4. Labor and Birth

8/13/2019 4. Labor and Birth

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Normal

Labor and

Birth

The Five “Ps” of Labor

o Passageway: maternal

bony pelvis and tissues

o Passenger: the fetus

o Powers: primary and

secondary forces of labor

o Position: maternal

position

o Psyche: psychological

component of mother

The Passage

o Pelvis type

o Pelvis size

o Cervical effacement

o Cervical dilation



Cervical Effacement and Dilation

o Uterus divides into upper(contractile) and lower

(passive) segments.

o Effacement: taking up of

internal os and cervical canal

into uterine side walls

o Dilatation: Widening of

cervical os from opening < 1

cm to approximately 10 cm.

Formation of Lower Uterine Segment

Primigravida: Effacement usually occurs before dilation

Multipara: dilation & effacement usually occur together

The Passenger

o Fetal head

o Fetal attitude

o Fetal Lie

o Fetal presentation

o Fetal position



The Passenger: Fetal Head

o Skull vault bones

§ 2 - Frontal

§ 2 - Parietal

§ 1 - Occipital

o Sutures

§ Sagittal

§ Frontal

§ Coronal

§ Lambdoidal


Molding of the fetal head in cephalic positions


o Landmarks

§ Mentum (Chin)

§ Sinciput (Brow)

§ Anterior Fontanelle(Bregma)

§ Vertex

§ Posterior Fontanelle

§ Occiput



The passenger: The Fetal Head

Anteroposterior diameters

of the fetal skull

Transverse diameters

of the fetal skull

Passenger: Fetal Attitude

o Relation of fetal parts to

one another

o Normal attitude is flexion

of neck, arms and legs

o Hyperextension is

abnormal attitude

o Fetal attitude changes can

cause larger diameter of

fetal head to present to

pelvis

Passenger: Fetal Lie

o Relationship of longitudinal axis of fetus

to longitudinal axis of mother

§ Longitudinal lie: fetal spine is parallel tomother’s spine

l Transverse lie: fetal spine is at right angles tomother’s spine

l Vertex (head first) is most common, but

breech (buttocks or feet first), transverse

(laterally across uterus) and oblique

(diagonally across uterus) also possible



Passenger: Fetal Presentation

o Presentation refers to fetal part entering pelvis first

o Most common is cephalic but breech and shoulder

also occur.

o Cephalic presentations: vertex, military, brow or

face

o Breech presentations: complete, frank or footling

o Shoulder presentation: occurs rarely; presenting

part is shoulder, arm, back, abdomen or side

Passenger: Cephalic Presentations

o Vertex§ Most common

§ Head completely flexed

§ Smallest diameterpresents

§ Occiput is thepresenting part

o Brow§ Partially extended§ Largest diameter

presents§ Sinciput is presenting

part

o Face

§ Hyperextended

§ Small diameterpresents

§ Face is presenting part

o Military

§ Neither flexed orextended

§ Larger diameterpresents

§ Top of head is

presenting part

Passenger: Malpresentations

o Complete Breech

§ Fetus sitting with legscrossed in pelvis

§ Knees and hips areflexed

§ Buttocks and feet arepresenting part

o Frank Breech

§ Hips are flexed withknees extended

§ Buttocks are thepresenting part

o Footling Breech

§ Hips and legs areextended

§ Feet are the presentingpart

§ Can be a double orsingle footling

o Shoulder Presentation

§ AKA transverse lie

§ Presenting part isshoulder, arm, back,abdomen or side



Passenger: Fetal Position

o Fetal landmarks of presenting fetal part to are used todescribe position of fetus in relation to the front(anterior), back (posterior), or sides (right or left) of maternal pelvis.

Fetal Landmarks

l O = Occiput (vertex)

l M = Mentum (face)

l S = Sacrum (breech)

l A = Acromion process

(shoulder)

Maternal Pelvis

l R = Right side

l L = Left side

l A = Anterior

l P = Posterior

lT = Transverse

Categories of Presentations

ROA= Right Occipital

Anterior

LOA= Left Occipital

Anterior

LOT = Right Occipital

Transverse



Categories of Presentations

ROP= Right Occipital

Posterior

LMA= Left Mentum

Anterior

LSP = Left Sacrum Posterior

o Relationship of presenting partto imaginary line drawnbetween ischial spines of maternal pelvis

o Ischial spines mark narrowestdiameter through which fetusmust pass

o The station at the level of ischial spines is 0

o If presenting part is higher thanspines, it is a negative number.

o If presenting part is lower than

spines, it is a positive number.

