LABOR & DELIVERY
Lecture 6
Introduction
Uterus: pear-shaped muscle made of 3 layers:
Endometrium – inner lining - shed during menses.
Myometrium - muscle layer – middle
Perimetrium - outer layer -extra support to whole
structure.
THEORIES of LABOR:
Combination of factors start labor:
Oxytocin & prostaglandin - most important
biochemical factors in stimulating uterine
contractions.
Estrogen ↑ uterus response & progesterone ↓ it.
THEORIES:
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Oxytocin Stimulation: Term uterus sensitive to
oxytocin ↑ d/t pressure exerted on cervix by
fetus.
Progesterone Withdrawl: ↓ progesterone by fetus
& ↑ prostaglandins in chorioamnion results in ↑
uterine contxs.
Estrogen Stimulation: ↓ progesterone allows
estrogen to ↑ contractile response of uterus.
Fetal Cortisol: Changes biochemistry of fetal
membrane: ↓ progesterone & ↑ prostaglandin in
placenta.
Distention: uterine muscles stretch causing ↑
prostaglandin.
Amniotic membranes (sac) makes arachidonic
Acid → Prostaglandin - ^ uterine contractility.
Premonitory signs of labor: weeks before real labor
AKA “False Labor”
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Lightening: Fetus settles into pelvic cavity.
Braxton-Hicks: Irregular intermittent contractions; “false
labor”; DO NOT initiate true labor.
Cervical changes: cervix effaces [thins] & dilates slightly
Baby's head in pelvis pushes against cervix causing
relaxation and effacement.
Burst of Energy: Nesting instinct; cleans house, sets up
nursery. ↑ epinephrine resulting from ↓ progesterone
Cervix in posterior position.
Signs True Labor: closer to time of delivery
Uterine Contractions: regular & frequent compared to
Braxton-Hicks. Stronger w. time.
 Bloody Show: pink tinged secretions d/t softening
cervix.(aka mucous plug)
 Rupture of Membranes: (ROM) Labor in 24 hrs.
Multiparas sooner. Big gush or slow trickle.
 Clear/odorless. Green/brown, danger sign
 Meconium aspiration > distress/infection.
 Immediate medical attention.
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PROM or prolonged ROM – intrauterine infection
[pathogens reach fetus]
Difference Between True & False Labor:
True Labor
A. regular contx’s
B. discomfort begins in back & spreads to abdomen.
C. progressive cervical dilation/effacement
D. Interval between contx.’s become shorter
E. intensity of contx.’s ↑ with ambulation
F. contx.’s ↑ in duration & intensity
False Labor
A. irregular contx.’s
B. discomfort localized in abdomen
C. no change
D. No change
E. Ambulation has no effect
F. No change
“STAGES of LABOR”
4 in All !
First Stage
Onset of true labor to complete dilation = 10 cm.
~ 6-18 hrs. primapara; 2-10 hrs. multipara.
Cervix becomes more anterior.
3 phases: Latent, Active, Transitional.
Latent: Dilation 0-3 cms. Contx.’s mild/irregular.
Active: 4-7 cms. Contx.’s 5-8 min. apart.
Lasts 45-60 sec; moderate - strong intensity.
Transitional: Dilation 8-10 cms. Contx.’s 1-2
min. apart; 60 –90 sec.; strong intensity.
No pushing til fully dilated.
Second Stage: “Birthing of Baby”
Delivery of infant:
up to 1 hr. or ~ 20 contx’s – primip.
20 min. or ~ 10 contx’s in multip. Can last up to 3 hrs.!
Cardinal movements occur here.
Most difficult & uncomfortable part of labor.
Crowning occurs at +4 -+5 station.
Strong urge to push & bear down as infant passes through
vagina & rectum – may have BM.
Positions: Sitting, Side Lying, Standing, Squatting, All Fours,
Kneeling.
“Crowning” - External view
“Cardinal Movements” - Internal motions
Third Stage
Delivery of placenta ~ 5 - 30 min.
Separation should be automatic [uterus contracts & mom
bears down]
Don’t palpate non-contracted uterus –possible eversion.
