L6 CH13

what factors influence onset of labor?

1. uterine stretch

• more stretching → increase uterine contractility

2. progesterone withdrawal

• progesterone → keeps uterus relaxes

• decreased progesterone → increased uterine contractions

3. increased oxytocin sensitivity

• more oxytocin → increased contractions

4. increased release of prostaglandins

• prostaglandins help dilate the cervix & stimulate uterine contractions

what are the premonitory signs of labor?

• cervical changes (cervical softening, possible dilation)

• increase energy level (nesting)

  • a sudden burst of energy before labor

• braxton hicks contractions

  • felt at the top of the uterus

  • felt primarily in the abd & groin & spreads downward

• lightening (fetus descends into true pelvis → increase pressure on bladder & lower legs but decrease pressure on diaphragm)

• bloody show

  • blood tinged mucus from vagina d/t expulsion of cervical mucus plug

• spontaneous rupture of membranes

  • amniotic sac breaks & sudden gush of fluid

what does true vs false labor depend on?

depends on contraction timing, strength, discomfort, change in contraction activity, does it stay or go?

what is true vs false labor?

1. true

• regular, coming close together contractions strong w/ time

• starts in the back, radiates around towards the front of the abd

• position changes don’t affect contractions

  • GO to hospital if contractions are 5 minutes apart, lasting for 1 minute each, for 1 hour

2. false

• irregular, not close together contractions

• weak & does not get stronger OR alternates between weak & not strong

• usually felt in the front of the abd

• may stop or slow down w/ hydration, rest, or position changes

  • If contractions diminish after fluids or movement = stay home

what are the five critical P’s factors affecting labor & birth? the additional 5 factors?

• critical 5 P’s

  • passageway (birth canal: pelvis & soft tissues)

  • passenger (fetus & placenta)

  • powers (contractions)

  • position (maternal)

  • psychological response

• additional 5 factors

  • philosophy (low tech → avoid unnecessary medical devices, high touch → hands on care)

  • partners (support caregivers)

  • patience (natural timing)

  • pt preparation (childbirth knowledge base)

  • pain control (comfort measures)

what is part of the passageway? what is the implications?

• bony pelvis & soft tissues

• implication: to assess pelvis for any abnormalities that hinders a vaginal birth

what is part of the bony pelvis?

• linea terminalis: division of false & true pelvis

• true pelvis (below linea terminalis)

  • inlet, mid-pelvis, outlet (pelvic measurements)

• false pelvis (above linea terminalis)

  • upper flared parts of 2 iliac bones & concavities

  • wings of base of sacrum

what is the purpose of pelvic examinations?

gets an idea if the baby will fit

for the bony pelvis, which type of pelvis: gynecoid, android, anthropoid, or platypelloid is considered favorable or not?

1. gynecoid → favorable for vaginal delivery

2. android → male shaped, not favorable

3. anthropoid → usually adequate

4. platypelloid → not favorable

what are the soft tissues in the passageway?

• cervix: thins through effacement (thinning) to allow presenting part to descent into vagina

  • if cervix is not effaced & you keep pushing → problem

• pelvic floor

• vagina

what are the components of passenger?

fetal skull, attitude, lie, presentation, position, station, engagement

what is the passenger: fetal skull? what is part of it? what is the implication?

• largest & least compressible structure, consists bones

• sutures: allows for overlapping & changes in shape (molding); helps identify position of fetal head

  • not fused & spaces (soft spots) → makes it possible for fetus to be born

• fontanelles: intersection of sutures, help in identifying position of fetal head & in molding

  • when doing cervical exam & you feel the fontanelle → ideal position

• diameters: occipitofrontal (head to forehead), occipitomental (chin to back of head) → the longest, suboccipitobregmatic (occiput to the anterior fontanelle) and biparietal (side to side width of skull)

• implication

  • sutures allow molding → reduces fetal head diameter

  • larger fetal head diameters → difficult birth

what is the passenger: fetal attitude? what is part of it? what is the implication?

• attitude: the relationship of fetal parts to itself (position of head, arms, legs)

• general flexion (optimal position)

  • baby’s head is down & near opening, feels fontanelle

  • back of fetus is round, chin flexed to chest

  • thighs flexed on the abd, legs flexed at the knees

  • arms cross over thorax

• extension

  • baby’s head is tilted/lifted backward

  • makes it harder to be born b/c of the diameter of the head

• implication:

  • any deviation from general flexion can cause difficulties w/ childbirth

what do dimensions have to do with the skull?

• depending on the position the fetus is in → it makes a smaller diameter on how the baby is delivered

• ex. occipitomental is 13.5 cm → when fetus is tucked it is 9.5 cm

what is the passenger: fetal lie? what are the types? what is the implication?

