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OB EXAM 2 STUDY GUIDE
CH 13 - Labor and Birth Process
SUSSET H. ALCOVER
Factors Influencing the Onset of Labor
• Uterine stretch
• Progesterone withdrawal
• Increased oxytocin sensitivity
• Increased release of prostaglandins
Premonitory Signs of Labor
• Cervical changes (cervical softening, possible cervical dilation)
• Lightening: when the fetal presenting parts begin to descend into the
true pelvis§ Breathing becomes easier, decrease gastric reflux
§ Increase pelvic pressure, leg cramping, dependent edema, low
back pain§ Primiparas may feel it two weeks in advance
• Increased energy level (nesting)– there is an increase in energy 24-48 hrs. before d/t
increase epinephrine– women begin to prepare for labor
• Bloody show
• Braxton Hicks contractions
§ Not true contractions until cervical dilation
occurs§ BHC last about 30 seconds
§ If last more than 30 seconds and more than 4-6 /hr.à contact HCP, especially if
< 37 weeksàpossible premature labor
• Spontaneous rupture of
membranes§ Increase risk for
infection
§ Risk for cord prolapse if engagement has not occurred
True Versus False Labor
• Contraction timing
• Contraction strength
• Contraction discomfort
• Change in contraction activity
• Stay home or go to the hospital?
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OB EXAM 2 STUDY GUIDE SUSSET H. ALCOVER
Critical Factors Affecting Labor and Birth (“Five Ps”)
• Passageway (birth canal: pelvis and soft tissues)
• Passenger (fetus and placenta)
• Powers (contractions)
• Position (position of the fetus in relation to the maternal)
• Psychological response
Five Additional Factors Affecting the Labor Process
• Philosophy (low tech, high touch)
• Partners (support caregivers)
• Patience (natural timing)
• Patient preparation (childbirth knowledge base)
§ Learning about labor and birth allows women and couples to express their needs and
preferences, enhance their confidence and improve communication between
themselves and the staff
• Pain control (comfort measures)
§ Pain during labor is a universal experience
§ The goal is to control the discomforts w/o harming the fetus or labor process
§ The challenge for care providers is to find the right combination of pain/coping
management methods to keep the discomfort manageable while minimizing the
negative effects on the fetus, the normal physiology of labor, maternal-infant bonding,
and a woman’s perception of labor itself
Passageway: Bony Pelvis
• Linea terminalis: division of false and true pelvis
• True pelvis (below linea
terminalis)§ Inlet
§ Midpelvis
§ Outlet (pelvic measurements)
• False pelvis (above linea terminalis)
§ Upper flared parts of two iliac bones
and concavities
§ Wings of base of sacrum
• Pelvic shape– pelvic measurement occurs in
the first trimester
§ Gynecoid: favorable for vaginal delivery.
Allows early and complete fetal rotation
during labor.
§ Android: male shaped, not
favorable§ Anthropoid: usually
adequate
§ Platypelloid: not favorable
Passageway: Soft Tissues
• Cervix
§ Thins through effacement to allow presenting part to descend into vagina
• Pelvic floor muscles
1
OB EXAM 2 STUDY GUIDE
CH 13 - Labor and Birth Process
SUSSET H. ALCOVER
Factors Influencing the Onset of Labor
• Uterine stretch
• Progesterone withdrawal
• Increased oxytocin sensitivity
• Increased release of prostaglandins
Premonitory Signs of Labor
• Cervical changes (cervical softening, possible cervical dilation)
• Lightening: when the fetal presenting parts begin to descend into the
true pelvis§ Breathing becomes easier, decrease gastric reflux
§ Increase pelvic pressure, leg cramping, dependent edema, low
back pain§ Primiparas may feel it two weeks in advance
• Increased energy level (nesting)– there is an increase in energy 24-48 hrs. before d/t
increase epinephrine– women begin to prepare for labor
• Bloody show
• Braxton Hicks contractions
§ Not true contractions until cervical dilation
occurs§ BHC last about 30 seconds
§ If last more than 30 seconds and more than 4-6 /hr.à contact HCP, especially if
< 37 weeksàpossible premature labor
• Spontaneous rupture of
membranes§ Increase risk for
infection
§ Risk for cord prolapse if engagement has not occurred
True Versus False Labor
• Contraction timing
• Contraction strength
• Contraction discomfort
• Change in contraction activity
• Stay home or go to the hospital?
,2
, 3
2
OB EXAM 2 STUDY GUIDE SUSSET H. ALCOVER
Critical Factors Affecting Labor and Birth (“Five Ps”)
• Passageway (birth canal: pelvis and soft tissues)
• Passenger (fetus and placenta)
• Powers (contractions)
• Position (position of the fetus in relation to the maternal)
• Psychological response
Five Additional Factors Affecting the Labor Process
• Philosophy (low tech, high touch)
• Partners (support caregivers)
• Patience (natural timing)
• Patient preparation (childbirth knowledge base)
§ Learning about labor and birth allows women and couples to express their needs and
preferences, enhance their confidence and improve communication between
themselves and the staff
• Pain control (comfort measures)
§ Pain during labor is a universal experience
§ The goal is to control the discomforts w/o harming the fetus or labor process
§ The challenge for care providers is to find the right combination of pain/coping
management methods to keep the discomfort manageable while minimizing the
negative effects on the fetus, the normal physiology of labor, maternal-infant bonding,
and a woman’s perception of labor itself
Passageway: Bony Pelvis
• Linea terminalis: division of false and true pelvis
• True pelvis (below linea
terminalis)§ Inlet
§ Midpelvis
§ Outlet (pelvic measurements)
• False pelvis (above linea terminalis)
§ Upper flared parts of two iliac bones
and concavities
§ Wings of base of sacrum
• Pelvic shape– pelvic measurement occurs in
the first trimester
§ Gynecoid: favorable for vaginal delivery.
Allows early and complete fetal rotation
during labor.
§ Android: male shaped, not
favorable§ Anthropoid: usually
adequate
§ Platypelloid: not favorable
Passageway: Soft Tissues
• Cervix
§ Thins through effacement to allow presenting part to descend into vagina
• Pelvic floor muscles
