1. Normal Labor and Delivery
Dr Narine Singh MBBS ,MSc

2. Normal Labor
In order to maximize the patient chance of a
vaginal delivery ,it is important to understand
the basics of labor
• Stages of labor
• Mechanics of labor
• Cardinal movements of labor
• delivery

3. Normal Labor and Delivery
• Definition of labor
• Factors influencing progress of labor
• Diagnosis of labor
• Stages of labor
• Mechanism of labor
• Management of labor

4. What is Labor
Definition
Labor is a physiologic process during which the
products of conception (i.e. fetus ,membranes
,umbilical cord and placenta) are expelled from the
uterus
More specifically, Labor requires the onset of
regular ,effective contractions that lead to
progressive cervical effacement and dilatation of
the cervix accompanied by descent of the
presenting part

5. Definition
Labour is
regular ,frequent uterine contraction
+
cervical change
(dilatation and effacement)

6. Labor can occur at
• Preterm labor --- prior to 37 weeks
• Term --- 37-42 weeks
• Post term --- after 42 weeks
• Postdates --- after 40 weeks

7. Normal Labour
Labour is normal when it is
• Spontaneous in onset
• At term (37 completed weeks-42 weeks)
• Single fetus
• Vertex presentation
• Within a reasonable time(not less than 3 hrs
or more than 18 hrs.)
• Without complication to the mother or the
fetus

8. Normal Labour
• Any deviation from this definition is abnormal
• In late pregnant ,strong contraction can sometimes be
palpated that do not produce cervical dilatation ,even
when the cervix is normal and these do not constitute
true labour (Braxton – Hick)
• Cervical dilatation in the absence of uterine contraction
suggest cervical insuffiiciency,whereas uterine
contraction without cervical change does not meet the
definition of labour
• Delivery refers to the complete expulsion of the
products of conception

9. Normal labor
Braxton –Hick uterine contraction NOT
associated with cervical change
• Shorter in duration
• Less intense
• Over lower abdomen and groin
• Resolves with ambulation

10. Onset of labour
• Based on the naegel’s formula ,labour starts
approximately as follow
• In the expected date of delivery (EDD) in
40%of cases
• One week on either side in 50% of cases
• Two weeks earlier and one week later in
80%of cases
• At 42 weeks in 10%of cases
• At 43 weeks plus in 4% of cases

11. Causes of onset of labour
The actual cause for the onset of labor is not
exactly known ,but several theories have been
postulated but none of them is completely
proven
• Hormonal factors
• Mechanical factors

12. Onset of labour
Hormonal factors Mechanical factors
• Estrogen theory • Uterine distension theory
• Progesterone withdrawal
theory
• Prostaglandin theory
• Oxytocin theory
• Fetal cort

13. Hormonal factors
• Estrogen theory
• Progesterone withdrawal theory
• Prostaglandin theory
• Oxytocin theory
• Fetal cortisol theory

20. Stages of labour
Obstetricians have divided labour into 3 stages
that delineate milestones in a continuous
process

21. Stages and Phases of labor
• The first stage begins with the onset of labor
and ends with full cervical dilation .Friedman
subdivided the first stage into latent and
active phases

23. • The Latent phase begins with regular uterine
contractions and ends when there is an increase
in the rate of cervical dilation
• . It is complete when a nulliparous woman
reaches 3– 4 cm dilatation and a parous woman
reaches 4– 5 cm . Cervical length should usually
be <1 cm . The onset of the latent phase is often
difficult to define. According to Friedman the
onset of the latent phase is define as the point at
which the mother perceives regular contraction

24. • The active phase is characterized by an
increase in rate of cervical dilation and
descent of the presenting fetal part .It ends
with complete cervical dilation ,and is further
subdivided into :
• Acceleration Phase A gradual increase in the
rate of dilation initiates the active phase and
marks a change in rapid dilation
• Phase of maximum slope, The period of
active labor with the greatest rate of cervical
dilation

25. • Deceleration Phase . During the terminal
portion of the active phase ,the rate of
dilation may slow until full cervical dilation
• .Cervical dilatation rate of 1.2 cm /hr. for
nulliparous and 1.5 cm/hr for parous women

29. First stage of labor
Duration
• Primigravida – 8 -12 hours
• Multigravida -6-8 hours
Latent phase
• In primigravida – 8 hours
• In multigravida – 4 hours
Active phase
• In primigravida – 4 hours
• In multigravida – 2 hours

36. Stages and Phases of labor
• The second stage of labor is the interval
between full cervical dilation and delivery of
the neonate

37. Second stage of labour
The second stage has 2 phases
• Passive: Cervix is fully dilated ,fetal descent continued
during the time from full dilatation until an urge to
push is felt at about station+ 2 station
• Active :Time from the onset of the urge to push until
delivery Presenting part of fetus reaches the pelvic
floor. The fetal head will become visible at the introitus
,initially appearing and disappearing between
contractions. Once the head is crown ,it does not
recede in between contraction .The fetus moves
through the birth canal and is completely delivered

39. Third stage of labour
• The third stage is the interval between
delivery of the infant and delivery of the
placenta and membranes
• Its duration is 10-20 minutes in both primi and
multipara
• The third stage is considered prolonged after
30 minutes, and active intervention ,such as
manual extraction of the placenta is
commonly considered