Chapter 12: Processes of Birth

Question 1

characteristics of contractions

Answer 1

• coordinated
• involuntary
• intermittent: to allow for blood flow in intervillous space, b/c during contraction, no blood flow to baby, and they only have a certain amount of reserve

Question 2

acme

Answer 2

peak of contraction–>where contraction is the strongest

Question 3

uterine activity during labor

Answer 3

• Uterine Activity during labor is characterized by opposing features.
  
  • Upper 2/3 actively contracts to push the fetus down.
  • The lower third of the uterus remains less active , promoting downward passage of the fetus.
  • The cervix is passive.
    
    • The net effect of labor contractions is enhanced because the downward push from the upper uterus is accompanied by reduced resistance to fetal descent in the lower uterus..
• Myometrial cells in the upper uterus remains shorter at the end of each contractions rather than returning to their original length; myometrial cells in the lower uterus become longer with each contraction.
  
  • These two characteristics enable the upper uterus to maintain tension between contractions to preserve the cervical changes and downward fetal progress made with each contraction.
• The opposing characteristics of myometrial contraction in the upper and lower uterine segments cause changes in the thickness of the wall during labor.
  
  • The upper uterus becomes thicker while the lower uterus becomes thinner and is pulled upward during labor.
• The physiologic retraction ring marks the division between the upper and lower segment of the uterus.
• Opposing characteristics of contractions in the upper and lower uterine segments change the shape of the uterine cavity, which becomes more elongated and narrow as labor progresses.
  
  • This change in uterine shape straightens the fetal body and efficiently directs it downward in the pelvis.

Question 4

cervical changes during labor

Answer 4

• effacement: thinning of the cervix
  
  • 0 to 100% OR 3.5 cm to 0 cm
• dilation: opening of the cervix
  
  • 0-10 cm

Question 5

difference in cervical changes during labor in nulliparous and multiparous women

Answer 5

• nullipara: has to efface before dilate
• multipara: starts to dilate, then gradually goes thru effacement

Question 6

Maternal CV Response to Labor

Answer 6

• blood flow to placenta dec during contractions
  
  • 300-500 mL of blood shunted from placenta to maternal system with contractions
    
    • SO, maternal HR dec and BP inc
    • therefore, take BP when uterus is relaxed
• Keep mom in LEFT lateral position and semi-Fowler’s
  
  • avoid supine!

Question 7

Maternal Respiratory Response to Labor

Answer 7

• rate and depth inc slightly b/c uterus pushing up on diaphragm
  
  • inc rate if pain and anxiety present
• hyperventilation–>respiratory alkalosis
  
  • S/S tingling hands and feet, numbness, dizziness

Question 8

Maternal GI Response to Labor

Answer 8

• gastric motility reduced
• thirst remains, but appetite reduced
• dry mouth
  
  • need to provide fluids–clear liquids (ice, popsicles, broth)
• n/v

Question 9

Maternal Urinary Response to Labor

Answer 9

• reduced sensation as labor progresses
  
  • potential problem: distended bladder
    
    • if epidural, often times don’t feel sensation to go
    • full bladder can slow labor and inc risk of injury
    • inhibits descent of fetus
    • encourage patient to void at least every 2 hours
  • intermittent or indwelling catheter may be used

Question 10

Maternal Hematopoietic Response to Labor

Answer 10

• assess blood loss after delivery
  
  • vaginal birth: 500 mL is normal
  • C-section: 1000 mL is normal
• during pregnancy, clotting factors and fibrinogen elevated
  
  • Hgb of 11 and HCT of 33 or higher gives adequate margin for safety
  • inc clotting and inc risk of thrombophlebitis PP–but helps prevent hemorrhage during delivery
• WBC elevated:
  
  • 14,000-16,000 normal during labor
  • early postpartum: can be upwards of 25,000

Question 11

Fetal Response in Labor: Placental Circulation

Answer 11

• placental circulation exchange takes place b/w contractions in the intervillous spaces
  
  • placenta has a reserve to fetus usually tolerates the intermittent interruption
  • reduced placental fcn with GDM and HTN so can put stress on fetus during contractions
• during labor:
  
  • blood supply dec during contractions and eventually stops temporarily
  • spiral As are compressed by uterine M on contraction
  • placental circulation has enough reserve compared w/ fetal basal needs to tolerate periodic interruption of blood flow

