The presentation is on normal labour, stages and mechanisms, physiological basis of labour, abnormal labour, diagnosis and managment

1. The first stage of labour,
poor progression of labour,
and augmentation of labour
Dr Indunil Piyadigama

2. Labour
• Labour is a physiologic process during
which the products of conception (ie,
the fetus, membranes, umbilical cord,
and placenta) are expelled outside of
the uterus.
• Labour is achieved with gradual
effacement and dilatation of the
uterine cervix as a result of rhythmic
uterine contractions of sufficient
frequency, intensity, and duration

3. Mechanism of
labour

4. Pelvis (passage) • The true pelvis is shallow
anteriorly, formed by the
symphysis pubis (4–5 cm),
and deep posteriorly,
formed by the sacrum and
coccyx (10 cm). It is divided
into three parts – inlet,
cavity and outlet
• The pelvic inlet has a wide
transverse diameter –
approximately 13 cm, the
midcavity of the pelvis is
round, whilst the outlet
has a wide anterior
posterior diameter.

5. Uterine
activity
(power)
• The uterine contraction is characterized by
its intensity, frequency, and duration.
• Quantitative assessment of intrauterine
pressure to measure the strength of
uterine contraction is done by placement
of an intrauterine catheter.
• This is measured in Montevideo units
(MVU).
• Uterine activity varies in different stages
of labour:
• latent phase approximately 100 MVUs
• active phase of labour 175 MVUs
• 250 MVUs during the second stage

6. Fetus (passenger)
• For a successful outcome, the fetal skull, shoulders, trunk and buttocks should pass
through maternal pelvis.
• Several variables in the fetus influence its journey through the birth canal
• Fetal size
• Can be estimated by palpation, ultrasound scan and customized growth chart but all
of these methods are subjected to large degree of error.

7. • Long axis of the fetus to the mother – Longitudinal/
transverse/ oblique
• 99% longitudinal. Oblique is unstable
Lie
• Portion of the fetal body either foremost within the
birth canal or in close proximity to it
Presenting part
• Flexion or extension of the presenting part
• Depending on this from vertex/occiput to face
• Sinciput/ bregma – partially flexed
• Brow – Partially extended
Attitude (fetal posture)
• The relationship of the presenting part to the maternal
pelvis
Position

8. Stages of labour
• First stage of labour
• Begins with regular uterine contractions and ends with complete cervical
dilatation at 10 cm
• Divided into a latent phase and an active phase
• The latent phase begins with mild, irregular uterine contractions that soften
and shorten the cervix
• Contractions become progressively more rhythmic and stronger
• The active phase usually begins at about 3-4 cm of cervical dilation and is
characterized by rapid cervical dilation and descent of the presenting fetal
part
• For a nullipara the first stage of labor this lasts on average 8–18 hours
• In multiparous women it is between 5 and 12 hours

9. Second stage of labour
• Begins with complete cervical dilatation and ends with the delivery of
the fetus
• Birth is expected within 3 hours of the start of active second stage in
most nulliparous and within 2 hours in most multiparous women

10. Third stage of labour
• The period between the delivery of the fetus and the delivery of the
placenta and fetal membranes
• Delivery of the placenta often takes less than 10 minutes, but the
third stage may last as long as 30 minutes

11. Labour
mechanism
• The mechanism by which the largest diameter of the fetal
presenting part passes through the pelvic inlet.
• In occiput presentation this is the biparietal diameter.
• Normal sized head enters either transverse or oblique.
Engagement
• a continuous process throughout the first and second stage of
labour
Descent
• The flexion facilitates the shortest anterior–posterior diameter
suboccipito–bregmatic (9.5 cm) to be presented at the pelvic
outlet.
Flexion
• occiput gradually moves anteriorly towards the symphysis
pubis.
• This carries the long diameter of the head into the antero–
posterior diameter (A-P), i.e. the longest diameter of the pelvic
outlet from the previous occipito lateral positions.
Internal rotation

12. • The chin slides over the edge of the perineum
and becomes separated from the chest wall
• The vaginal outlet is stretched and crowning
occurs.
• With progressive distension of the perineum the
occiput, forehead, mouth and chin are delivered
successively
Extension
• The visible external movement of the fetal head
that corrects the torsion of neck sustained during
internal rotation.
• The direction of movement is opposite to that of
the internal rotation (45°). This allows the head to
come back in line with the shoulders. The occiput
points to the maternal thigh of the corresponding
side to which it originally lies.
Restitution

