MATERNAL HEALTH: LABOR + DELIVERY (I)
(7) The Process of Labor and Birth
THE ONSET OF LABOR
Occurs — 38-42 weeks
Beginning of Pregnancy :
● Uterus = Relaxed / / Cervix = Closed + Firm (maintain pregnancy)
End of Pregnancy :
● Uterus = More excitable // Cervix = Softened (Ripening)
Why does the CERVIX change?
● Breakdown of collagen fibers → Decrease in binding capacity
● Increase in cervical water content → Weakening + Softening
THE PROCESS OF LABOR + BIRTH
Critical Factors that bring about childbirth: “Ps” of Labor
1) Powers(physiological factors)
2) Passageway (maternal pelvis)
3) Passenger (fetus + placenta)
4) Passageway + Passenger Relationship (engagement, station, position)
5) Psychosocial Influences (previous experiences, emotional status)
POWERS (Physiological Factors) (involuntary/voluntary)
● Uterine Contractions = 1° PRIMARY POWERS (involuntary)
○ Signal beginning of labor
○ Cause cervical Dilation + Effacement
○ Move fetus down → Birth canal (1st stage of labor)
■ Dilation: Opening + Enlargement of Cervix (0-10cm)
■ Effacement: Shortening + Thinning of Cervix (0-100%)
■ DO NOT PUSH if cervix is not fully dilated *
● Maternal pushing efforts = 2° SECONDARY POWERS (voluntary)
○ Urge to bear down
○ Once cervix = FULLY dilated (10cm)
,Characteristics of Uterine Contractions (1° PRIMARY POWERS)
Contractions: Rhythmic tightening of UTERUS; occur intermittently
● Purpose → Facilitate with Dilation + Effacement
● Inhibit blood flow to the placenta + fetus
1. Increment : Beginning of contraction; rise in intensity ⭧
2. Acme: Peak of contraction ⧊
3. Decrement: Decrease in contraction ↓
4. Relaxation: Time between contractions when the UTERUS = fully relaxed
a. Allows for fetal oxygenation
b. Blood flow = restored from the uterus → placenta
c. Helps avoid exhaustion
What happens to the UTERUS when it is being contracted?
● Upper portion = Thickens + Becomes more active
● Lower portion = Thinwalled + Passive
● “Physiological Retraction Ring”: ridged boundary between upper/lower
uterine segments
● Elongation with each contraction → Straightens fetal body
○ Upper body = Pressed against fundus
○ Lower = Pushed toward cervix
● Fetal Axis Pressure: Pressure exerted by fetus
○ This force + hydrostatic pressure of fetal membranes → Cervical dilation
Assessment of Uterine Contractions (1° PRIMARY POWERS)
1. Frequency: BEGINNING of 1 contraction → BEGINNING of next contraction
2. Duration: START of one contraction → END of SAME contraction
3. Intensity: Uterine palpation (Mild, Moderate, Strong)
,Palpation: Noninvasive; Fingertips → FUNDUS; gentle/no movement
1. Nose (Mild Intensity) → Soft at Acme
2. Chin (Moderate Intensity) → Firm FUNDUS = difficult to indent
3. Forehead (Strong intensity) → Inability to indent FUNDUS @ Acme
*CONTRACTION INTENSITY IS BEST ASSESSED WITH PALPATION*
Tocodynamometer : Noninvasive; External pressure-sensitive device applied against
uterine FUNDUS; recorded on graph paper
● Provides information on FREQUENCY + DURATION
● May not give accurate information on intensity
Intrauterine Pressure Catheter (IUPC): Invasive
● Inserted → CERVIX → UTERUS
● Measures INTENSITY + DURATION of contractions
● CAN ONLY BE USED IF AMNIOTIC MEMBRANES = RUPTURED
○ Must rupture membranes artificially if they have not spontaneously
ruptured
● Used with HIGH-RISK pregnancies
● RISK FOR INFECTION
INTENSITY Scale
● NORMAL Resting pressure (resting tone) = 10-12 mmHg
● ACME contraction↴
○ 25-40 mmHg (Early labor)
○ 50-70 mmHg (Active labor)
○ 70-90 mmHg (Transition)
○ 70-100 mmHg (Maternal Pushing: Second Stage)
Maternal Pushing Efforts 2° SECONDARY POWERS
● CERVIX = MUST BE FULLY DILATED (10cm)
● “Bearing Down” sensation
● Assists with expulsion of fetus; Use of abdominal muscles
● Complication: Bearing down on partial dilation → cervical edema/damage
,PASSAGEWAY (Maternal Pelvis)
● Maternal Pelvis
● Soft Tissues
Sections:
1. Inlet
2. Midpelvis (Pelvic Cavity)
3. Outlet
Types:
1. Gynecoid: Typical traditional; GOOD FOR CHILDBIRTH; largest measurements
2. Android: Resembles MALE pelvis; Triangular/Heart shaped; NARROW
3. Anthropoid: Oval-shaped; POSTERIOR FETAL DESCENT (Face facing front)
