Normal Labor & Delivery

1. Normal Labor &
Delivery

2. Introduction..
Labor :
 regular uterine contractions of sufficient frequency, intensity, and duration that
lead to progressive cervical dilatation, effacement and descent of presenting part.
 3 Ps of labour: powers, the passages and the passenger.
 If any of the 3Ps are unfavourable, labour is likely to be abnormal resulting in the
need for intervention

3. Maternal Anatomy
• The pelvic inlet:
 Transverse diameter is 13.5 cm >
Anterior–posterior (A–P) diameter is
11.0 cm.
 The fetal head enters the pelvis
orientated in a transverse position in
keeping with the wider transverse
diameter.
 The angle of the inlet is normally 60°

4. Maternal Anatomy
• The Midpelvis
 It is almost round, as the transverse and A-P are
similar at 12cm.
 The ischial spines are palpable vaginally and are used
as important landmarks to:
1. To assess the descent of the presenting part on
vaginal examination (e.g. station 0 is at the level
of the ischial spines)
2. To provide a local anaesthetic pudendal nerve
block.

5. Maternal Anatomy
• The Pelvic Outlet
 The transverse is the widest diameter at
the inlet, but at the outlet it is the AP
diameter
 The fetal head must rotate from a
transverse to an AP position as it passes
through the pelvis

6. Pelvic Shapes

8. Fetal Anatomy
At the time of labour, the sutures
joining the bones of the vault are
soft, un-ossified membranes.
The sutures of the fetal face and
the skull base are firmly united.

9. Fetal Anatomy
Fetal skull moulding:
 Sutures are not fixed which allows the bones
to move together and even to overlap.
 The parietal bones usually slide over the
frontal and occipital bones
 Moulding reduces the diameters of the fetal
head and encourages progress through the
bony pelvis, while still protecting the
underlying brain

10. The diameters of the skull

11. Physiology of Labor
• The cervix: softens, shortens, thins out (effacement) and dilates for
labour to progress.
• The uterus: changes from a state of relaxation to an active state of regular
contractions to facilitate transit of the fetus through the birth canal.
• Each contraction must be followed by a resting phase in order to maintain
placental blood flow and adequate perfusion of the fetus.
• The pressure of the presenting part on the pelvic floor muscles produces
a maternal urge to push.

12. Physiology of Labor
 The uterus
• Uterine contractions happens in response to an increase in intracellular
calcium.
• Prostaglandins and oxytocin increase intracellular free calcium ions.
• Progressive shortening of the uterine smooth muscle cells is called
retraction and occurs in the cells of the upper part of the uterus
• Retraction results in the development of the thicker, actively contracting
‘upper segment’ and the lower segment of the uterus becomes thinner
and more stretched

13. • Contraction intervals of 2–4
minutes (i.e. 2 in 10 increasing to
4–5 in 10 in advanced labour)
• Their duration varies from 30 to 60
seconds or longer.
• The intensity or amplitude of the
intrauterine pressure during a
contraction averages between 30
and 60 mmHg. ( 200 MVU)

14. Physiology of Labor
 The cervix
• Under the influence of prostaglandins, there is an increase in proteolytic
activity and a reduction in collagen and elastin.
• Dermatan sulphate is replaced by the more hydrophilic hyaluronic acid,
which results in an increase in water content of the cervix.
• Causing cervical softening or ‘ripening’, so that when contractions begin
the processes of effacement and dilatation start.

15. Diagnosis of labor
The onset of labour can be defined as the presence of strong regular
painful contractions resulting in progressive cervical change
Loss of a ‘show’ or spontaneous rupture of the membranes (SROM) does
not define the onset of labour

16. Diagnosis of true labor pain
 History
• A history of regular painful uterine contraction in every 5- 8
min, accompanied by the history of a bloody show or
spontaneous rupture of membrane
 Physical examination
• Reduction of interval between uterine contractions
• Abdominal pain of increasing intensity
• Cervical effacement (≥ 50%)
• Cervical dilation (≥ 2 cm)

18. Normal labor
Spontaneous onset
Single 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.

19. Stages Of Labor
 There are three stages of labor:
• The first stage (stage of dilatation of the cervix) is from the onset of true labor
(regular uterine contractions) to complete dilatation of the cervix
• The second stage (stage of fetal delivery ) is from complete dilatation of the
cervix to the birth of the baby
• The third stage (stage of placental delivery) is from the birth of the baby to
delivery of the placenta.