Maternal vessels still open.
MD/MW presses on contracted uterus. “ Crede’s
Maneuver”
Pitocin > placenta delivered to avoid retained placenta.
If no spontaneous delivery of placenta, manually removed.
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Antibiotics
Fourth Stage
Placenta out; mother recovers in “LDR”
“Labor, delivery, & recovery”
Lasts ~ 1 hr. unless complications arise.
Then pt. transferred to PP unit.
Nursing Interventions During Labor
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Triage - Admit client to birthing area
[MD determines true labor]
Emotional support & encourage rest
 Progress of labor
 Monitor/document contractions & FHR q 15 min.
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Monitor/document maternal VS q 1 - 4 hr
 Assess
pain & provide pain relief as
prescribed .
Nursing Interventions Cont.
* Provide comfort measures [back rub, ice chips]
* Explain equipment & procedures.
* Observe & document time of ROM
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Supine hypotension – Position on side - pressure
off vena cava
Role of coach during active/transitional stages
Assist with pushing during 2nd stage.
Record time of delivery, Apgar score,
spontaneous cry, & resuscitative efforts to infant
Monitor infant for extrauterine life adjustment
Encourage family bonding > delivery
Breathing Techniques
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Slow chest: 6-12 “easy” breaths/min. Used in early labor.
Combination: quicker, lighter breaths
Used during active labor; one slow breath in beginning &
quicker breaths to follow.
Pant-Blow: 3 - 4 quick breaths, with forceful exhalation.
Used @ end of 1st stage when contx.’s strongest.
Elimination
Monitor UO q 2-4 hr.
Pressure of fetal head reduces bladder tone.
Full bladder > inhibits labor.
Catheterize. Remove > delivery.
Hydration
IV to hydrate; pt. diaphoretic & NPO x ice chips.
Lactated ringers; good volume expander.
Assessing Progress of Labor
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Dilation: 0–10 cm. [opening cervix]
Effacement: 0 –100 % [thinning cervix]
Station: Relationship of presenting part to pelvic
ischial spines -midway in pelvic cavity.
“0 ” station aka “engaged”.
-1 to -5 above “0”
+1 to +5 (outlet) below “0”
+4/+5: baby's head out.
Mechanism of Labor: passage of fetus thru birth
canal involves position changes called: Cardinal
Movements of Labor: mechanical & spontaneous. “2nd stage”
Engagement: presenting part enters midpoint of pelvis @
ischial spines.
Descent: downward movement thru pelvic inlet,
thru dilated cervix, reaches posterior vaginal
floor. Mom feels like pushing. Widest part [head] passed
thru pelvis. “active forces of labor.”
Flexion: pressure from pelvic floor causes head to
flex towards chest; chin touches chest.
Internal Rotation: occiput [back of head] in
diagonal position & rotates towards face down
position. / to ↓ (occurs as body parts press on bony pelvic
structures)
Extension: top of head delivered & extends as
face & chin are delivered.
External Rotation: head rotates back to
previous lateral position. Rest of body is
delivered.
Factors affecting labor process:
4 P’s [Powers of Labor]
– Passenger
– Passageway
– Powers
– psyche
Passenger: [infant]
Fetal head: widest part of body; most difficult to pass
thru vaginal canal; passage depends on bones, sutures,
fontanelles.
Cranium - 8 bones meet @ suture lines
Cranial bones move & overlap, allows skull to pass thru
birth canal.
Fontanelles: soft spaces created by junctures of suture
lines - covered by membranes; compress during delivery
to aid in passage of fetus.
“Molding” of infant head.
Passenger cont.
Skull widest @ antero-posterior diameter [front
to back] than @ transverse diameter [across].
 Antero-posterior diameter measures differently
@ different locations.
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Occipitomental diameter- widest - measured from chin to
posterior fontanelle = 13.5 cm
Smallest diameter - lower occiput to anterior fontanelle
(suboccipitobregmatic) = 9.5 cm
Complete flexion allows smallest diameter of fetal
skull to enter pelvis most easily.
B. Fetal Attitude: degree of flexion of fetal
head; chin touches sternum.
