Week 4: Stages & Phases of Labor

What is Labor?

function of the patient by which the products of conception (fetus, amniotic fluid, placenta and membranes) are separated and expelled from the uterus through the vagina to the outside world

True Labor

• cervix: softens, effaces, dilates, moves anteriorly

• contractions: longer, stronger and closer together; worsen w/ activity; continue despite position change or comfort measures

• regular contraction pattern

• pain location: lower back radiating to lower abdomen

False Labor

• cervix: little to no change, posterior position

• contractions: intensity doesn’t increase; interrupted w/ meds, walking or position change

• irregular contraction pattern

• pain location: back or upper fundal area

Contractions from the [blank] help push the baby out

top bottom

Contractions from the [blank] keeps the baby in

sides

What contraction pattern indicates its time to go to the hospital?

contractions every 5 min, lasting >60 seconds for >1 hr

What Maternal Factors Lead to Labor Onset?

• Stretching of uterine muscles releases prostaglandins

• Pressure on cervix triggers oxytocin (Ferguson reflex)

• Increased estrogen and decreased progesterone ratios enhance UC

In labor initiation, a decrease in prostaglandins allows for…

increase in oxytocin which stimulates UCs

Ferguson Reflex

A positive feedback reflex during labor in which pressure from the fetal head on the cervix, vagina, or pelvic floor stimulates oxytocin release from the posterior pituitary. Causes stronger UCs, which further increase fetal pressure and oxytocin release until birth.

What Fetal Factors Lead to Labor Onset?

• Placental aging & deterioration stimulates UCs

• Fetal cortisol production reduces progesterone formation and increases prostaglandin

• Prostaglandins from fetal membranes stimulate uterine contractions.

Episiotomy

surgical incision made in the perineum during the second stage of labor to enlarge the vaginal opening and facilitate delivery

Uterus: Active Portion

contracts and helps push baby out

Uterus: Passive Portion

typically lower uterine section; stretches to help the baby come out

List the 5 P’s of Labor

1. Powers → strength of uterine smooth muscles

2. Passage → bony boundaries, the cervix and pelvis

3. Position of patient in labor

4. Psyche → patient’s emotional state determines response to labor and physiologic functioning

5. Passengers → fetus & placenta; affected by size, presentation, position, flexion

Effect of Maternal Cortisol on the Labor Process

moderate increase can help w/ labor progession; excessive maternal cortisol related to stress, anxiety, or fear can slow labor progression by slowing cervical dilation, ineffective contractions and causing vasoconstriction

Powers → Uterine Contractions

Force generated by the myometrium that dilates the cervix; most effective when consistent frequency & adequate intensity

Powers → Frequency

The time from the start of one contraction to the start of the next

Powers → Duration

The time from the beginning to the end of one contraction.

Powers → Intensity

• Strength of contractions

• 30-50mmHg per UC necessary for effective labor or >200 mmHg total in 10 min

• no more than 5 UCs in 10 min (>280 mmHg)

• impacted by pain/fear

Powers → Measuring Methods

• Palpation → always confirm w/ palpation ensuring cervix is resting between each UC

• Intrauterine pressure catheter (IUPC) → measures mmHg; associated w/ infection, trauma and uterine perforation

• External toco → measures frequency & duration NOT intensity

Tachysystole

>5 contractions in 10 min

Hypertonus

Contractions lasting longer than two minutes

Passage and Passenger → Cephalopelvic Disproportion (CPD)

Mismatch between fetal head and maternal pelvis that prevents vaginal delivery; should be reassessed as labor progresses

Pelvic Anatomy: Gynecoid

Most favorable pelvis for childbirth; round or transverse oval shape and adequate diameters

• favorable for vaginal birth

Pelvic Anatomy: Android

pelvis adequate for 20% of assigned males at birth; heart or wedge-shaped; reduced in all diameters; arrest of labor common

• not favorable for vaginal birth

Pelvic Anatomy: Anthropoid

ape like pelvis w/ incidence of 25%; long antero-posterior oval shape; OP presentation is common (sunny-side up)

• favorable for vaginal birth

Pelvic Anatomy: Platypelloid

flat w/ incidence of 5%; transverse oval shape; delay of descent at inlet common; c/s common

• not favorable for vaginal birth

Passenger → Fetal Lie

Relationship of the fetal spine to the maternal spine

• longitudinal, transverse, or oblique 

Fetal Presentation

The part of the fetus entering the birth canal first

• cephalic → head first

• breech → feet first

• shoulder

Fetal Presentation → Cephalic Vertex

most common and ideal presentation for vaginal birth; head fully flexed, with the chin tucked to the chest; allows the smallest diameter of the fetal head to pass through the pelvis