20. Stages Of Labor
First stage
• It is the stage of cervical dilatation.
• Starts with the onset of true labor pain and ends with full dilatation of
the cervix i.e. 10 cm in diameter.
• It takes about 10-14 hours in primigravida and about 6-8 hours in
multipara

21. Phases of cervical dilatation
Latent phase:
• This is the first 3 cm of cervical dilatation which is slow takes about 8 hours
in nullipara and 4 hours in multipara.
Active phase:
• The time between the end of the latent phase (3–4 cm dilatation) and full
cervical dilatation (10 cm)
• Lasting between 2 and 6 hours, shorter in multiparous women
• Cervical dilatation during the active phase occurs typically at 1 cm/hour
or more
• It is considered abnormal if it occurs at less than 1 cm in 2 hours.

22. Stages Of Labor
Second stage
• It is the stage of expulsion of the fetus.
• Begins with full cervical dilatation and ends with the delivery of the
fetus.
• Its duration is about 50 minutes in primigravida and 20minutes in
multipara
• considered prolonged if more than one hour in multiparas and more than
2 hours in primigravidea

23. Phases Of Second stage of Labor
 The ‘passive phase’
• The time between full dilatation and the onset of involuntary expulsive
contractions
• There is no maternal urge to push and the fetal head is still relatively high in the
pelvis.
 The second phase ‘active second stage’.
• There is a maternal urge to push because the fetal head is low (often visible),
causing a reflex need to ‘bear down’
• normal active second stage should last no longer than 2 hours in a nulliparous
woman and 1 hour in multipara

24. Stages Of Labor
 Third stage
• It is the stage of expulsion of the placenta and membranes.
• Begins after delivery of the fetus and ends with expulsion of the placenta
and membranes.
• Its duration is about 10-20 minutes in both primi and multipara. normally
not exceed 30 minutes with active management of third stage

25. Duration of Labor
 Prolonged Labour
• labour lasting longer than 12 hours in nulliparous women and 8 hours in
multiparous women.
 Precipitous labour
• defined as expulsion of the fetus within less than 3 hours of the onset of
regular contractions.

26. Mechanisms of labor
 Fetal lie :
The relation of the fetal long axis to that of the mother
• Longitudinal
• Transverse
• Oblique
• A longitudinal lie is present in more than 99% of labors at term.
• Predisposing factors for transverse fetal position include
multiparity, placenta previa, hydramnios

27. Mechanisms of labor
 Fetal presentation :
• The portion of the fetal body that is either foremost within the birth
canal or in the closest proximity to it.
• Cephalic 96.8%
• breech 2.7 %
• Shoulder 0.3%
• Compound 0.1%

28. Mechanisms of labor
 Cephalic presentation
• Well flexed head (vertex or occiput presentation)
• Sinciput presentation (Military ) === transient
• Brow presentation 0.01 % === transient
• Face presentation 0.05%
• As labor progresses, sinciput and brow presentations almost always convert into
vertex or face presentations by neck flexion or extension, respectively.

29.  Fetal Attitude:
 Position of head with regard to
fetal spine (ie: degree of flexion or
extension)
• A - suboccipitobragmatic (vertex)
• B - occipitofrontal (military)
• C - mentovertical (brow )
• D - submintobragmatic (face)
** OP with occipitofrontal 11.5
Or suboccipitofrontal 10

31. Breech presentation
 Incidence:
• 25 % 28 weeks GA
• 17% 30 weeks GA
• 11% 32 weeks GA
• 2.7 % term

33. Presenting parts diameter in cephalic
presentation

34. Mechanisms of labor
Fetal position
• Relation ship of chosen portion of the fetal presenting part to the right or
left side of the birth canal (ROA, LOA , ROP, RMA…..)
• DOMINATOPRS:
 Vertex
 Face
 Breech
 Shoulder
• Occiput
• Mentum
• Sacrum
• Acromiun

39. Diagnosis Of Fetal Presentation & Position
• Abdominal palpation
• Vaginal examination:
- Presenting part
- Position
- Dilatation
- Effacement
- Station
- Pelvimetry
• Auscultation : arounf the umbilicus in longitdunal lie , below if cephalic and above if breech

41. Vaginal Examination
Head station :
Relationship of presenting
part to the ischial spine

42. Bishop score

43. The Mechanism Of Labor (OA)
 Cardinal movements of labor
1. Engagement
2. Descent
3. Flexion
4. Internal Rotation
5. Extension
6. Restitution And External Rotation
7. Expulsion