Complete flexion: allows smallest diameter of skull
to pass thru pelvic cavity. Best position!
Moderate flexion: head less flexed making
diameter wider (aka military or neutral)
Poor flexion: brow or face presentation; presents
skull diameter too wide making delivery difficult.
Friedman’s Curve
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Friedman's Curve describes progress of two variables
over time: dilation of cervix and descent of baby.
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Labor is “dysfunctional” when cervix stops dilating or
fetal descent stops or both.
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Possible diagnosis of "failure to progress"
C-section indicated.
Maybe due to CPD (cephalo pelvic disproportion or
epidural anesthesia (can slow labor).
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C. Fetal lie: [position of fetus in utero] relationship of long
axis of fetus [spine] to long axis of mother:
1. Longitudinal – vertex/breech; vertical in
relation to mom; ~ 99%.
2. Transverse – horizontal in relation to mom; < 1 %.
C/S; ^ in grand multip – stretched uterine muscles; try
version.
3. Oblique - diagonal
D. Fetal presentation: part of fetal head enters pelvis;
1. Cephalic 95.5%
2. Breech 3.5%
3. Face 0.3%
4. Shoulder 0.4% [transverse lie]
E. Fetal position: “occiput is landmark”
Described in 3 letters:
1st : presenting part in relation to mother’s R or L.
Middle: presenting part [occiput, mentum, sacrum]
Last: landmark is anterior, posterior, transverse in relation
to mother’s spine. Anterior (A) back of head against
symphysis pubis & face towards spine. Posterior (P) Back
of head = mother’s spine; painful contxs. Transverse (T)
= fetus sideways.
Common positions in vertex presentations: *LOA, ROT,
ROP, ROA, LOT, LOP.
Passageway:
Refers to fetus passing thru uterus, cervix, vaginal
canal. Single most important determinant to mechanism
of labor.
A. 4 Types of pelvis:
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1. Gynecoid – 50% of women; rounded, oval
shape; easy vaginal delivery; considered “normal
female pelvis”
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2. Android – 20 % of women; vaginal delivery difficult;
prob. C/S; “true male pelvis”
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3. Anthropoid – oval; assisted vaginal birth usually with
forceps; 20-25%
Platypelloid – < 5 % of women;
flattened pelvis; vag. del. difficult
 4.
B. Structure of Pelvis: bones held together by
ligaments. Supports/protects organs inside.
False Pelvis: Outer - broader. Hip bones.
True Pelvis: Internal – narrower. Holds bladder, rectum, &
reprod. Organs.
True pelvis - 3 parts - inlet, midpelvis, outlet.
[Most important in childbirth]
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If pelvis too small, home birth not done.
CPD - cephalopelvic disproportion > C/S.
PELVIC INLET:
Antero-posterior diameter - front to back ~ 12.5
cm. (diagonal conjugate)
True conjugate - actual opening of outlet.
Subtract width of symphysis pubis [1.5 cm] from
diagonal conjugate. 12.5 – 1.5 = 11.0 cm.
(complete flexion = 9.5cm diameter)
Transverse diameter [across] ~ 13.5 cm
MIDPELVIS: narrowest part of pelvis that fetus
must pass through - “ischial spines”
PELVIC OUTLET: Trouble passing through pelvic
opening, pelvis too small or poor fetal attitude.
Soft Tissue: Ligaments, Uterus, cervix, vaginal
canal
Powers:
 Uterine contx’s: primary force moving fetus thru
maternal pelvis during 1st stage of labor.
 Maternal Efforts: woman adds voluntary pushing
force to force of contx.’s during 2nd stage of
labor to propel fetus thru pelvis.
Psyche:
Psychologic Response to birth process:
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Prepared for childbirth - Childbirth classes-Prenatal care.
Previous childbirth experience - Complicated?
Support from significant other - Separated? Marital
strain? FOB involved? Abuse?
Emotional status - anxious/depressed, drug use, psych
hx
Culture - background may influence response to pain.
Some moan, some stoic, some verbally expressive.
