NORMAL_LABOUR and management of all stages

Normal labor

1. Ssali Shanitah

2. Definition of labour
Normal labour: defined as regular painful
uterine contractions which become
progressively stronger and more frequent
accompanied by the effacement and
progressive dilatation of the cervix and the
descent of the presenting part of the foetus.

3. Criteria for normal labour. Criteria for normal labour.
Spontaneous onset
Singleton pregnancy
Cephalic presentation.
37-42 weeks of gestation
No artificial interventions.
Unassisted spontaneous vaginal delivery.
Duration of <12 hours in nulliparous women, and <8
hours in multiparous women.
A labour which deviates from these features can be
described as abnormal.
A retrospective diagnosis.

5. Physiological onset of labour
•Hypothesis from animal experiments
•Endocrine
•Biochemical
•Mechanical stretch
•Fetoplacental contribution
•Activation of fetal Hypothalamo-pituitary-adrenal axis
•Not known fully
Distension and stretching e.g. by fetus or liquor amnii
Increased gap junctions, proteins, receptors for oxytocin
and specific contraction associated proteins

7. Estrogen
Increases release of oxytocin form maternal pituitary
Promotes synthesis of myometrial receptors for oxytocin, PGs and
increases myometrial gap junctions
Accelerates lysosomal disintegration in decidual and amnion cells
leading in increased PG2alpha synthesis
Stimulates synthesis of myometrial contractile protein through
cAMP (actinomyosin)
Increases excitabilty of myometrial cell membranes
Progesterone
Increased production of DHEA-S inhibits conversion of fetal
pregnenolone to progesterone. This reduced progesterone during
labour. Imbalance of estrogen progesterone ratio linked to PGs
synthesis

8. Prostaglandins
Initiate and maintain labour
Sites of production
Amnion
Chorion
Decidual cells
Myometrium
Synthesis triggered by
Increased estrogen levels
Glucocorticoids
Mechanical stretching
VEs
Amniotomy.
Vaginal infection
Cytokines (IL-1,6,TNF)

9. Basics of labour and delivery:
Stages of labour
Mechanics of labour
Cardinal movements of labour
Delivery

10. Stages of Labor
1
st
Stage (Interval between onset of labor and full cervical dilatation)
2 phases:
•Latent – period between onset of labour and up to cervical
dilatation of 3 cm (partograph) 4 cm (LCG).
•Active – begins from 4 cm (partograph) 5 cm (LCG) cervical
dilation up to full dilatation (10 cm).
2
nd
Stage (Interval between full cervical dilatation and delivery fetus)
Duration: Primigravida – 2 hours with out and 3 hrs with epidural
analgesia
Multiparous –1 hour without or 2 hrs with epidural analgesia
3
rd
Stage (Interval between delivery of the foetus and delivery of
the placenta and membranes)
Duration: maximum of 30 minutes

11. COMPONENTS OF LABOUR (4 P s)
The powers: Uterine contractions
The passages: bony pelvis, and soft tissues
The passenger: Foetus
Psyche
Mechanics of Labour

12. Mechanics of Labor
The Powers
–Forces generated by uterine musculature
–Frequency, amplitude, and duration of contractions
–Observation, manual palpation, tocodynamometry,
intrauterine pressure catheter (IUPC)
–Measured in Montevideo units
•Average strength of contractions (mmHG) x no. of
contractions in 10 minutes

13. Mechanics of Labor
Passenger
–Fetal size
•Abdominal palpation or Ultrasound
•Macrosomia is associated with failure to progress
–Lie
•Longitudinal axis of fetus relative to longitudinal axis of
uterus
•The lie can either be longitudinal, transverse or oblique
–Presentation
•Fetal part that directly overlies pelvic inlet
•Cephalic, breech, or shoulder?
•Compound – presence of >1 foetal part overlying the
pelvic inlet
•Malpresentation – any presentation that is not cephalic
with occiput leading.

14. Passenger (cont……)
- Attitude
Position of head with regard to fetal spine (ie:
degree of flexion or extension)
Flexion allows smallest diameter of fetal head
to present at pelvic inlet
- Position
Relationship of an arbitrarily chosen portion of
the fetal presenting part to the right or left side
of the birth canal
Mechanics of Labor

15. Mechanics of Labor
(A) vertex
(B) sinciput (C) brow
(D) face
Longitudinal lie. Ce
­phalic presentation. Differences in attitude of fetal
body,
Note changes in fetal attitude in relation to fetal vertex as the fetal head
becomes less flexed.

16. The relation of an arbitrary chosen point of the fetal
presenting part to the Rt or Lt side of the maternal birth
canal
The chosen point with its denominator
•Vertex presentation  occiput
•Face presentation  mentum
•Breech presentation Sacrum
Each presentation has two positions Rt or Lt
Each position has 3 varieties : Ant, transverse, post
POSITION
ROA
ROT
OA
LOA
LOT
LOP
ROP
OP

17. Mechanics of Labor

18. LONGITUDINAL LIE VERTEX PRESENTATION
LOPLOA

19. A. Right occiput posterior (ROP) Right occiput transverse (ROT)
Longitudinal lie. Vertex presentation

20. Rt mento-postRt mento-antLt mento-ant
Longitudinal lie. Face presentation. Left and right
anterior and posterior positions.