Question 12

Fetal Response in Labor: CV System

Answer 12

• indicator of fetal well-being
• average FHR: 110-160
• alterations in rate and rhythm: from normal labor effects or suggests fetal intolerance of stress of labor
• Preterm Infant: has a rate at the higher end of 110-160
  
  • this is b/c the PNS takes longer to develop (peaks at 28 weeks), so before that point, the fetal HR will be higher

Question 13

Fetal Response in Labor: Pulmonary System

Answer 13

• Fetal lungs
  
  • production of amniotic fluid allows for normal development
  • lung fluid must be cleared to allow normal breathing after birth
    
    • labor speeds up the absorption of lung fluid
    • some expelled with birth (thoracic squeeze–chest wall of infant compressed during labor then recoils when borm–>helps initiate breathing)
• catecholamines: epi and NE
  
  • produced by fetal adrenal glands in response to stress of labor

Question 14

What are the 4 factors affecting birth? (The “Critical Factors”)

Answer 14

• Powers
• Passage
• Passenger
• Psyche

Question 15

What are the three components of uterine contractions?

Answer 15

• Frequency: from beginning of one to the beginning of the next
• Duration: from beginning of one to the end
• Intensity: strength during peak or acme

Question 16

What are the “Powers?”

Answer 16

• they are the forces of labor:
  
  • contractions: during the 1st stage of labor–>onset to full dilation
    
    • contractions are the primary force that moves fetus
  • pushing (which utilize the abdominal muscles): during 2nd stage of labor–>full dilation to birth
    
    • contractions AND maternal pushing efforts help push fetus out

Question 17

What is the increment of a contraction?

What is the acme?

What is the decrement?

Answer 17

• increment: period of inc strength
  
  • occurs as contraction begins in fundus
• acme: peak
  
  • strongest point
• decrement: period of dec strength/intensity

Question 18

What are components of the “Passage?”

Answer 18

• size of pelvis
• type of pelvis
• ability to efface and dilate

Question 19

What are components that dictate the size of the pelvis?

Answer 19

• inlet: upper border of the true pelvis
• mid-pelvis: pelvic cavity
• outlet: lower border of the true pelvis
  
  • pubic arch to ischial tuberosities

Question 20

What are the 4 types of pelvis? describe them?

Answer 20

• gynecoid
• android
• platypelloid
• anthropoid

Question 21

what is the weight of the average baby born in the US?

Answer 21

• 7.5 pounds (3.5 kg)
  
  • range b/w 5.5-10 lbs

Question 22

What are the 3 components of the “Passenger?”

Answer 22

• fetus
• membranes
• placenta
  
  • presentation
  • fetal lie
  • attitude
  • position

Question 23

what is fetal lie?

What are the different types?

Answer 23

• fetal lie: orientation of the long axis of the fetus to the long axis of the woman
  
  • longitudinal: majority of cases
    
    • head or buttocks of fetus enters pelvis 1st
  • transverse: long axis of fetus is at right angle to woman’s long axis
    
    • almost always have to have a cesarean section
  • oblique: lie b/w longitudinal and transverse

Question 24

which fetal head diameter is ideal, and how long is it?

Answer 24

• ideally, head would be fully flexed and the AP diameter would be submentobregmatic which is 9.5 cm

Question 25

what does presentation of the fetus mean?

What is the ideal presentation and why?

Answer 25

• presentation: fetal part that enters the pelvis first
  
  • can be cephalic, breech, or vertex
    
    • ideally, cephalic presentation w/ head flexed
      
      • most favorable b/c fetal head is largest part, fetal head can mold to pelvis, and the head is smooth, round, and hard

Question 26

what are the 4 variations of cephalic presentation?

Answer 26

• vertex presentation
• military presenation
• brow preseantation
• face presentation

Question 27

Vertex Presentation

Answer 27

• type of cephalic presenation
• most common
• fetal head is fully flexed
• allows for smallest suboccipitobregmatic diameter

Question 28

Military Presentation

Answer 28

• type of cephalic presenation
• head in neutral position
• longer occipitofrontal diameter presenting

Question 29

Brow Presentation

Answer 29

• type of cephalic presentation
• fetal head is partly extended
• unstable
• longest supraoccipitomental diameter presenting

Question 30

Face Presentation

Answer 30

• type of cephalic presentation
• head is in full extension
• fetal occiput in near fetal spine
• submentobregmatic diameter presenting

Question 31

Molding

Answer 31

• sutures and fontanels allow for this
  
  • it is shaping of the fetal head thru the birth canal

Question 32

What is normal molding?