44. The Mechanism Of Labor
 Engagement
• Passage of widest diameter of
presenting(in transverse position) part
to level below the plane of the pelvic
inlet
• Occurs earlier in nulliparous women
(36 wks)

45. The Mechanism Of Labor
 Descent
• Descent of the fetal head is needed before
flexion, internal rotation and extension can
occur
 Flexion
• Occurs passively As the
• head descends into the narrower midpelvis

46. The Mechanism Of Labor
 Internal Rotation
 Rotation of presenting part from original position (transverse) to
anteroposterior position
 If the head is well flexed, the occiput will be the leading point

47. The Mechanism Of Labor
 Extension
The well-flexed head now extends
and the occiput escapes from
underneath the symphysis pubis and
distends the vulva.
This is known as ‘crowning’ of the
head.

48.  Restitution
This slight rotation of the occiput
through one eighth
of the circle
The Mechanism Of Labor
 External rotation
The shoulders have to rotate into the direct AP
plane, Then the occiput rotates through a
further one-eighth of a circle to the transverse
position.

49. The Mechanism Of Labor
 Expulsion
The anterior shoulder is under the
symphysis pubis and delivers first, and
the posterior shoulder delivers
subsequently.

50. In occipito-posterior
Mechanism of labour is identical to OT &
anterior varieties
The occiput rotate to the symphysis pubis
through 135º instead of 90º or 45º
If rotation does not occur direct occiput
post or
Partial rotation transverse arrest

51. Management In First Stage
 Vaginal examinations are usually performed every 4 hours to determine
when the active phase has been reached
 Laboring woman should be allowed to assume the position she finds most
comfortable— this will be lateral recumbency most of the time
 Sips of clear liquids, occasional ice chips are permitted

52. Management In Second Stage
 The first sign of the second stage is likely to be an urge to push.
 In all cases the baby should be delivered within 4 hours of reaching full
dilatation
 Once the head has crowned, the perineum should be supported the
woman should be discouraged from bearing down by telling her to take
rapid, shallow breaths
 To aid delivery of the shoulders, there should be gentle traction on the
head downwards and forwards until the anterior shoulder appears
beneath the pubis

54. Fetal Care
Fetal monitoring:
• Low risk : every 30 min in first stage and 15 min in second stage
• High risk : every 15 min in first stage and every 5 min in the second stage
or continuous

55. Episiotomy
It is a second degree pereneal tear man made by scissors
Types: Midline, medio-lateral and lateral, Mediolateral is commonly used.
Indication: complicated vaginal delivery (breech, shoulder dystocia, forceps,
vacuum), scarring from female genital cutting or poorly healed third or fourth
degree tears and fetal distress.

56. Episiotomy
Wait to perform episiotomy until: the perineum is thinned out; and 3-4 cm of
the baby's head is visible during a contraction
Complications: Hematoma, infection and rarly necrotizing fasciitis
Episiotomy should be restricted to an indication

58. Management In Third Stage

59. Management In Third Stage
 Management of the third stage can be ‘active’ or ‘physiological’.
 Physiological management
• Is where the placenta is delivered by maternal effort and no uterotonic drugs are
given to assist this process
 Active management
• When the signs of placental separation are recognized, controlled cord traction is
used to expedite delivery of the placenta.

60. Management In Third Stage

61. Oxytocin dose is 10 IU, intramuscularly. with intravenous access in place, 10-20 IU is
placed in 500-1000 mL of crystalloid and run quickly. With cesarean deliveries, 5 IU is
administered as an intravenous bolus, followed by a similar infusion.
Ergometrine dose: is 0.2-0.25 mg, some used 0.5 mg ; IM or IV.
Syntometrine (contains 0.5 mg of ergometrine with 5 IU of oxytocin);
Oxytocin and ergometrine acts within 30 seonds if given IV and oxytocin acts after 3
mints while ergometrine after 6-8 mints if given IM
Management In Third Stage

62. Advantages of Active Management
 Advantage:
• reduction of the blood loss (60% reduction of blood loss )
 Disadvantages:
• Constriction ring may occur with retention of the placenta.
• Avulsion of the cord if undue pressure is applied.
• Inversion of the uterus if fundus is pressed while the uterus is lax.

63. Placental Examination
Examination of the placenta & membranes:
• by exploring it on a plain surface to be sure that it is complete. If there is missed
part, exploration of the uterus is done under general anaesthesia.