Fetal Presentation → Cephalic Military OR Sinciput

can still deliver vaginally; head is neutral aka “looking straight”; diameter is wider making descent slower/more difficult

Fetal Presentation → Cephalic Brow

cannot deliver vaginally; fetal head is partially extended, with the forehead (brow) presenting first; may require C-section

Fetal Presentation → Cephalic Face

vaginal delivery may be possible if chin is anterior; fetal head is fully extended, with the face as the presenting part; may require C-section if mentum posterior

Fetal Presentation → Breech Complete

vaginal delivery sometimes possible; fetus is flexed at both hips and knees, sitting “cross-legged”; risk of umbilical cord compression and birth injury

Fetal Presentation → Breech Frank

vaginal delivery possible but c/s recommended; hips are flexed and knees extended, so the feet are near the head; buttocks are presenting; most commo

Fetal Presentation → Breech Footling

c/s required; one or both hips and knees extended; single or both feet present first; high risk for cord prolapse and fetal injury

Fetal Presentation → Attitude

Degree of flexion or extension of the fetal body parts (ideal is full flexion)

Fetal Presentation → Position

The relationship of a fetal reference point (occiput, sacrum, mentum) to the maternal pelvis (e.g., ROA, LOA

Assessing Fetal Position → Anterior Fontanelle

Diamond-shaped, larger, soft area; closes by 18 months

Assessing Fetal Position → Posterior Fontanelle

Triangle-shaped, smaller area; closes by 6-8 weeks

Assessing Fetal Position → Occiput

back part of the fetal skull; point of reference when assessing fetal position specifically which way the baby is facing in the mother’s pelvis when the baby is in a cephalic (head-down) vertex presentation

Assessing Fetal Position→ LOA (Left Occiput Anterior)

back of the baby’s head (occiput) is pointing toward the mother’s left front side

• Baby’s Face: the mother’s right back side

• most common and ideal position for vaginal birth

Assessing Fetal Position→ Right Occiput Anterior

back of the baby’s head is pointing toward the mother’s right front side

• Baby’s Face: the mother’s left back side

• favorable position for vaginal birth

Assessing Fetal Position→ Left Occiput Posterior

back of the baby’s head is pointing toward the mother’s left back side.

• Baby’s Face: mother’s right front (up toward her belly button).

• Baby is “sunny side up.”

• Causes back labor (intense lower back pain)

• Labor may be longer or require position changes to help baby rotate anteriorly.

Assessing Fetal Position→ Right Occiput Posterior

back of the baby’s head is pointing toward the mother’s right back side.

• Baby’s Face: the mother’s left front side.

• leads to back pain and slower labor

• rotates to anterior position during labor, but may need maternal repositioning to assist.

Fetal Cardinal Movements Order

this is in the most ideal scenario:

• Engagement → Descent → Flexion → Internal Rotation → Extension → External Rotation (Restitution) → Expulsion

Fetal Station → Engagement

when the widest diameter of the presenting part has passed the inlet, usually station 0; comes after floating; rate at which this occurs dependent on number of previous deliveries

• if head not engaged, cord prolapse can occur

Fetal Station → Floating

presenting part is out of pelvis and freely moveable in inlet; comes before engagement; stations -3 to -2

Fetal Station → Descent

head moves deeper into pelvis; comes after engagement; stations +1 tp crowning

How Does Psyche Impact Labor?

fear related to past experiences (own or others); emotional readiness; stress; unwanted pregnancy and more all impact the labor process in a negative or positive way; as nurse you listen, educate, support

Nurs Interventions of 5 P’s → Powers

facilitate effective uterine contractions

Nurs Interventions of 5 P’s → Passage

minimize risk of infections, complications, etc

Nurs Interventions of 5 P’s → Position

facilitate maximum pelvic capacity

Nurs Interventions of 5 P’s → Passengers

facilitate fetal cardinal movements with position changes

Nurs Interventions of 5 P’s → Psyche

minimize anxiety & fear associated w/ labor; maximize coping strategies knowledge & understanding

Physical Assessment → Initial Admit

1. Complete Systems Assessment: review of systems, urinary protein + glucose (GDM, preeclampsia), Leopold’s to determine fetal position (ultrasound, SVE), fundal height, signs of preeclampsia, signs of domestic abuse/support