13. External rotation
• The movement of the head due to the internal
rotation of the shoulder as it comes in the antero–
posterior diameter of the pelvic outlet.
• This is visible externally in a direction opposite to
internal rotation.
• It occurs in the same direction as restitution.
• Now the shoulders are in antero–posterior diameter
(A-P) axis. The anterior shoulder escapes under the
pubic arch, while the posterior shoulder sweeps over
the perineum.
After the delivery of the shoulders, the rest
of body is delivered spontaneously by
lateral flexion

15. Physiology
• CRH
• CRH is both a hypothalamic and placental peptide.
• It is produced in varying concentrations throughout pregnancy and labour, but is known to increase
exponentially near term.
• CRH acts on targets within the fetal adrenal pituitary axis, placenta and myometrial smooth muscle, and is
thought to play a part in the initiation of labour.
• Prostaglandin
• Induce remodelling of the cervical extracellular matrix protein, and cell apoptosis by stimulating matrix
metalloproteinase (MMP) activity
• This leading eventually to fetal membrane rupture.
• Softening the cervix
• PGF2ɑ, PGHS-2 and PGE2 receptors augment myometrial responsiveness to contractile agonists
• PGF2ɑ, also contributes to placental separation
• Progesterone
• Inhibit myometrial contractility
• Suppresses oxytocin-induced prostaglandin production and the myometrial response to oxytocin
• Progesterone withdrawal is a key component in the facilitation of parturition.

16. • Oestrogen
• Rise in late pregnancy
• oestrogen enhances oxytocin receptor expression
• Oxytocin
• Oxytocin receptor concentration increases significantly as term approaches
• Binds to receptor and opens calcium activated channel
• Oxytocin has both direct and indirect actions.
• Acts directly on the myometrium to produce regular, effective contractions,
and
• Indirectly on the decidua to increase production of prostaglandins.

18. Diagnosis of
labour
2 features
•regular purposeful uterine
contractions
•cervical change
NICE advises to take
4cm as the active phase

19. Partogrm

20. Partogram
REDUCES OPERATIVE
DELIVERIES
REDUCES USE OF OXYTOCIN
IF LATENT PHASE INCLUDED
INCREASES CAESAREAN
SECTIONS
THERE ARE NO STUDIES ON
THE EFFECT OF HAVING OR
NOT HAVING AN ACTION LINE

21. Prolonged 1st stage of labour
Prolonged latent phase
• Nullipara > 20 hours
• Multipara > 14 hours
Primary dysfunctional labour/ protracted active phase
• Nullipara < 0.5cm/hour
• Multipara < 1cm/hour
Secondary arrest
• Secondary arrest of dilation is diagnosed when there has been no change in cervical
dilation for at least 2 hours

22. Prolonged
2nd stage
• If it exceeds 3 hours if regional
anaesthesia is administered
• 2 hours in the absence of
regional anaesthesia
In nulliparous women
• If it exceeds 2 hours with
regional anaesthesia
• 1 hour without it
In multiparous women

23. Causes of
prolonged
labour

24. Further
managment
• Assess uterine activity
• Can be infrequent (< 3-4 for 10 mins)
• Inadequate strength
• Short
• Incordinated
• Fetal size, presentation, position and attitude
• Pelvic assessment
• Look for signs of obstruction – Excessive caput/ moulding
• General well being of the mother
• Hydration
• Pain relief
• Position

25. Augmentation of labour
• Augmentation of labour is the process of stimulating the uterus to increase
the frequency, duration and intensity of contractions after the onset of
spontaneous labour
• Coordination of the contraction from fundus of the uterus towards the
cervix
• Can correct malpositions and malpresentations (flex head, rotate)
• Interventions may not be successful unless maternal wellbeing is improved

26. Amniotomy
• Amniotic sac is deliberately
ruptured so as to cause the release
of amniotic fluid
• Reduces duration of labour by 1hr
• Do not necessarily improve the
clinical outcomes
• No effect on analgesics or CS rate
• Discouraged because of 10%
chance of false labour

27. Oxytocin
• Oxytocin in delayed 1st stage reduce the time to delivery
• Does not alter the mode of delivery
• No change in neonatal outcome
• Different protocols used at different units. Using mU/min rather than
ml/min in these protocols are recommended
• Half life is 3 minutes
• Uterine overactivity can occur
• Water intoxication and hyponatremia
• If boluses given leads to hypotension

29. Prostaglandin
• Misoprostol 20 mic g have been observed to
have same effects as IV oxytocin
• No difference in side effects

30. Upright
posture
increases
spontaneous
delivery
Increased perineal
trauma and blood
loss is greater

31. Other
interventions
Oral/ IV hydration
Psycological support for the woman
correct diagnosis of labour
one to one midwifery care are
Walking – No effect
Food should be withheld – Gastric emptying is markedly
reduced and high risk of aspiration

32. Thank you