• fetal lie: relation of the spine of the fetus to the spine of the mother

• types:

  • longitudinal/vertical (up & down)

    • fetal spine is parallel to mother’s spine

    • ideal for vaginal delivery

  • transverse (sideways)

    • fetal spine is perpendicular to mother’s spine

    • not ideal for vaginal delivery

  • oblique (diagonal)

    • baby is not completely vertical or horizontal

    • not ideal for vaginal delivery

what is the passenger: fetal presentation? what does presentation & presenting part mean? what is the implication?

• presentation: the part of the body that enters the pelvic inlet first

  • cephalic (vertex) → head first

    • military → most favorable for vaginal delivery b/c baby’s chin is tucked to chest

    • brow → fetal head is neutral (neither flexed or extended), more difficult for passing

    • face → fetal head extended backward, baby’s face first

  • breech → butt or leg first

    • frank → buttocks first, knees extended to baby’s head

    • full or complete → buttocks first, knees bent (kind of sitting)

    • footling or incomplete → one or both feet first extending down, cord prolapse risk

  • shoulder first → associated w/ transverse lie

• presenting part: part of the fetal body felt first on exam

• implication:

  • cephalic → most favorable for delivery

  • breech & shoulder → c-section may be needed

what is the passenger: fetal position? what are the components? what is the implication?

• position: the relationship of the presenting part to the 4 quadrants of the mother’s pelvis

• three letters:

  • side of mother’s pelvis

    • right or left

  • presenting part

    • occipital (vertex)

    • mentum (face, chin)

    • sacrum (breech)

    • acromion process (shoulder, scapula)

  • relation to anterior, posterior, or transverse to the pelvis

    • anterior (toward pelvic bone)

    • posterior (toward the sacrum)

    • transverse (toward the side)

• implication:

  • determines how baby is going through the birth canal

what does a LOA & ROA mean? LOP stands for & what can it cause?

• LOA (more favorable)

  • left occipital anterior

  • back of baby’s head points toward left front pelvis

• ROA (more favorable)

  • right occipital anterior

  • back of baby’s head points toward right front pelvis

• LOA & ROA ARE FAVORABLE FOR VAGINAL BIRTH

• LOP

  • left occipital posterior → causes back labor bc back of head pushes against sacrum

  • on the mother’s left side, back of baby’s head, toward the mother’s back (sacrum)

what is the passenger: fetal station? what is the implication?

• station: the relationship of the presenting part to an imaginary line drawn between the ischial spines

• implication:

  • determines the progress of labor & how the baby is descending

what does -4, 0, and +4 mean in terms of fetal station? how are these usually reported?

• -4

  • the head is above the ischial spines in the false pelvis

• 0

  • baby’s presenting part is at the level of ischial spines → baby is engaged

  • engagement: largest transverse diameter of the presenting part has passed through the maternal pelvic brim into the true pelvis (largest diameter of the baby’s presenting part passes through inlet)

• +4

  • the baby’s presenting part is below the ischial spine → moving toward delivery

• usually reported in order of

  • dilation, effaced, station

  • ex.

    • 6 cm dilated, 80% thinned cervix, -4 station (station will change from negative to positive)

what are the 7 cardinal movements of labor?

• the movements that help the baby pass through during vaginal delivery

1. engagement & descent

• the biparietal diameter (greatest transverese diameter) is at or passes through the pelvic inlet & moves downward

• depends on pressure exerted by amniotic fluid, contractions, abd muscles, fetal’s body

2. flexion

• baby’s chin move towards chest → achieves smallest fetal skull diameter

3. internal rotation

• head rotates anteriorly in pelvis, moves towards opening

4. extension

• occiput passes through pelvis, back of next at pelvic arch (lifts chin to come out)

5. restitution

• head turns to realign with shoulders

6. external rotation/expulsion

• head rotates, shoulder engaged (anterior shoulder first then posterior)

what is powers? what are the 2 powers?

• powers is contractions (force that helps fetus move through birth canal)

1. primary (uterine contractions)

• involuntary uterine contractions (primary stimulus): mom can’t control them

• thin & dilates cervix

• effacement: thinning & shortening of cervix, measured in %

• dilation: 0-10 cm

2. secondary (maternal pushing)

• voluntary: mom actively pushes or bears down

  • do not effect cervical dilation, but important for expulsion of baby

• intra-abd pressure from mom pushing & bearing down

• ferguson relex: the urge to push

• three parameters to measure: frequency, dilation, intensity

what is the maternal positions about? what are some common birth positions?

• Impacts the biomechanics (positioning) of & physiologic (mother’s response) adaptations to labor

• Birth positions are described as upright, lateral, or supine 

  • Upright positions use gravity to bring the fetus down & lower risk of compressing maternal aorta that compresses blood supply & oxygen to the fetus

• Many benefits when you change positions & move around during birth b/c it can help with fetal descent 

  • Benefits of lateral/upright position:

    • Reduces length of first stage of labor & duration of second stage of labor 

    • Reduce assisted deliveries, episiotomies & perineal tears

    • Increase in comfort & reduce requests for pain medications

    • Enhances a sense of control

    • Allows gravity to move fetus downward 

what can childbirth do to someone psychologically? what can fear & anxiety do? what are the psychological responses influenced by? what factors influence positive birth experience?