Answer 32

• Caput should be central

Question 33

What is fetal attitude?

What is normal?

Answer 33

• it is relation of the fetal body parts to one another
• normal: flexion–>head is flexed toward the chest and arms and legs flexed over thorax
  
  • back curved in a C shape

Question 34

what is breech presentation?

when is breech presentation most common?

what are the variations in breech presentation?

Answer 34

• breech: fetal buttocks near pelvis first
• more common w/:
  
  • preterm births
  • births with hydrocephalus
  • births with placenta previa
• 3 variations:
  
  • Frank breech
  • full (complete) breech
  • footling breech

Question 35

describe a Frank breech

Answer 35

• fetal legs extended across abdomen toward shoulders

Question 36

describe a full (complete) breech

Answer 36

• reversal of normal cephalic
• head, knees, and hips flexed, but buttocks is presenting

Question 37

when is a shoulder presentation most common?

Answer 37

• preterm
• high parity
• PROM
• hydramnios
• placenta previa
  
  • MUST have a CS

Question 38

Explain the position of the passenger

Answer 38

• relationship of a fixed landmark on presenting part to front/back and side (L/R) of the maternal pelvis
  
  • 3 parts to description:
    
    • presenting part: occiput (vertex position), mentum (face presentation), or sacrum (breech presentation)
    • maternal side: anterior or posterior or transverse
    • maternal side: left or right
  • designate by 3 letter: L O A

Question 39

what is fetal station?

Answer 39

• measurement of descent of the fetal presenting part in relation to the ischial spines on the maternal pelvis
  
  • Ischial spines is a zero station
  • Numbers above are negative
  • Numbers below are positive
    
    • Fetus should move from a -5, -4, -3, -2, -1, 0, +1, +2, +3, +4, +5
      
      • -5 to +5

Question 40

What are the components of “Psyche?”

Answer 40

• anxiety: catecholamines inhibit contractions and placental blood flow
• fear
  
  • relaxation augments natural process of labor
• culture and expectations
• relationship with partner
• family presence
• past experience
• present pregnant experience
• safety
• education
• technology: maintain focus on mother not technology

Question 41

when will the baby be born?

Answer 41

• term gestation between 38-42 weeks
  
  • go full 40 weeks if possible, even though elective inductions often at 39 weeks

Question 42

What are the factors that appear to have a role in starting labor?

Answer 42

• changes in ratio of maternal estrogen to progesterone so that estrogen is higher than progesterone
  
  • Progesterone keeps uterine muscles relaxed
  • As estrogen rises, it makes the uterus more sensitive to PGs and oxytocin and cause and inc in the number of gap junctions
• PGs secreted by fetal membrane
• inc secretion of oxytocin maintains labor and oxytocin receptors on the uterus inc
• likely fetal role in secreting cortisol
• mechanical factors: stretching, pressure, and irritation
  
  • feedback loop: fetal head stretches cervix and causes release of oxytocin–>fundus of uterus contracts–>pushes fetal head against cervix–>more fundal contractions
• protein produced when fetal lungs mature

Question 43

what are the premonitory signs of labor?

Answer 43

• Braxton Hicks (irregular, mild uterine contractions)
• Lightening (descent of fetus towards pelvis inlet 2-3 wks before labor)
  
  • may notice easier breathing, inc pressure on bladder, leg cramps and edema
• ROM
• cervical ripening (cervix softens)
• bloody show (effacement and dilation cause expulsion of mucus plug and rupture small cervical capillaries which lead to bloody show)
• sudden burst of energy (nesting)
• loss of 1-3 lbs (excretion of fluid r/t altered estrogen progesterone ratio)

Question 44

Compare True Labor and False Labor

Answer 44

• True Labor:
  
  • begins in back and radiates to abdomen
  • intensity inc with walking
  • inc duration, intensity, frequency of contractions
  • progressive effacement and dilation
  • regular intervals b/w contractions
• False Labor:
  
