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Normal Labor and
Delivery
Midwifery Division
Department of OB/GYN
University of North Carolina
School of Medicine
OBJECTIVES
• Define labor and its stages
• Exam of the laboring woman and her fetus
• Review the cardinal movements of labor
and birth
• Review Disorders of Labor
• Induction of Labor
• Other labor issues
Define Labor and its Stages
• Labor: progressive change of the cervix in
the setting of uterine contractions
• Term Labor: > 37 weeks gestation
• Preterm Labor: < 37 weeks gestation
– 11% of all US births in 1997
– 80% of preterm births between 34 - 36
weeks
– Preterm delivery < 35 weeks: 3.5%
Define Labor and its Stages
• Stages of Labor
• 1st stage – onset of labor until full cervical
dilitation
• 2nd stage – from full dilitation to birth of
infant
• 3rd stage – from birth of infant until delivery
of placenta
• 4th stage – 2 hours after the delivery of
placenta
Define labor and its Stages
1st stage and its phases
• Latent phase: onset of contractions
until active phase
• Active phase: 3 cm dilation in
nulliparas; 4 cm dilation in
multiparas to deceleration phase
• Deceleration phase: 8 – 9 cm dilation
to complete dilation
Exam of the Laboring woman
and her Fetus
• Review of prenatal records and labs
• Physical exam
– 1. Vitals and routine physical exam
– 2. Abdominal Exam
• Palpation of contractions
• Leopold’s maneuvers
– 3. Pelvic Exam
– 4. Fetal heart rate monitoring
Review of Prenatal Records
• Allergies
• Medications
• Past medical, surgical, obstetrical,
gynecologic, social and family histories
• Routine prenatal lab work
• Complications of current or past
pregnancies
Abdominal Exam
– 1. Palpation of contractions for duration and
intensity
– 2. Leopold’s maneuvers
• To assess estimated fetal weight, fetal lie,
presentation and position, attitude, and
(a)synclitism
NORMAL LABOR & DELIVERY
Estimated Fetal Weight
• Leopold’s maneuvers (palpation of
the maternal abdomen)
• Ultrasound estimate of fetal weight
(error of 10 – 15%)
• Maternal estimate of fetal weight
(best)
Fetal Lie
• Lie: relationship between the long
axis of the fetus and the mother
Longitudinal
– Transverse
– Oblique
–
Fetal presentation
• Presentation: fetal part closet to pelvic inlet
– cephalic
– breech
– shoulder
Fetal position
• Position: relationship of fetal presenting part to
the maternal pelvis
–
–
–
–
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Occiput
Brow
Mentum
Breech
Shoulder
Fetal Attitude
• The relationship of the fetal parts to one
another (i.e. flexion  extension of head
relative to body).
Vertex
Parietal
Brow
Face
(A)synclitism
• Synclitism is when the biparietal diameter
of the fetal head is parallel to the planes of
the maternal pelvis.
Pelvic Exam
• Pelvic Exam – sterile vaginal exam +/sterile speculum exam
• Dilation
• Effacement
• Station
• Also position of cervix and consistency
important.
Obstetrical Pelvic Exam
• Dilation (dilatation): patency of the internal
cervical os
– 0 = “closed”
– 10 cm = “complete”
• Effacement: shortening of the cervical
length
– 0% = “thick”
– 100% = “fully effaced”
Obstetrical Pelvic Exam
• Station: level of presenting part
(bony portion) in relation to the
maternal ischial spines
– Ischial spines = O station
– Above spines: -5 to -1
– Below spines: +1 to +5
Obstetrical Pelvic Exam
• Also includes same assessment included in
Leopold’s maneuvers (fetal lie, presentation,
position, etc.)