2. Evaluate for Risk Factors: review H&P (prenatal), prior OB hx, current pregnancy info

3. Ask about Labor Symptoms & Fetal Status: O2 status of patient/fetus, assessment of labor tolerance 

Physical Assessment → Ongoing

frequency dependent on labor progression, signs & symptoms but generally speaking:

• General assessment → hydration (I&Os q4hr), vitals (including FHR pattern + pain)

• Abdominal → contraction pattern, confirm uterine relaxation, pain NOT associated w/ contractions

• Vaginal → bleeding, discharge, ROM (time, color, odor), cervical exam (dilation, effacement, fetal station)

• Emotional → ongoing

How often should vitals be checked when in active labor?

q1hr

Frequency of Fetal Assessment w/ EFM → Low Risk w/o Oxytocin

• latent phase (<4cm): q1hr

• latent phase (4-5cm): q30min

• active phase (>6cm): q30min

• 2nd stage (passive fetal descent): q15min

• 2nd stage (active pushing): q15min

Frequency of Fetal Assessment w/ EFM → w/ Oxytocin OR Risk Factors

requires closer monitoring b/c process isn’t 100% natural

• latent phase (<4cm): q15-30min

• latent phase (4-5cm): q15min

• active phase (>6cm): q15min

• 2nd stage (passive fetal descent): q15min

• 2nd stage (active pushing): q5min

Hyperventilation in Labor

common w/ anxiety; can occur using relaxation breathing techniques; results in respiratory alkalosis

• symptoms: lightheadedness, dizziness, tingling of fingers, spasms in hands/feet, numbness

• nurs interventions: replace bicarb ions by rebreathing CO2 (breathing into cupped hands or paper bag)

Lab Values → Platelets & WBCs

• platelets → decreased at term due to hemodilution and increased consumptions

• WBCs → increase during labor (~25,000) b/c body experiencing trauma

Stages of Labor → 1st (Latent Phase)

cervix dilated 0-6cm; contractions (mild to moderate) transitioning from irregular to regular (q5-30min, lasting 30-45 seconds); longest phase

• maternal response: excited, talkative, eager; may be anxious about the start of labor

• nurs interventions: assist w/ positioning, monitor maternal/fetal status, integrate support persons (doula, family, etc), implement pain management, monitor I&Os, implement infection prevention measures

Stages of Labor → 1st (Active Phase)

cervix dilated 6-10cm; contractions (moderate to strong) (q2-5min, lasting 45-60 seconds)

• maternal response: serious, focused, and less talkative; may feel anxious or fatigued

• nurs interventions: assist w/ positioning, monitor maternal/fetal status, integrate support persons (doula, family, etc), implement pain/comfort management, monitor I&Os, implement infection prevention measures; prepare for delivery

Stages of Labor → 2nd

cervix dilated 10cm; contractions (strong) (q2-3min, lasting 60-90 seconds); ends w/ delivery of baby

• maternal response: intense focus on pushing; may feel relief when allowed to push; sense of control alternates with fatigue

• nurs interventions: encourage rest during latent phase, optimize oxygenation (open glottis pushing, side-lying, push every other UC), monitor FHR, prepare for newborn care + skin-to-skin contact, resuscitation equipment ready

Stages of Labor → 3rd

known as delivery of placenta

• nurs interventions: facilitate bonding (skin to skin), observe for signs of placental separation, monitor for increased bleeding (hemorrhage), inspect placenta for abnormalities

Stages of Labor → 4th

known as recovery/postpartum phase (1-4hr); focus on maternal stabilization, bonding and initiation of breastfeeding

• nurs interventions: monitor VS/fundus/lochia (Q15 min for 1 hr, Q30 min × 2 until stable), QBL (weigh pads, 1mg = 1mL), oxytocin (IV/IM) for hemorrhage prevention, fundus should be firm and midline at or below umbilicus; assess bladder function, encourage voiding, evaluate perineum using REEDA, assess/manage pain, monitor for signs of hemorrhage or infection

Signs of Placental Separation

Gush of blood, lengthening of cord, change in shape of fundus

• Shiny Schultz: fetal side of the placenta

• Dirty Duncan: maternal side of the placenta

QBL for Hemorrhage

≥ 500 mL

What Reflex Might be Suppressed due to Pitocin

Ferguson reflex

Open-Glottis Pushing Technique

Encourages exhalation during pushing to maintain oxygenation and reduce maternal/fetal hypoxia compared to Valsalva pushing; can lead to low APGARs

• discourage breath-holding

• limit pushing to 3x per contraction for 6-8 seconds each