Fear/anxiety exacerbate pain → uterine dysfunction &
ineffectual labor & posttraumatic stress disorder
Maternal/Fetal Evaluation
During Labor
With Electronic
External/Internal
Monitoring
EFM “electronic fetal monitoring”
Measures:
Fetal Heart Rate (FHR) and Uterine Contractions (UC)
External – Toco (UC) and Cardio (FHR)
• Toco transducer uses graph paper [60 sec intervals]
UC assessed for intensity, length, frequency.
• Abdominal palpation. Uterus hard then soft.
3 Phases of UC:
a. increment ↑
b. acme [peak]
c. decrement
As contractions intensify, labor progresses.
Vaginal Exam - dilation, effacement, station, &
presentation.
Assessment:
Intermittent - 20 minute tracing standard.
Continuous - for active labor or with complications.
Duration: beg. of contx. to end of same contx.
Lasts ~ 30 sec. [early] to ~ 60 sec. [active].
Frequency: beg. of one contx. to beg. of next.
~ q 5 -30 min. early labor; q 2-3 min. active labor.
Resting Tone: period of uterine rest bet. contx.’s.
Measure by palpation; internally measures ~10 mmHg.
Be Careful Not To….
 Rely
on verbal clues from mother regarding
contractions & labor progress.
 Misleading, giving false impression of good
labor pattern.
 Contractions may be more or less intense
than what pt. reports.
 RN may miss forceful contractions d/t
excellent coping skills or high pain tolerance
External Fetal Monitoring
Also Records:
Fetal Heart Rate (cardio transducer) FHR
Advantages:
Evaluates contractions & FHR
Provides written record of both
Disadvantages:
May be inaccurate due to maternal/fetal
movements.
Need experienced clinician to read otherwise info
can be misinterpreted.
Internal Monitoring
More Accurate !
Fetal scalp electrode: wire electrode attached to scalp of
fetus -monitors FHR accurately & continuously.
Advantages: precise assessment of FHR; not affected by
fetal movement.
Disadvantages: lacerations of fetal scalp, mom can’t
ambulate.
IUPC -intrauterine pressure catheter inserted into
uterine cavity to monitor contx.’s
precisely/continuously.
Advantages: precise assessment of maternal
contractions. Mom can turn side to side.
Measures Intensity: “strength” of UC internally
[30-50mmHg during peak of contx]
Disadvantages: ↑ risk of maternal infection, mom can’t
ambulate.
Fetal Heart Rate
“Baseline” average fetal heart rate that occurs
between contx.’s during 10 min. period.
 Normal 110/120 - 160 [accels/decels not counted]
Bradycardia – FHR < 110 for 10 minutes;
<100bpm sign of fetal hypoxia; danger sign.
 Seen with prolapsed cord
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Tachycardia – FHR > 160 for 10 minutes.
assoc. with maternal temp. and infection such as
chorioamnionitis.
Variability [FHR] aka “Baseline Variability”
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“Fluctuations” in FHR. Normal & expected
finding. Should always be present; appears as “jitters”.
Clinical Significance- fetal well-being.
Caused by natural pacemaker ability of FH d/t
effects of sympathetic & parasympathetic
nervous system.
Nursing Interventions- cont. monitoring & assess
tracing q 15 min. Should show 6-25 bpm
fluctuations within one min. period.
120 → 135 “reassuring”
Main Causes of decreased variability include:
Hypoxemia/acidosis (due to fetal distress)
Fetal sleep cycles
Drugs (Analgesics, barbiturates, tranquilizers, anesthetics)
Prematurity
Arrhythmias
Fetal tachycardia
Preexisting neurological abnormality
Congenital anomalies
Decreased variability of FHR
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Nursing Interventions:
* accoustic stimulation to “wake” fetus
* Narcan
* Amnioinfusion - decreases cord comp; dilutes mec.
* Left/right lateral position or knee-chest; notify MD;
fetal scalp pH, possible emergency C/S; IVF, O2
“Flat tracing” or “minimal” aka non-reactive tracing
[pencil mark pattern] indicates fetal distress; must be
corrected or delivered ASAP. Experienced RN usually able
to determine reason for non-reactive tracing.