Fetal Monitoring
• Intermittent
• Continuous
Continuous Fetal Monitoring
• Baseline rate
• Variability
• Presence of accelerations
• Presence of decelerations
• Changes or trends of FHR patterns
over time
• Contractions
Fetal Heart Rate Baseline
• 10 minute window
• Duration: at least 2 minutes
• Bradycardia: < 110 bpm
• Tachycardia: > 170 bpm
Fetal Monitoring (Variability)
• Concept of short and long-term
variability dropped
• Absent: undetectable
• Minimal: undetectable - < 5 bpm
• Moderate: 6 - 25 bpm
• Marked: > 25 bpm
Fetal Monitoring
(Accelerations)
• Onset to peak: < 30 seconds
• > 32 weeks: >15 bpm X >15 secs
• < 32 weeks: > 10 bpm X > 10 secs
• > 2 minutes in duration: prolonged
• > 10 minutes in duration: change in
baseline
DECELERATIONS
Fetal Monitoring (Variables)
• Onset to nadir < 30 secs
• > 15 bpm below baseline
• Duration: > 15 seconds
• < 2 minutes from onset to return
to baseline
DECELERATIONS
Fetal Monitoring (Variables)
Treatment
• Pelvic exam (rule out prolapsed cord)
• Maternal oxygen
• Change maternal position
• Stop pushing
• Amnioinfusion
Fetal Monitoring
(Early Decelerations)
• Onset to nadir > 30 secs
• Coincident in timing with UC
• Nadir occurring simultaneously
with the peak of the contraction
Fetal Monitoring
(Late Decelerations)
• Onset to nadir > 30 secs
• Delayed in timing
• Nadir occurring after the peak of
the contraction
• Reccuring can be ominous
Fetal Monitoring
(Late Decelerations)
Treatment
• Correct hypotension or other maternal
conditions
• Maternal oxygen
• Scalp stimulation
• Cesarean delivery if repetitive
Uterine Contractions
• External tocodynamometry
• Internal tocodynamometry
What’s going on in there?
• The cardinal movements of labor are the
mechanism by which the fetus moves
progressively through the birth canal.
Cardinal Movements of Labor –
Occurring during first and
second stages of labor
1. Engagement: descent of biparietal diameter
to the level of the ischial spines (0 station)
–
Often occurs before onset of labor in nulliparous
patients
2. Descent
3. Flexion: presenting diameters of fetal head
presenting to maternal pelvis are optimized
Cardinal Movements of Labor
4. Internal rotation: fetal occiput rotates
from transverse to AP
5. Extension: head rotates under
symphysis pubis
6. External rotation (restitution): occiput
and spine assume same position
7. Expulsion: fetal body delivers
3rd and 4th stages
• Delivery of placenta
• Bonding, etc
So what if it doesn’t happen like
that?
• Disorders of the 4 stages of labor
Abnormalities of Labor
THE 5 “P”
• Passageway: maternal pelvis
• Powers: uterine contractions
• Passenger: fetus
• Placenta: perfusion
• Psyche: mother’s readiness
1st stage disorders
Slow rate of dilation in the active
phase of labor
– < 1.2 cm/hr in nulliparas
– < 1.5 cm/hr in multiparas
• Abnormal latent phase
• Abnormal Active phase
Abnormal Latent Phase of
Labor
• > 20 hours in nulliparas
• > 14 hours in multiparas
• Treatment
– Therapeutic rest
• Morphine (10- 20 mg)
• Hypnotic (Ambien)
– 85% proceed into active phase of labor
– 10% - no contractions
– 5% - may need oxytocin
Disorders of the Active Phase
• Secondary Arrest: cessation of
previously normal rate of dilation for
two hours
• Combined Disorder: cessation of
dilation when patient has previously
exhibited a primary dysfunctional labor
2nd stage disorders
Disorders of the Second Stage
• Protracted Descent:
– < 1 cm/hr in nulliparas
– < 2 cm/hr in multiparas
• Prolonged:
– Nulliparas
• With epidural – 3 hours
• No epidural – 2 hours
– Multiparas
• With epidural – 2 hours
•
No epidural – 1 hour
Episiotomy
Need for this now signifies an
abnormality of second stage
• Originally thought to protect perineum
• Now thought to result in more 3rd and
4th degree extensions
• More perineal pain
• At UNC less that 3% of patients
Forceps Assisted Vaginal
Delivery
• Outlet forceps:
– Scalp visible at the introitus w/o parting the labia
– Sagittal suture < 45 degrees
• Low forceps:
– Leading point of skull at +2 or below
• < 45 degrees
• > 45 degrees
• Mid-forceps:
– Head is engaged but presenting part is above +2 station
– Rarely done
NORMAL LABOR & DELIVERY
Vacuum vs Forceps
• Forceps
– More maternal trauma
– Minimal fetal trauma (bruising)
• Vacuum
– Less maternal trauma
– Potential for increased fetal trauma
(subgaleal bleeding)
Mitivac vacuum
Ritgen Maneuver
Erb’s palsey
3rd stage disorders
Retained placenta
• Adherent
• Accreta, etc
POST PARTUM HEMORRHAGE
Causes:
– Atony of the uterus
– Placenta problem
– Laceration
Defined as greater than 500 ml for vaginal birth
Average EBL with C/S = 1000ml.
