STUDY GUIDE
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
Increased energy level (nesting)
Bloody show
Braxton Hicks contractions
Spontaneous rupture of membranes
True vs. False Labor
Contraction timing
Contraction strength
Contraction discomfort
Change in contraction activity
Stay or go? (see Table 13.1)
Critical Factors Affecting Labor and Birth (5 P’s)
Passageway (birth canal: pelvis and soft tissues)
Passenger (fetus and placenta)
Powers (contractions)
Position (maternal)
Psychological response
Additional Factors Affecting Labor and Birth
Philosophy (low tech, high touch)
Partners (support caregivers)
Patience (natural timing)
Patient preparation (childbirth knowledge base)
Pain control (comfort measures)
Labor
Softening of cervix
Lightening
Mucous plug
Dilation= 0-10 cm
,Effacement- 0-100%
Primp- 1st pregnancy
Multip- multiple pregnancies
False labor- irregular timing, stop with rest
True labor= cervical change, felt in the back and around abdomen,
effacement
CHAPTER 13
5 p’s-
PASSAGWAY- widened pelvis , gynoid pelvis, bony pelvis, False pelvis,
cervix, vaginal vault
True pelvis: is the bony passageway through which the fetus
must travel.
made up of three planes: the inlet, the mid-pelvis (cavity), and the
outlet.
PELVIC INLET- defines the lower margin of the true pelvis and is
bound by the ischial tuberosities, the lower rim of the symphysis pubis,
and the tip of the coccyx.
Mid Pelvis- As the fetus passes through this small area, their chest is
compressed, causing lung fluid and mucus to be expelled alows them
to take their first breath
PELVIC OUTLET- must be large enough, is measured by the Diagonal
conjugate
PASSENGER- The fetus (with placenta) is the passenger. Skull: anterior
and posterior, diamond shaped, attitude; is the head down or up, LOA, ROA,
ROP, LOP, LIE – LONGINTUDINAL/TRANSVERSE: presentation: Cephalic,
breach, transverse, frank breach, position, station, engagement: extension
and flexion, go up in numbers, zero station, ischial spines
Fetal Head
o Bones in head are not fused, and have gaps in between
o Majority of injuries to the skull during childbirth are self-limiting ,
temporary with full recovery
o Sutures help assist in identifying position of fetal head during
delivery
, o The two most important diameters that can affect the birth
process are the suboccipitobregmatic (approximately 9.5 cm at
term) and the biparietal (approximately 9.25 cm at term)
diameters.
o Optimal head position: Babys chin should rest on chest with face
down
Fetal Attitude
o The most common fetal attitude when labor begins is with all
joints flexed—the fetal back is rounded, the chin is on the
chest, the thighs are flexed on the abdomen, and the legs are
flexed at the knees
o When the fetus presents with abnormal attitude, (no flexion or
extension), this increases the diameter of head. Which
increases difficulty of birth
Fetal Lie
o There are three possible lies: longitudinal (the most common),
transverse, and oblique.
o A fetus in a transverse or oblique lie position cannot be
delivered vaginally
Fetal Presentation- refers to the body part of the fetus that enters
the pelvic inlet first (the “presenting part”)
o (95% to 96%) are born in a cephalic presentation
This presentation is also referred to as a vertex
presentation
o 3% to 4% are breech
Breech presentation occurs when the fetal buttocks or
feet enter the maternal pelvis first
the largest part of the fetus (skull) is born last and may
become stuck in the pelvis
Cord compression can occur as baby is coming out
Soft tissues of baby are not as effective for cervical
dilation
Finally, there is the possibility of trauma to the head as
a result of the lack of opportunity for molding.
Frank breech (50% to 70%)- the buttocks
present first with both legs extended up toward
the face. In a full or complete breech
o A frank breech can result in a vaginal birth
, full or complete breech (5% to 10%), the
fetus sits cross-legged above the cervix.
footling or incomplete breech (10% to 40%),
one or both legs are presenting.
o Breech presentations are associated with prematurity,
previous history of breech birth, placenta previa, multiparity,
contracted maternal pelvis, uterine abnormalities (fibroids),
extreme volumes of amniotic fluid, and some congenital
anomalies such as hydrocephaly
o 1% are shoulder presenting
A shoulder presentation occurs when the fetus is in a
transverse lie with the shoulder as the presenting part
Shoulder dystocia is a delivery complication where
the baby’s shoulders get stuck behind the mother’s
pelvic bone after the head is delivered, making it hard
for the rest of the body to come out. It’s an emergency
that needs quick action to help prevent injury to the
baby and mother.
Fetal Position- describes the relationship of a given point on the
presenting part of the fetus to a designated point of the maternal
pelvis
o O- occipital bone presenting
o M-mentum- chin presenting
o S- sacrum presenting
o A- acromion- shoulder presenting
o Fetal position is determined first by identifying the presenting
part and then the maternal quadrant the presenting part is
facing
o Position is indicated by a three-letter abbreviation as follows:
The first letter indicates if the presented part is facing R
or L
The second letter indicates the body part thats
presenting first ex: O for occipital
The third letter indicates location of the presenting part:
A anterior or P posterior or T transverse
LOA is currently the most common (and most favorable)
fetal position for birthing, followed by right occiput
anterior (ROA).
