Parameters:

FHR

Status of membranes or Amniotic Fluid

Moulding

Caput

Progress of Labor:

Cervical dilatation

Station of head

Uterine contractions: Frequency & Duration

Oxytocin:

Concentration / L

Infusion rate

Any other medicine & IV fluid

Maternal Parameters:

Vital data:

Pulse

BP

Temparature

Urine:

Output

Acetone

Protein / Glucose

MANAGEMENT OF

NORMAL LABOUR

General principles of the management of

the first stage of labour :

• Observation and intervention if the labour becomes

abnormal by partogram .

• Pain relief during labour and emotional support for

the mother ( Narcotic agents , inhalational analgesia

and regional analgesia )

• Adequate hydration throughout labour.

Fetal monitoring in labour

• Fetal cardiotocography

• Basal heart rate

• Transitory changes

• The fetal electrocardiogram

• Fetal acid-base changes

• Scalp blood sampling

Management of the second stage

Delivery of the head .

Controlled descent .

Minimizing perineal damage.

Clamping the cord .

Evaluation of Apgar score.

Evaluation of the Apgar score

2 1 0

Pink Blue White Colour

Normal Rigid Flaccid Tone

>100 <100

beats/min

Impalpable Pulse

beats/min

Regular Irregular Absent Respiration

Normal Poor Absent Response

Management of the third stage

Recognition of placental separation.

Assisted delivery of the placenta with cord traction.

Routine use of oxytocic agents with crowning of the head.

References:

Essential Obstetrics and Gynaecology, 4th Ed

Thank

you