TREATMENT FOR PPH
• Find the cause and treat promptly
• Active management of the third stage
• Med: Pitocin
Cytotec
Methergine
Hemabate
And now you want to do what?
• Laceration repair
NORMAL LABOR & DELIVERY
Lacerations
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Cervical (use clock to describe location)
Vaginal (left or right)
Periurethral
Clitoral
Perineal
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1st degree: skin only involved
2nd degree: skin and subcutaneous tissue
3rd degree: external rectal sphincter
4th degree: rectal mucosa not intact
First degree
External sphincter
Second degree
External sphincter
Third degree
Disorders of 4th stage
• Bonding
• Delayed postpartum hemorrhage
Induction of Labor – Why mess
with a good thing?
• Maternal or fetal medical indications
• EGA
• PROM/PPROM
INDUCTION OF LABOR
Bishop Score
0
1
2
3
Dilation
Closed
1-2
3–4
>5
Effacement
0 – 30
40 – 50
60 – 70
> 80
Station
-3
-2
-1
+1, +2
Consistency
Firm
Medium
Soft
Position
Posterior
Mid
Anterior
INDUCTION OF LABOR
Oxytocin
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•
Peptide from posterior pituitary
Usually given IV; can be given IM
IV bolus = hypotension
10 units/ml; dilute in 1000 cc LR
Routine dose: Start at 2mu/min,
 2 mu/min every 15-30 minutes to 36 IU/min
• Active management of labor: start at 6 mu/min,  by
6 mu/min every 15 minutes to 36 mu/min
• High doses – ADH effect = water intoxication
INDUCTION OF LABOR
Misoprostol (Cytotec®)
• PO tablet FDA approved to prevent gastric
ulceration in patients taking NSAID’s
• PGE1
• 25 mcg (1/4 of 100mcg tablet) in vagina Q 4
hours X 4 doses
• Wait 6 hours after last dose to start oxytocin
• Contraindicated with uterine eschar
NORMAL LABOR & DELIVERY
Foley Bulb
• Place special foley through cervix and inflate
balloon to 30 cc
• Tape to thigh – remove by 12 hours
• Used when Cytotec contraindicated –
previous uterine incision
• Mechanism: mechanical/local release of
prostaglandins
• Frequently used with pitocin
Other things to consider
•
•
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Maternal pain relief
GBS status
Twins/Multiple
Breech
Caesarean delivery
VBAC
NORMAL LABOR & DELIVERY
Anesthesia/Analgesia
• Cesarean section
– Spinal
– Epidural
– General (more risky in obstetrics)
• Vaginal delivery
– IV pain meds
–
–
–
–
Local
Pudendal
Epidural
Combined spinal/epidural
Pudendal Block
GBS Protocol
• Routine culture at 35-37 weeks
• Culture lower 1/4 vaginal and perianal area
• Culture stable up to 96 hours in
Amies transport media
• If patient allergic to penicillin, get
susceptibility testing
GBS Epidemiology
• 10-30% of pregnant women colonized
• Vertical transmission may occur
• Neonatal invasive GBS infection
decreased 21% from 1993 to 1998.
• In 2000 rate was .23 per 1000 live births
• Early onset infection
– Antibiotics in labor will reduce
– Prevents 225 newborn deaths per year
• Late onset infection
Multiple Gestation
• Twins
– Vertex/vertex – vaginal delivery
– Vertex/breech or transverse lie – breech extraction
of 2nd twin
– Breech/other – C-section (locked twins)
• Triplets or higher order gestation
–
Cesarean delivery indicated
NORMAL LABOR & DELIVERY
Breech Presentation
• 37 weeks gestation – external cephalic
version (50% success)
– Ultrasound
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Non-stress test
IV/subcutaneous terbutaline for tocolysis
Ultrasound monitoring
Repeat non-stress test
• Cesarean section vs. vaginal birth
BREECH
Frank breech
Complete breech
Incomplete breech
NORMAL LABOR & DELIVERY
Cesarean Delivery
Other
14%
Breech
12%
Fetal
Distress
9%
Repeat C/S
35%
Dystocia
30%
VBAC/Trial of Labor
• One previous LTCS (1% rate of
rupture)
• Two previous LTCS (2% rupture)
• Unknown incision (up to 7% rupture)
• Success of TOLAC = VBAC (vaginal
birth after cesarean section): 60 – 80%
USA TRENDS