1. Chapter 8 The Labor Process

2. Four Essential Components of Labor
The Four Ps of Labor
Passageway
Passenger
Powers
Psyche
Problematic areas influence labor negatively

3. Passageway Consists of bony pelvis, soft tissues Bony pelvis
False pelvis
The flared upper portion of the bony pelvis
Not part of the bony passageway
True pelvis
The portion of the pelvis below the linea terminalis
Consists of the inlet, midpelvis, and outlet

4. Passageway (cont.) Pelvic shape Gynecoid
Most favorable for a vaginal birth
Rounded shape
Anthropoid
Elongated shape
Android
Heart-shaped

5. Passageway (cont.) Pelvic shape (cont.) Platypelloid
Flat in its dimensions
Pelvic dimensions
Most important is obstetric conjugate
Soft tissues
Cervix
Vagina

6. Question
State whether the following statement is true or false. The gynecoid pelvis is the most favorable for a vaginal birth.

7. Answer
True Rationale: The gynecoid pelvis is most favorable for a vaginal birth.

8. Passenger Fetal skull Most important in relation to labor and birth
Molding is overlap of bones
Fetal accommodation to the passageway
Fetal lie
Longitudinal lie: Long axis of the fetus is parallel to maternal long axis
Oblique lie: Between longitudinal and transverse lie

9. Passenger (cont.) Fetal lie (cont.) Transverse lie
Long axis of fetus is perpendicular to maternal long axis

10. Passenger (cont.) Fetal presentation
Foremost part of the fetus that enters the pelvic inlet
Three main presentations
Head: Cephalic presentation
Feet or buttocks: Breech presentation
Shoulder: Shoulder presentation

11. Passenger (cont.) Fetal attitude
Relationship of fetal parts to one another
Flexion (ovoid shape)
Most favorable for vaginal delivery
Military (no flexion or extension)
Brow or frontum (partial extension)
Face (full extension)

12. Passenger (cont.) Fetal position
Relationship of reference point on presenting part to quadrants of maternal pelvis
First letter/designation: Refers to side of maternal pelvis toward which presenting part is facing
Second letter/designation: Reference point on presenting part
Third letter/designation: Specifies direction presenting part is facing
Anterior; posterior; transverse

13. Passenger (cont.)
Fetal station: Relationship of presenting part to ischial spines
Zero station
Presenting part is at the level of the ischial spines
Minus station
Presenting part is above the ischial spines
Plus station
Presenting part is below the ischial spines

14. Powers Phases of involuntary uterine contraction Increment
Building up of the contraction – longest phase
Acme
Peak of the contraction
Decrement
Letting-up phase
Relaxation period
Rest period between contractions

15. Powers (cont.) Descriptors of contractions
Frequency: How often the contractions are occurring
Measured by counting time interval from beginning of one contraction to beginning of following contraction
Duration: Interval from beginning of a contraction to its end
Intensity: Strength of the contraction

16. Question
Fetal attitude refers to the relationship of fetal parts to each other. Which fetal attitude is most favorable to a vaginal birth? a. Extension b. Flexion c. Military d. Hyperextension

17. Answer
b. Flexion Rationale: The most common, most favorable attitude for a vaginal birth, is an attitude of flexion, also called a vertex presentation.

18. Psyche Factors impacting the psyche of a laboring woman
Current pregnancy experience
Previous birth experiences
Expectations for current birth experience
Preparation for birth
Presence and support of birth companion
Culture

19. Process of Labor Onset of labor Theories regarding labor onset
Progesterone withdrawal theory
Oxytocin theory
Prostaglandin theory
Maternal and fetal factors
Cascade effect

20. Process of Labor (cont.)
Anticipatory signs of labor
Lightening or sense that the baby has “dropped”
Increased frequency, intensity of Braxton Hicks contractions
Gastrointestinal disturbances
Expelling the mucus plug
Feeling a burst of energy
Clinical signs
Ripening (softening) and effacement (thinning) of the cervix

21. Process of Labor (cont.)
Differences between false and true labor
False (prodromal) labor
Increase in Braxton Hicks contractions without cervical changes
Can be uncomfortable
True labor
Progressive dilation and effacement of cervix

22. Mechanisms of a Spontaneous Vaginal Delivery
Cardinal movements (mechanisms of delivery)
Engagement
Descent
Flexion
Internal rotation
Extension
External rotation
Expulsion

23. Stages and Duration of Labor
First stage: Dilation
Early labor (latent phase)
Active labor (active phase)
Transition (transition phase)
Second stage: Birth
Third stage: Delivery of placenta
Fourth stage: Recovery

24. Question
Which stage of labor is birth? a. First stage b. Second stage c. Third stage d. Fourth stage

25. Answer
b. Second stage Rationale: The second stage begins when the cervix is dilated fully and ends with the birth of the infant.

26. Maternal and Fetal Adaptation to Labor
Maternal physiologic adaptation
Increased demand for oxygen during the first stage of labor
Increased heart rate
Increased cardiac output
Increased respiratory rate
Gastrointestinal and urinary systems are affected
Laboratory values impact

27. Maternal and Fetal Adaptation to Labor (cont.)
Maternal psychological adaptation
Early stage of labor – excited and talkative
Active labor
More introverted
Focusing energies on coping with stress of contractions
Transition: Feels out of control
Pushing phase: Feels more in control

28. Maternal and Fetal Adaptation to Labor (cont.)
Increase in intracranial pressure
Placental blood flow temporarily interrupted at peak of uterine contractions
Stresses cardiovascular system; results in slowly decreasing pH throughout labor
Passing through the birth canal is beneficial in two ways
Stimulates surfactant production; helps clear respiratory passageways

29. Maternal and Fetal Adaptation to Labor (cont.)
Ecchymosis
Edema
Caput succedaneum
Cephalohematoma