Fetal Station
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
Increased energy level (nesting)
Bloody show
Braxton Hicks contractions
Spontaneous rupture of membranes
True vs. False Labor
Contraction timing
Contraction strength
Contraction discomfort
Change in contraction activity
Stay or go? (see Table 13.1)
Critical Factors Affecting Labor and Birth (5 P’s)
Passageway (birth canal: pelvis and soft tissues)
Passenger (fetus and placenta)
Powers (contractions)
Position (maternal)
Psychological response
Additional Factors Affecting Labor and Birth
Philosophy (low tech, high touch)
Partners (support caregivers)
Patience (natural timing)
Patient preparation (childbirth knowledge base)
Pain control (comfort measures)
Labor
Softening of cervix
Lightening
Mucous plug
Dilation= 0-10 cm
,Effacement- 0-100%
Primp- 1st pregnancy
Multip- multiple pregnancies
False labor- irregular timing, stop with rest
True labor= cervical change, felt in the back and around abdomen,
effacement
CHAPTER 13
5 p’s-
PASSAGWAY- widened pelvis , gynoid pelvis, bony pelvis, False pelvis,
cervix, vaginal vault
True pelvis: is the bony passageway through which the fetus
must travel.
made up of three planes: the inlet, the mid-pelvis (cavity), and the
outlet.
PELVIC INLET- defines the lower margin of the true pelvis and is
bound by the ischial tuberosities, the lower rim of the symphysis pubis,
and the tip of the coccyx.
Mid Pelvis- As the fetus passes through this small area, their chest is
compressed, causing lung fluid and mucus to be expelled alows them
to take their first breath
PELVIC OUTLET- must be large enough, is measured by the Diagonal
conjugate
PASSENGER- The fetus (with placenta) is the passenger. Skull: anterior
and posterior, diamond shaped, attitude; is the head down or up, LOA, ROA,
ROP, LOP, LIE – LONGINTUDINAL/TRANSVERSE: presentation: Cephalic,
breach, transverse, frank breach, position, station, engagement: extension
and flexion, go up in numbers, zero station, ischial spines
Fetal Head
o Bones in head are not fused, and have gaps in between
o Majority of injuries to the skull during childbirth are self-limiting ,
temporary with full recovery
o Sutures help assist in identifying position of fetal head during
delivery
, o The two most important diameters that can affect the birth
process are the suboccipitobregmatic (approximately 9.5 cm at
term) and the biparietal (approximately 9.25 cm at term)
diameters.
o Optimal head position: Babys chin should rest on chest with face
down
Fetal Attitude
o The most common fetal attitude when labor begins is with all
joints flexed—the fetal back is rounded, the chin is on the
chest, the thighs are flexed on the abdomen, and the legs are
flexed at the knees
o When the fetus presents with abnormal attitude, (no flexion or
extension), this increases the diameter of head. Which
increases difficulty of birth
Fetal Lie
o There are three possible lies: longitudinal (the most common),
transverse, and oblique.
o A fetus in a transverse or oblique lie position cannot be
delivered vaginally
Fetal Presentation- refers to the body part of the fetus that enters
the pelvic inlet first (the “presenting part”)
o (95% to 96%) are born in a cephalic presentation
This presentation is also referred to as a vertex
presentation
o 3% to 4% are breech
Breech presentation occurs when the fetal buttocks or
feet enter the maternal pelvis first
the largest part of the fetus (skull) is born last and may
become stuck in the pelvis
Cord compression can occur as baby is coming out
Soft tissues of baby are not as effective for cervical
dilation
Finally, there is the possibility of trauma to the head as
a result of the lack of opportunity for molding.
Frank breech (50% to 70%)- the buttocks
present first with both legs extended up toward
the face. In a full or complete breech
o A frank breech can result in a vaginal birth
, full or complete breech (5% to 10%), the
fetus sits cross-legged above the cervix.
footling or incomplete breech (10% to 40%),
one or both legs are presenting.
o Breech presentations are associated with prematurity,
previous history of breech birth, placenta previa, multiparity,
contracted maternal pelvis, uterine abnormalities (fibroids),
extreme volumes of amniotic fluid, and some congenital
anomalies such as hydrocephaly
o 1% are shoulder presenting
A shoulder presentation occurs when the fetus is in a
transverse lie with the shoulder as the presenting part
Shoulder dystocia is a delivery complication where
the baby’s shoulders get stuck behind the mother’s
pelvic bone after the head is delivered, making it hard
for the rest of the body to come out. It’s an emergency
that needs quick action to help prevent injury to the
baby and mother.
Fetal Position- describes the relationship of a given point on the
presenting part of the fetus to a designated point of the maternal
pelvis
o O- occipital bone presenting
o M-mentum- chin presenting
o S- sacrum presenting
o A- acromion- shoulder presenting
o Fetal position is determined first by identifying the presenting
part and then the maternal quadrant the presenting part is
facing
o Position is indicated by a three-letter abbreviation as follows:
The first letter indicates if the presented part is facing R
or L
The second letter indicates the body part thats
presenting first ex: O for occipital
The third letter indicates location of the presenting part:
A anterior or P posterior or T transverse
LOA is currently the most common (and most favorable)
fetal position for birthing, followed by right occiput
anterior (ROA).
Fetal Station