The Passenger: Fetal Station

Passenger: Engagement

› Engagement occurs when largest diameter

of presenting part reaches pelvic inlet and

can be felt on vaginal exam

› Floating: If presenting part directed

towards pelvis but can easily be moved out

of inlet› Ballotable: When presenting part dips into

inlet but can be displaced with upward

pressure from examiner s fingers

› Engaged: If presenting part fixed in pelvic

inlet and cannot be dislodged



The Power:Uterine

Contractions

Power: Forces of Labor

o Primary forces are involuntary contractions of

uterine muscle fibers, stimulated by

pacemaker in upper uterine segment

o Secondary forces consist of the voluntary use

of abdominal muscles during the second stage

of labor to facilitate the descent and delivery

of the fetus

Power: Primary Forces of Labor

o Effacement:

§ With each UC, muscles of upper uterine segmentshorten, exerting longitudinal traction on cervixcausing thinning and drawing up of internal os andcervical canal into uterine side walls

§ Measured from 0 to 100%o Dilation (aka dilatation)

§ As uterus elongates with UCs, fetal bodystraightens out and exerts pressure against loweruterine segment and cervix. Cervix opens as aresult, allowing for birth of fetus

§ Measured from 0 to 10 cm



Power: Primary Forces of Labor

Position of Laboring Woman

o Affects: circulation, fatigue,comfort

o Upright position (walking,sitting. kneeling, squatting)

§ Promotes descent of fetus

§ Improves blood flow

§ Relieves backache

§ Straightens axis of birthcanal

§ Increases pelvic outlet

Psyche

o Preparation for childbirth

o Sociocultural heritage

o Previous childbirth

experience

o Support from significantothers

o Emotional status

o Environmental influence



Premonitory Signs of Labor

o Lightening

o Bloody show

o Painful Braxton Hicks

o Cervical ripening

o Diarrhea

o Energy burst

False vs True Labor

False Labor

o Regular contractions

o Decrease in frequency andintensity

o Discomfort in lowerabdomen and groin

o Activitychange alters Ucs

o UCs stop when sleeping

o No appreciable cervicalchange

o Sedation decreases UCs

o Show usually not present

True Labor

o Regular contractions

o Progressive frequency andintensity

o Discomfort begins in back,radiating to abdomen

o Activity increases UCs;continue when sleeping

o Progressive effacement anddilation of cervix

o Sedation does not stop UCs

o Show usually present

Leopold’s First Maneuver



Leopold’s Second Maneuver

Leopold’s Third Maneuver

Leopold’s Fourth Maneuver



Stages of Labor and Birth

o First stage:begins with onset of true labor and ends

with complete dilation

o Second stage: begins with complete dilation and

ends with birth of infant

o Third stage: begins with expulsion of infant and

ends with expulsion of placenta

o Fourth stage: begins with expulsion of placenta,

lasting 1 to 4 hours

First Stage of Labor

Latent Phase

§ Cervical dilation: 0 - 3 cm

§ Duration: 8.6 hrs in nullipara - 5.3 hrs in multipara

§ Contraction frequency: 3 - 30 minutes; may beirregular

§ Contraction duration: 30 - 40 seconds

§ Contraction intensity: Mild by palpation, 25 - 40 mmHg by IUPC

§ Physical sensations: Menstrual-like cramps, lowbackache, light bloody show, diarrhea, possible SROM

§ Maternal behavior: Able to ambulate and talk through

contractions; pain controlled fairly well

First Stage of Labor

Active Phase

§ Cervical dilation: 4 - 7 cm

§ Duration: 4.6 hrs in nullipara - 2.4 hrs in multipara

§ Contraction frequency: 2 - 5 minutes


§ Contraction intensity: Moderate to strong by

palpation, 50 - 70 mm Hg by IUPC

§ Physical sensations: Increasing discomfort, trembling

of thighs/legs; pressure on bladder and rectum;

backache with occipitoposterior fetal position.