How Do Uterine Contractions Affect Fetal Heart Rate?
Uterine contractions can affect fetal heart rate by increasing or decreasing that rate in association with any given contraction.
The three primary mechanisms by which uterine contractions can cause a decrease in fetal heart rate are compression of:
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Fetal head compression
Umbilical cord compression
Uterine myometrial vessel compression
Decelerations: decreases in FHR.
Early deceleration of FHR- periodic ↓ in FHR
 Cause = head compression during contx.’s
 Shape= onset of decel to peak > than 30 sec.
 Nadir of decel (lowest point) & peak of contx. (highest
point) coincide. Mirror image of contx.
 Range= lasts as long as contx.; resolves with end of
contx. Occurs late in labor when head has descended.
 Clinical Significance= normal; if it occurs early in labor
before head fully descends, may be indication for
cephalo-pelvic disproportion [CPD].
Late deceleration of FHR:
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Cause= uteroplacental insufficiency or ↓ blood
flow thru uterus during contx.’s
Shape – nadir of decel. occurs > end of contx.
range - occur 30-40 seconds > contx. starts &
continue > contx. ends
clinical significance –needs immediate attention;
possible fetal distress. Could be d/t pitocin that is
causing hypertonic uterus.[ too many contx.- no
time for recovery]
Nursing Interventions:
-Left lateral position –takes pressure
off aorta & vena cava; ↑circulation to
uterus.
-↑ IV flow rate –↑ Circulation
–oxygen - face mask [5liters/min].
–D/C pitocin & document
–assist with fetal blood sampling
–[measures acidosis in fetus which
signifies hypoxia]
–Prepare for emergency C/S if decels.
persist
Variable deceleration of FHR
Cause: compressed umbilical cord
Shape – U or V shaped waves in FHR
Range –no pattern; occur in relation to contx.’s
Clinical Significance – fetus lying on cord; could be
dangerous if persist.
Occurs more > ROM [less fluid as cushion]
V = C variable decels = cord compression
E = H early decels = head compression
A = O accelerations = OK
L = P late decels = Placental insufficiency
Bradycardia = R/O prolapsed cord [emergency]!
Nursing Interventions
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– oxygen via face mask; IV fluids
– change maternal position; take pressure off
cord
– continue monitoring w.EFM
– follow hospital protocol: MD will do
amnioinfusion > ROM to supplement amniotic
fluid that’s left; provides fluid barrier to prevent
further cord compression.
Sterile, warm 500 ml NS/RL inserted into uterus
EFM observed for improved FHR pattern.
4. Accelerations of FHR: temporary abrupt increase in
FHR above normal baseline.
 cause- fetal movement; contractions *
 shape-FHR rises w. return to baseline; can occur @
same time as contx. or independently.
 Premie < 32 wks.; 10 bpm rise lasting 10 sec. ok
 32 wks. or >, 15 bpm rise baseline lasting 15 sec. ok
 ex. 135 ↑ to 150’s for 30 seconds.
 clinical significance: normal; signifies fetal well-being.
FHR meeting demands of labor process well.
Fetal Blood Sampling- assesses fetal hypoxia; from fetal
scalp [cervix dilated 3-4 cm]. Clean scalp w. iodine.
Results: 7.25ph > normal
7.20 -7.24 preacidotic
< 7.2 + acidosis; indicates hypoxia [↓ O2]
Role of Coach in Labor & Delivery
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emotional support
physical support – touch, massage
reduce anxiety
bonding with newborn as a couple
Obstetrical Procedures
Episiotomy: incision on perineum to
enlarge vaginal outlet. New trend: not done
routinely.
Types:
(in 2nd stage)
Median –vertical incision.
Medio-lateral –slanted to R/L of perineum; done
if tear anticipated.
Advantages: median or midline epis.
medio-lateral prevents tearing towards
rectum. Less chance of laceration.
Disadvantages: medio-lateral -longer
to heal.
Forceps: double bladed instrument to assist passage of
fetus. Not routinely done today.
When 2nd stage labor has stopped d/t epidural
 Infant in abnormal position; posterior position in birth
canal; macrosomia.