• childbearing is a life altering experience & it can influence so many aspects of their life, including self-confidence, self-esteem, bonding, decisions, relationships, children

  • Fear & anxiety decreases a person’s ability to cope with labor

    • Fear & anxiety can cause maternal catecholamine secretion > inhibits uterine blood flow & perfusion

• influenced by

  • background, coping mechanisms, support system, preparation for labor, socio-cultural influence, positive-negative influences

• positive birth experience

  • clear info on procedures

  • support, not being alone

  • sense of mastery, self confidence

  • trust in staff caring for her

  • positive reaction to pregnancy

  • personal control over breathing

  • preparation for the childbirth experience

what are the physiologic responses to labor for the mother? (in terms of CV, blood, respiratory, GI, renal, neuro, endocrine, metabolic, musculoskeletal)

1. CV

• ↑ HR, CO, BP (during contractions)

  • CO pumps more blood to support needs

  • CO increases to 30-50% 2nd stage

• supine hypotension an occur when mom lies flat

2. blood

• ↑ WBC to about 25,000 during labor'

  • d/t stress hormones

3. respiratory

• ↑ RR & O2 consumption, hyperventilation

4. GI

• ↓ gastric motility, food absorption, gastric emptying & pH

• nausea, vomit, belching

5. renal

• difficulty voiding, paresthesia (tingling, numbness)

6. neuro

• increased endorphins → euphoria, amnesia, elation

• raises the pain threshold (so mom can tolerate pain) → usually not enough

7. endocrine

• ↓ progesterone (allows for contractions)

• ↑ estrogen, prostaglandins, oxytocin, metabolism (more energy is needed during labor)

8. metabolic

• ↑ BMR (body needs more energy during labor) & metabolism

• ↓ blood glucose (d/t incr. energy use & reduced food intake)

• ↑ temp (d/t physical exertion)

9. musculoskeletal

• muscle aches & cramps

what are the physiologic responses to labor for the fetus? (in terms of CV & blood, respiratory)

1. CV

• HR 110-160 bpm

  • provides info about oxygenation of fetus & placental blood flow

  • responds to changes in PCO2, PO2, & others

• 400 mL blood emptied from uterus back to mom per contraction

• periodic FHR acceleration & slight decelerations related to fetal movement, fundal pressure, contractions

  • decrease in circulation, perfusion, mild oxygenation to the fetus due to uterine contractions

• high hematocrit & hemoglobin to maximize oxygenation

2. respiratory

• surfactant secretion stimulated by labor

  • keeps alveoli open so baby can breathe after birth

• clearance of fetal lung fluid by absorption prior to birth & labor

  • just prior to labor catecholamine surge contributes to the absorption of fluid

  • during pregnancy fetal lungs are filled w/ fluid b/c they aren’t actually breathing → before & during labor the lungs absorb fluid d/t catecholamine surge → fluid needs to be secreted so air can fill lungs

• mechanical expulsion of fluid

• ↓ fetal respiratory movements, O2, pH, bicarb (acidotic)

  • during contractions → placenta blood flow decreases → less O2 & builds up CO2 → fetal respiratory movement slows down to conserve energy

• ↑ PCO2

  • not removing CO2 waste

what are the 4 stages of labor?

1. first

• true labor to complete cervical dilation to 10 cm

• longest of all stages

• 2 phases: latent & active

2. second

• cervix 10 cm dilated to birth to baby

• contractions occur every 2-3 mins, lasting for 1 min → strong by palpation

• pushing stage

3. third

• birth of infant to placental separation (starts after newborn is born & ends w/ separation & birth of placenta)

  • placental separation & expulsion (continued contractions will cause placenta to come out)

    • placenta detaches from wall & exits through vagina

• if newborn is stable enough, bonding happens at this stage! → baby is skin to skin contact on abd or chest

4. fourth

• 1 to 4 hours following delivery, recovery stage

what is latent vs active phase?

1. latent

• 0-6 cm dilation, 0 to 40% effacement

• starts w/ regular contractions & ends when rapid cervical dilation begins

• contractions occur every 5 to10 mins, lasts 30 to 45 seconds

• contraction intensity is mild to palpate

• many people remain talkative & contractions are similar to menstrual cramps

2. active

• 6 to 10 cm dilation, 40% to 100% effacement

• contractions occurs every 2-5 mins, lasts 45 to 60 secs

• contraction intensity is moderate to palpate → discomforting

• pt is more inwardly focused (concentrated on birth), limited interactions with others in the room

what factors influence pain during childbirth?

physiologic, spiritual, psychosocial, cultural, environmental

what is the difference between spontaneous vs directed pushing? when do these ways occur?

• these ways occur in the 2nd stage of labor

• spontaneous

  • following the birthing parent’s spontaneous urge

  • a more natural way of managing 2nd stage of labor

• directed pushing

  • pushing directed by caregiver