21. Longitudinal lie Breech presentation LSP

22. Anterior asynclitism
Naegele's obliquity
Normal synclitism Posterior asynclitism
Litzmann's obliquity Ear
presentation

23. Passenger (cont.)
–Station
•Measure of descent of presenting part
of the fetus through the birth canal.
–Multifetal Pregnancy
•Increase probability of abnormal lie and
malpresentation in labor
Mechanics of Labor

24. Passage
–Bony pelvis + soft tissues
–X-ray pelvimetry now rarely used, having been
replaced by a trial of labor
–4 types of the female bony pelvis
Mechanics of Labor

25. The mechanism of labour is explained by the change in the position
and the attitude of the fetus, as the fetus initiates its way through the
pelvis (birth canal).
Mechanism includes: 1) Engagement
2) Descent
3) Flexion
4) Internal rotation
5) Extension
6) Restitution/ External rotation
7) Expulsion
Mechanics of Labour
Cardinal Movements of Labor

26. Engagement
-Passage of widest diameter of presenting part to level
below the plane of the pelvic inlet
-0 station
-Occurs earlier in nulliparous women (36 wks)
The head engages in the transverse position.
Descent
Downward passage of presenting part through the pelvis.
Flexion
-Occurs passively as the head descends due to the shape
of the bony pelvis and resistance of pelvic floor soft
tissues
-Allows smallest diameter of fetal head to pass through
the pelvis.
Cardinal Movements of Labor

27. FLEXIONFLEXION
Lever action producing ftexion of the head; conversion from
occipitofrontal to suboccipitobregmatic diameter typically reduces the
anteroposterior diameter from nearly 12- to 9.5 cm.

28. FLEXIONFLEXION
Four degrees of head
flexion. Indicated by the
solid line the occipitomental
diameter; the broken line
connects the center of the
anterior fontanel with
posterior fontanel:
A. Poor flexion.
B. Moderate flexion .
C. Advanced flexion .
D. Complete flexion .
Note that with flexion com
­
plete the chin is on the
chest, and the
suboccipitobregmatic
diameter, the shortest
anteroposterior diameter of
the fetal head, is passing
through the pelvic inlet.

29. Internal Rotation
Rotation of presenting part from original position (transverse) to
anteroposterior position
Extension
Occurs once fetus has descended to the level of the introitus
Base of occiput in contact with inferior margin of symphysis pubis
External Rotation/restituition
Return of fetal head to correct anatomic position in relation to the fetal torso
Expulsion
Delivery of rest of fetus
Anterior shoulder delivered first with rotation under the symphysis pubis
Cardinal Movements of Labor

30. Cardinal Movements of Labor

31. Cardinal Movements of Labor

32. Mechanism of labor for the left occiput transverse position,
lateral view. Posterior asynclitism (A) at the pelvic brim followed
by lateral flexion, resulting in anterior asynclitism (B) after
engagement, further descent (C), rotation, and exten
­sion (D).

33. How to effectively deliver a baby
•Prepare for the delivery taking into account parity, progression of labor, presentation of
fetus, complications of labor
•When head crowns and delivery is eminent, protect the perineum + downward
pressure to keep head flexed
•Sterile towel used to palpate fetal chin through the rectum to apply upward
pressure to facilitate extension of fetal head
•After delivery of head
–Allow for external rotation (restitution).
–Reduce nuchal cord
–Suction fetal mouth and nares
•After clearing fetal airway
–Place a hand on each parietal eminence to apply downward traction to deliver anterior
shoulder
–Followed by upward traction to deliver posterior shoulder

34. •After complete delivery of infant
–Cradle in a single arm below the perineum to allow maximal blood
transfer to infant
•Delivery of the placenta
–3 classic signs of placental separation:
1- Lengthening of the umbilical cord
2- Gush of blood from vagina
3- Change in shape of the uterine fundus to a more globular
appearance
–Active management of 3
rd
stage.
–Brandt-Andrews Maneuver: abdominal hand secures the uterine fundus to
prevent uterine inversion while the other hand exerts sustained downward
“control cord traction” (control cord traction” (Do not PULL cord. Apply gentle traction)
–Crede maneuver – cord is fixed with lower hand while the uterine fundus is
secured and sustained upward traction is applied using abdominal hand
How to effectively deliver a baby

35.  Inspect the placenta
- Abnormalities of lobulation
- Site of insertion of umbilical cord into the placenta
Marginal insertion –inserts into edge of placenta
Membranous insertion – vessels course through the
membranes prior to attaching to placental disk
Length (50-60cm)
2 arteries and 1 vein
Single umbilical artery associated with 20% risk of
other structural anomalies.
How to effectively deliver a baby

36. Head crowns Head crowns

39. Reduce nuchal cord

40. DELIVERY OF ANTERIOR SHOULDER

41. Inspect the placenta

43.  REFERENCES.
William’s textbook of obstetrics
26TH edition.
Dutta’s text book of obstetrics 7
edition.