4. Platypelloid: PERRY needs a C-Section; FLAT; Transverse presentation
PASSENGER (Fetus + Placenta)
● Fetus
● Fetal Membranes
● Head-first (Optimal Position)
The Fetal Skull
● Face, Base of Skull, Vault of Cranium (roof)
● Molding: Overlapping/Overriding of cranial bones to move through → PELVIS
● Fontanelles: Two membrane-filled spaces where suture lines meet
○ Used during vaginal exams to determine → POSITION of fetus
○ Anterior Fontanelle: Larger; Diamond-shaped; Front of head; Stays
open until 18 months
○ Posterior Fontanelle: Smaller; Triangular; Back of head; Closes around
6-8 Weeks
,Fetal Lie
● The alignment of the fetus within the womb (Longitudinal Axis: Mother→Fetus)
○ Longitudinal: Spine parallel to mothers; Breech/Cephalic (99%)
○ Transverse: 90° angle/perpendicular; horizontal lie (<1%) C-SECTION
○ Oblique: Diagonal; room to move into transverse or longitudinal
Fetal Attitude
● Posture of the fetus inside the womb; relationship of fetus’s body parts
● “Fetal Position”
● NORMAL (Preferred): Attitude of FLEXION
○ Fetal head = Flexed
○ Chin touches chest
○ Arms = Flexed + Folded across chest
○ Thighs = Flexed on abdomen
○ Calves = Flexed against thighs
● Military Position does not interfere with labor
● Other positions with a larger anteroposterior diameter → longer/difficult labor
, Fetal Presentation
● Fetal part that enters → pelvic inlet FIRST → birth canal during labor
● “Presenting Part”: Part of fetal body first felt during vaginal exam
1. Cephalic (Head-First)
a. Vertex : FULLY flexed (Optimal)
b. Military: Neutral
c. Brow: Partial extension/Unstable
d. Face: FULLY extended
Advantages of Cephalic Presentation:
● Fetal head = LARGEST part of infant → once head is through, body will follow
● Fetal head = capable of molding → helps fetus move through the birth canal
● Fetal head = smooth + round → aids in cervical dilation
2. Breech (Booty-First)
● Associated with preterm birth/hydrocephaly/abnormal uterus/pelvis
● C-Section is usually warranted
a. Frank: Fetal legs = completely extended → shoulders
b. Complete (Full): Reversal of common cephalic position
c. Footling: One or Both legs are extended (Feet-First)
Disadvantages of Breech Presentation:
● RISK for umbilical cord prolapse
● Less effective in dilating cervix
● Umbilical cord compression
○ DELIVERY MUST BE RAPID TO PREVENT HYPOXIA *
(7) The Process of Labor and Birth
THE ONSET OF LABOR
Occurs — 38-42 weeks
Beginning of Pregnancy :
● Uterus = Relaxed / / Cervix = Closed + Firm (maintain pregnancy)
End of Pregnancy :
● Uterus = More excitable // Cervix = Softened (Ripening)
Why does the CERVIX change?
● Breakdown of collagen fibers → Decrease in binding capacity
● Increase in cervical water content → Weakening + Softening
THE PROCESS OF LABOR + BIRTH
Critical Factors that bring about childbirth: “Ps” of Labor
1) Powers(physiological factors)
2) Passageway (maternal pelvis)
3) Passenger (fetus + placenta)
4) Passageway + Passenger Relationship (engagement, station, position)
5) Psychosocial Influences (previous experiences, emotional status)
POWERS (Physiological Factors) (involuntary/voluntary)
● Uterine Contractions = 1° PRIMARY POWERS (involuntary)
○ Signal beginning of labor
○ Cause cervical Dilation + Effacement
○ Move fetus down → Birth canal (1st stage of labor)
■ Dilation: Opening + Enlargement of Cervix (0-10cm)
■ Effacement: Shortening + Thinning of Cervix (0-100%)
■ DO NOT PUSH if cervix is not fully dilated *
● Maternal pushing efforts = 2° SECONDARY POWERS (voluntary)
○ Urge to bear down
○ Once cervix = FULLY dilated (10cm)
,Characteristics of Uterine Contractions (1° PRIMARY POWERS)
Contractions: Rhythmic tightening of UTERUS; occur intermittently
● Purpose → Facilitate with Dilation + Effacement
● Inhibit blood flow to the placenta + fetus
1. Increment : Beginning of contraction; rise in intensity ⭧
2. Acme: Peak of contraction ⧊
3. Decrement: Decrease in contraction ↓
4. Relaxation: Time between contractions when the UTERUS = fully relaxed
a. Allows for fetal oxygenation
b. Blood flow = restored from the uterus → placenta
c. Helps avoid exhaustion
What happens to the UTERUS when it is being contracted?