§ Maternal behavior: Working to keep control; quieter



First Stage of Labor Transition

§

Cervical dilation: 8 - 10 cm§ Duration: 3.6 hrs in nullipara - variable in multipara

§ Contraction frequency: 1.5 - 2 minutes


§ Contraction intensity: Strong by palpation, 70 - 90 mm

Hg by IUPC

§ Physical sensations: Increased bloody show; urge to

push; increased rectal pressure, ROM may occur.

§ Maternal behavior: Ambulation difficult; may be

irritable, agitated; self-absorbed; needs more support;

may feel discouraged and unable to cope

Cardinal Movements of Labor

o Descent

o Flexion

o Internal Rotation

o Extension

o Restitution

o External Rotation

o Expulsion


o Adaptations made by fetus to maneuverthrough pelvis during labor and birth.

o In occiput (most common presentation),movements occur in following order:

1. Engagement of presenting part occurs

2. Descent of fetus into pelvis3. Flexion of fetal head (often occurs with

descent)

4. Internal rotation of fetal head toaccommodate widest diameter of maternalpelvis




5. Extension of fetal head as it comesunder symphysis

6. Restitution as head turns 45˚ to untwistneck

7. External rotation viewed as head turns45˚ to align shoulders with widestdiameter of maternal pelvis

8. Expulsion as anterior shoulder slipsunder pubis

Second Stage of Labor o 10 cm to birth

o Duration: up to 3 hrs in nullipara and 0 - 30 min inmultipara

o Contraction frequency: 2 - 3 minutes

o Contraction duration: 40 - 60 seconds

o Contraction intensity: Strong by palpation, 70 - 100 mmHg by IUPC

o Physical sensations: As presenting part descends, urge to push increases; increased rectal and perineal pressure;sensation of burning, tearing and stretching of vagina and perineum

o Maternal behavior: Excited and eager to push; reluctant,ineffective pushing

Lacerations

o Lacerations to perineum or surrounding tissue may

occur during childbirth; 3rd and 4th˚ lacerations most

commonly occur after midline episiotomy performed

§ 1st˚ involves only epidermal layers; if no bleeding

may not need repair§ 2nd˚ involves epidermal and muscle/fascia

involvement requires suturing

§ 3rd˚ extends into rectal sphincter

§ 4th˚ extends through rectal mucosa



Third Stage of Labor

o Birth of infant to birth of placenta

o Duration: 5 - 30 minutes

o Physical sensations: Mild

uterine contractions; feeling of

fullness in vagina as placenta

expelled

o Maternal behavior: Attention

focused on newborn; feelings of

relief; euphoria

Apgar Score

o Quick method to assess fetal adaptation toextrauterine life

o Five criteria scored at 1 and 5 minutes after birthwith 0,1 or 2 pts given for each criteria

§Appearance: Color

§ Pulse: Heart rate

§Grimace: Reflex irritabilty

§Activity: Muscle tone

§Respirations: Respiratory effort

o ≥ 8: minimal intervention

o 4-7: suction, tactile stimulation, oxygen

o 0-3: resuscitation

Placental Separation

o Uterine contraction after birth of infant diminishes

surface area of placental attachment, causing

placenta to begin to separate.

o Bleeding occurs causing hematoma to form

between placenta and uterine wall

o Signs of separation:

1. Globular-shaped uterus

2. Gush of blood

3. Rise of fundus

4. Protrusion of umbilical cord



Placental Separation

Placental Delivery

o When signs of separation appear:

§Ask woman to bear down

§ If undelivered, firm, gentle traction applied to cordwith pressure on fundus

§ Shiny Schultz: Separation occurs from inner toouter margins of placenta allowing fetal side todeliver first

§Dirty Duncan: Separation occurs from outermargins first, causing placenta to roll up withmaternal surface first.

§ Considered retained when 30 minutes have elapsed

without delivery of placenta

Fourth Stage of Labor

o One to four hours following birth

o Tremendous hemodynamic changes occur

o Blood not lost at birth (250 - 500 ml) isredistributed into venous beds

o B P drops, pulse increaseso Uterus is contracted and is midline

o Fundus is usually midway between umbilicus andsymphysis pubis

o Shaking chill is common

o Hypotonic bladder may lead to urinary retention

Documents

4. Labor and Birth