  • discomfort in abdomen nad groin
  • walking has no effect or may dec
  • inconsistent in freq, duration, intensity
  • no effacement, dilation, descent
  • irregular contractions

Question 45

First Stage of Labor

Answer 45

• cervical effacement and dilation occur
• longest stage
• Begins with the onset of true labor contractions and ends with complete dilation (10 cm) and 100% effacement
• rate:
  • nullipara: dilate 1.2 cm/hour
  • multipara: dilate 1.5 cm/hour

Question 46

Phases of the First Stage of Labor

Answer 46

• Latent Phase
• Active Phase
• Transition Phase

Question 47

Latent Phase of Labor

Answer 47

• lasts thru first 3 cm of dilation
• longer for nullipara (7-8 hours) than multipara (4-5 hours)
• contractions gradually inc in freq, duration, intensity
  
  • interval b/w contractions should shorten to 5 min as progress to active labor
  • duration inc to 30-40 sec
• back discomfort which encircles the lower abdomen with each contraction
• behavior: sociable, excited, cooperative, anxious

Question 48

Active Phase of Labor

Answer 48

• cervix dilates from 4 to 7 cm more quickly than latent phase
• effacement complete
• fetus descends and internal rotation begins
• slightly longer if epidural
• contractions: 2-5 min apart and 40-60 sec long
• discomfort inc
• behavior: anxious, feel helpless, serious inward focus

Question 49

Transition Phase of Labor

Answer 49

• dilate from 8-10 cm and fetus descends further
• bloody show often inc with complete dilation
• short but intense phase
• contractions: 1.5-2 min apart, 60-90 sec
• leg tremors, n/v, and urge to push
• behavior: irritability, loss of control

Question 50

Second Stage of Labor

Answer 50

• Begins with complete dilation and full effacement and ends with the birth
• Varies depending on if a woman had an epidural (nulliparous: no epidural=53-57 min; w/ epidural=79 min; multiparous: no epidural=17-19 min; w/ epidural=45 min)
• Contractions: 2-3 min apart, 40-60 long
• as the fetus descends, it places pressure on the rectum and pelvic floor that causes an involuntary pushing response in the mother
• woman regains a feeling of control and feels tremendous relief and excitement with the birth

Question 51

Third Stage of Labor

Answer 51

• Begins with birth of baby and ends with expulsion of placenta
• Shortest: lasts about 6 min
• When the infant is born, the uterine cavity becomes much smaller
  
  • This causes the placenta to separate from uterine wall which is obvious by 4 signs:
    
    • Uterus is spherical
    • Uterus rises upward in abdomen as placenta descends
    • Cord descends further from vagina
    • Gush of blood
• Uterus must contract and remain contracted to compress open vessels and prevent hemorrhage

Question 52

Fourth Stage of Labor

Answer 52

• From placental delivery thru first 1-4 hours after birth
• Should be able to palpate uterus as a firm, rounded mass about 10-15 cm
  
  • If feels boggy and increasing in size, then may be assoc with postpartum hemorrhage
• Lochia: vaginal drainage after childbirth
• Most women feel chilled after childbirth most likely r/t sudden dec in effort, loss of heat produced by the fetus, dec in intraabdominal pressure, fetal blood cells entering maternal circulation
• Discomfort caused by birth trauma or afterpains
• Behavior: excited, tired
• Ideal time for bonding and best time to initiate breastfeeding

Question 53

What are afterpains?

Answer 53

• Afterpains are intermittent contractions that occur after birth as the uterus begins to return to prepregnancy state—more common if multiparous, women who breastfeed, women who have large babies

Question 54

What are the cardinal movements?

Answer 54

• descent: fetal presenting part moves into true pelvis
• engagement: when the largest diameter of the fetal presenting part has passed the pelvic inlet and entered the pelvic cavity
  
  • Usually occurs when the station of the presenting part is 0 or lower
• flexion
• internal rotation: occiput rotates so sagittal suture is AP pelvic diameter
• extension
  
  • _​_extension of head under symphysis
• external rotation
  
  • _​_head turns back to side
  • shoulders rotate to AP position
• expulsion
  
  • _​_occurs first as anterior, then posterior, shoulder passes under symphysis

Question 55

what is the most important intervention for AROM?

Answer 55

• listen to FHR–>may indicate a prolapsed cord!