● Upper portion = Thickens + Becomes more active
● Lower portion = Thinwalled + Passive
● “Physiological Retraction Ring”: ridged boundary between upper/lower
uterine segments
● Elongation with each contraction → Straightens fetal body
○ Upper body = Pressed against fundus
○ Lower = Pushed toward cervix
● Fetal Axis Pressure: Pressure exerted by fetus
○ This force + hydrostatic pressure of fetal membranes → Cervical dilation
Assessment of Uterine Contractions (1° PRIMARY POWERS)
1. Frequency: BEGINNING of 1 contraction → BEGINNING of next contraction
2. Duration: START of one contraction → END of SAME contraction
3. Intensity: Uterine palpation (Mild, Moderate, Strong)
,Palpation: Noninvasive; Fingertips → FUNDUS; gentle/no movement
1. Nose (Mild Intensity) → Soft at Acme
2. Chin (Moderate Intensity) → Firm FUNDUS = difficult to indent
3. Forehead (Strong intensity) → Inability to indent FUNDUS @ Acme
*CONTRACTION INTENSITY IS BEST ASSESSED WITH PALPATION*
Tocodynamometer : Noninvasive; External pressure-sensitive device applied against
uterine FUNDUS; recorded on graph paper
● Provides information on FREQUENCY + DURATION
● May not give accurate information on intensity
Intrauterine Pressure Catheter (IUPC): Invasive
● Inserted → CERVIX → UTERUS
● Measures INTENSITY + DURATION of contractions
● CAN ONLY BE USED IF AMNIOTIC MEMBRANES = RUPTURED
○ Must rupture membranes artificially if they have not spontaneously
ruptured
● Used with HIGH-RISK pregnancies
● RISK FOR INFECTION
INTENSITY Scale
● NORMAL Resting pressure (resting tone) = 10-12 mmHg
● ACME contraction↴
○ 25-40 mmHg (Early labor)
○ 50-70 mmHg (Active labor)
○ 70-90 mmHg (Transition)
○ 70-100 mmHg (Maternal Pushing: Second Stage)
Maternal Pushing Efforts 2° SECONDARY POWERS
● CERVIX = MUST BE FULLY DILATED (10cm)
● “Bearing Down” sensation
● Assists with expulsion of fetus; Use of abdominal muscles
● Complication: Bearing down on partial dilation → cervical edema/damage
,PASSAGEWAY (Maternal Pelvis)
● Maternal Pelvis
● Soft Tissues
Sections:
1. Inlet
2. Midpelvis (Pelvic Cavity)
3. Outlet
Types:
1. Gynecoid: Typical traditional; GOOD FOR CHILDBIRTH; largest measurements
2. Android: Resembles MALE pelvis; Triangular/Heart shaped; NARROW
3. Anthropoid: Oval-shaped; POSTERIOR FETAL DESCENT (Face facing front)
4. Platypelloid: PERRY needs a C-Section; FLAT; Transverse presentation
PASSENGER (Fetus + Placenta)
● Fetus
● Fetal Membranes
● Head-first (Optimal Position)
The Fetal Skull
● Face, Base of Skull, Vault of Cranium (roof)
● Molding: Overlapping/Overriding of cranial bones to move through → PELVIS
● Fontanelles: Two membrane-filled spaces where suture lines meet
○ Used during vaginal exams to determine → POSITION of fetus
○ Anterior Fontanelle: Larger; Diamond-shaped; Front of head; Stays
open until 18 months
○ Posterior Fontanelle: Smaller; Triangular; Back of head; Closes around
6-8 Weeks
,Fetal Lie
● The alignment of the fetus within the womb (Longitudinal Axis: Mother→Fetus)
○ Longitudinal: Spine parallel to mothers; Breech/Cephalic (99%)
○ Transverse: 90° angle/perpendicular; horizontal lie (<1%) C-SECTION
○ Oblique: Diagonal; room to move into transverse or longitudinal
Fetal Attitude
● Posture of the fetus inside the womb; relationship of fetus’s body parts
● “Fetal Position”
● NORMAL (Preferred): Attitude of FLEXION
○ Fetal head = Flexed
○ Chin touches chest
○ Arms = Flexed + Folded across chest
○ Thighs = Flexed on abdomen
○ Calves = Flexed against thighs
● Military Position does not interfere with labor
● Other positions with a larger anteroposterior diameter → longer/difficult labor
, Fetal Presentation
● Fetal part that enters → pelvic inlet FIRST → birth canal during labor
● “Presenting Part”: Part of fetal body first felt during vaginal exam
1. Cephalic (Head-First)
a. Vertex : FULLY flexed (Optimal)
b. Military: Neutral
c. Brow: Partial extension/Unstable
d. Face: FULLY extended
Advantages of Cephalic Presentation:
● Fetal head = LARGEST part of infant → once head is through, body will follow
● Fetal head = capable of molding → helps fetus move through the birth canal
● Fetal head = smooth + round → aids in cervical dilation
2. Breech (Booty-First)
● Associated with preterm birth/hydrocephaly/abnormal uterus/pelvis
● C-Section is usually warranted
a. Frank: Fetal legs = completely extended → shoulders
b. Complete (Full): Reversal of common cephalic position
c. Footling: One or Both legs are extended (Feet-First)
Disadvantages of Breech Presentation:
● RISK for umbilical cord prolapse
● Less effective in dilating cervix
● Umbilical cord compression
○ DELIVERY MUST BE RAPID TO PREVENT HYPOXIA *