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[Outlet] Low forcep delivery: fetal head @ + 2, +3
station. Some anesthesia used.
Midforceps & High forceps: not done ^ birth trauma.
Cervical lacerations; Newborns > facial palsy or subdural
hematoma; forcep marks on face.
Vacuum Assisted Delivery:
disk shaped cup placed on scalp & vacuum
pressure applied; “pull” will deliver infant.
No anesthesia - fewer cervical lacerations.
Not done in preterm infants d/t soft skull.
Used in C/S.
Not used > scalp pH done; risk for hematoma
[vacuum pressure].
 Can cause caput for ~ 1 wk. Used
w.macrosomia.
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VBAC [vaginal birth after cesarean]
OK after low abd. incision; Not after classical
incision - risk for uterine rupture.
New Trend: not routinely done anymore. ** Pros & cons
1st baby: breech, fetal distress, pre-eclampsia
 Should space deliveries ~18 mos. apart. to
prevent rupture
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Types of Uterine Incisions:
Low transverse = Pfannenstiel = “bikini cut”.
Most desired & less visible. Right above pubic bone.
Vertical=classical incision. Visible scar; emergency
cases; “crash” C/S. Quick access to baby.
Cesarean Delivery ( C-section)
Major Indications for C/S:
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Active genital herpes or overgrowth of genital warts
HIV infection
CPD (cephalopelvic disproportion)
Severe HTN (toxemia)
Failure to progress with labor
Previous C/S with classical incision (vertical)
Placenta previa
Placental abruption –separation of placenta from uterus
Cord Prolapse; Macrosomia = large fetus
Breech positions; Fetal Distress & Transverse fetal lie
Induction of Labor: start labor. Goal: NSVD
Without Meds.- Natural
Amniotomy: Artificial ROM; amnio hook; break sac.
Monitor for poss.prolapsed cord.
Continue EFM. Usu.starts contx.’s & labor
progresses [@ 3 cm dilation]
With Meds. Pitocin drug of choice. 1/3 rd deliveries @
term in US done by induction. Reason: Life in uterus no longer
beneficial
*Fetal maturity 39 wks, post dates 41-42 wks.
*Cervical Readiness- ripe; ≥3 cm. dilated.
*Longitudinal lie; presenting part engaged
*Fetal Demise, Arrest of Labor
Induction - give Pitocin IVPB, ^ slowly as labor
progresses; shut off if contx’s too strong. Need MD
order.
Augmentation: assisting labor that’s in progress.
Pitocin used.
Contraindications:
Maternal: placenta previa; active herpes; structural
abnormalities; previous vertical uterine scar
Fetal: transverse or breech; fetal distress; premie.
Nursing Interventions:
IVF 10 units Pitocin in 1000 ml. RL
 Start rate @ 1 milliunit/min - pump
 Gradually ↑ to establish effective contx. pattern
 Monitor UC for frequency, rate, intensity
 Monitor FHR for signs of fetal distress
 Maternal BP, pulse, temp
 I&O
 Notify MD of progress
 Chart q 15 min on graph
 Prepare for delivery: radiant warmer, O2, suctioning,
 Hyper-stimulation of uterus; shut off pitocin as per MD.
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Bishop’s score: determines cervical readiness for
induction; looks at 5 factors. Score ≥ 8 favorable.
Multip can be induced @ 5
 Primip can be induced @ 7
Uterus/cervix should respond to induction.
Score < 5 low probability of success. Ripen cervix 1st.
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Bishop Scoring System - evaluates cervical readiness
for induction. 5 elements measured:
Score Cervical Cervical Station Cervical
Position
dilation effacement
consistency
_______cm.________%_______________________________
0
closed
0-30
-3
firm
posterior
1
1-2
40-50
-2
2
3-4
60-70
-1, 0
3
>5
>80
+1, +2
medium
mid
soft
anterior
Cervical Ripening: Artificial softening of cervix before
labor.
Prostaglandin gel 0.5mg.or dinoprostone 10mg.=[cervidil]
2-3 times q 12 for max. of 24 hrs.
* Done if cervix “unripe” or thick & undilated.