CHAPTER 6
COURSE AND CONDUCT OF LABOR AND DELIVERY
153
153
6
COURSE AND CONDUCT
OF LABOR AND DELIVERY
CHAPTER
Labor is the normal process of coordinated, effective involuntary
uterine contractions that lead to progressive cervical effacement
and dilatation and descent and delivery of the newborn and pla-
centa. Near its termination, labor may be augmented by voluntary
bearing-down efforts to assist in delivery of the conceptus.
False labor is characterized by irregular (both in interval and
duration), brief contractions without fundal dominance, cervical
change, or a lower station of the fetal vertex or breech.
Dilatation of the cervix is the diameter of the cervical os ex-
pressed in centimenters (0–10). Effacement is cervical thinning that
occurs before and especially during first stage labor. Effacement of
the cervix is expressed as a percentage of cervical length (normally
ϳ2.5 cm) (Figs. 6-1, 6-2). An uneffaced cervix is 0%; one about
0.25 in length is 100% effaced. Effacement and dilatation are caused
by retraction (takeup) of the cervix toward the uterine corpus, not
by pressure of the presenting part.
The initiation of labor in the human is poorly understood.
Labor can be triggered by one or more significant endocrine or
physical changes, for example, abdominal trauma. The onset of la-
bor can occur at any time after well-established pregnancy, but the
likelihood increases as term is approached. Labor can be induced
or stimulated (augmented) by oxytocic agents (e.g., oxytocin or
prostaglandin E

●
The powers (effective forces of labor, e.g., uterine contractions)
●
The placenta (an obstruction if implanted low in the
uterus)
FIGURE 6-1. Dilatation and effacement of the cervix in a primipara.
FIGURE 6-2. Dilatation and effacement of the cervix in a multipara.
FIGURE 6-3. Production of prostaglandins in human parturition.
(Modified after Liggins.) (From M.L. Pernoll and R.C. Benson, eds. Current Obstetric &
Gynecologic Diagnosis & Treatment, 6th ed. Lange, 1987.)
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Each of these factors, alone or in combination, can make for a
normal or a complicated labor and delivery. For example, if the fe-
tus is large and the pelvis is small, labor may be prolonged or
progress may be impossible despite strong contractions, even with
a placenta normally implanted in the fundus.
NORMAL LABOR
Since, hopefully, the end result of labor is the vaginal delivery of
the fetus, membranes, and placenta, the method of judging its
progress is based on assessments toward that end. The first stage
of labor begins with the onset of labor and ends with complete
FIGURE 6-4. Relationship between cervical dilatation and descent of the
presenting part in a primipara. L, latent phase; A, acceleration phase; M, phase
of maximum slope; D, deceleration phase; and 2, second stage.
(From M.L. Pernoll and R.C. Benson, eds. Current Obstetric & Gynecologic Diagnosis
& Treatment, 6th ed. Lange, 1987.)
(10 cm) dilatation of the cervix. The first stage is the longest,
averaging 8–12 h for primigravidas or 6–8 h for multiparas. How-

of the infant to 1 h after delivery of the placenta. The rapidity of
separation and means of recovery of the placenta determine the du-
ration of the third stage (Fig. 6-6).
MANAGEMENT OF THE FIRST STAGE
OF LABOR
INITIAL EXAMINATION
AND PROCEDURES
●
Obtain a history of relevant medical details following the
last examination.
FIGURE 6-6. Major types of deviation from normal progress of labor may
be detected by noting dilatation of the cervix at various intervals after labor
begins.
(From K.P. Russell. In: R.C. Benson, ed. Current Obstetric & Gynecologic Diagnosis &
Treatment, 4th ed. Lange, 1982.)
CHAPTER 6
COURSE AND CONDUCT OF LABOR AND DELIVERY
159
●
Record the patient’s vital signs (temperature, pulse, and BP).
Examine a clean-catch urine specimen for proteinuria and
glycosuria.
●
Do a brief general physical examination.
●
Palpate the uterus to determine the fetal presentation, position,
and engagement (Leopold’s maneuvers) (Fig. 6-7). Auscultate
the fetal heartbeat, and mark the skin where the heartbeat is
FIGURE 6-7. Leopold’s maneuvers. Determining fetal presentation (A and
B), position (C), and engagement (D).

Station zero is assumed by projection to be actual
engagement, that is, the biparietal diameter at the level
of the inlet. However, with considerable molding, caput
succedaneum, or a sincipital presentation of the head,
the biparietal diameter may be a significant distance
above the inlet even though the tip of the vertex is at the
spines without true engagement.
Dilatation of the cervix by direct palpation is expressed
as the diameter of the cervical opening in centimeters.
A diameter of 10 cm constitutes full dilatation.
Effacement of the cervix (process of thinning out) may
occur before labor in the nulligravida but is less likely
before the first stage of labor in the multigravida.
The position of the presenting part usually can be con-
firmed by internal examination.
Vertex presentations (Fig. 6-9). The fontanelles and the
sagittal suture are palpated. The position is determined
by the relation of the fetal occiput to the mother’s right
or left side. This is expressed as OA (occiput directly
anterior), LOA (left occiput anterior), LOP (left occiput
posterior), and so on.
Breech presentations are determined by the position of
the infant’s sacrum in relation to the mother’s right or
left side. This is expressed as SA (sacrum directly ante-
rior), LSA (left sacrum anterior), LSP (left sacrum pos-
terior), and so on.
Face presentation is caused by extension of the fetal
head on the neck. The chin, a prominent and identifiable
facial landmark, is used as the point of reference. As
with vertex presentations, the position of the fetal chin

comfort. However, keep the patient in bed after the membranes have
ruptured or until the presenting part has engaged to avoid cord pro-
lapse or compression.
Allow only clear liquids by mouth during labor to avoid dehy-
dration.
Analgesia should not be given until labor is definitely estab-
lished with the cervix Ͼ3 cm dilated. Analgesics and anesthesia
must be ordered on an individual basis, considering each patient’s
obstetric problems, the quality of labor, and her desire to be alert
or subdued.
FURTHER EXAMINATIONS
AND PROCEDURES
Electronic fetal monitoring (EFM) is simply one of the means of
assessing fetal status. It does have the advantage of being continu-
ous. The external type is innocuous, and the internal type carries
only slight risk. Although EFM is an excellent diagnostic tool, it is
not a substitute for correct clinical judgment. Current retrospective
and prospective data support the use of continuous internal EFM
for high-risk obstetric patients. Internal EFM is preferable to ex-
ternal EFM because it is more precise and comprehensive in ap-
praising fetal status. Nonetheless, electronic monitoring of low-risk
obstetric patients has not demonstrated a beneficial cost–benefit
ratio.
If continuous EFM is not used, auscultate and record the fetal
heart tones (FHT) for 1 min following a uterine contraction at least
every 30 min during the first stage, at least every 5 min during
the second stage, when the membranes rupture and again within
CHAPTER 6
COURSE AND CONDUCT OF LABOR AND DELIVERY
163

ery. The left lateral decubitus (Sims) or squatting position
may be used if a spontaneous uncomplicated birth is antic-
ipated. Another alternative is the squatting position.
●
The physician and assistants must carefully scrub their hands
and wear masks, eye protection, and sterile gloves. Any de-
livery may become surgically complicated.
●
Administer anesthesia if necessary (e.g., pudendal block).
●
Cleanse the pudendum with water and surgical detergent.
●
Drape the patient with sterile towels or sheets or both.
●
Sterile instruments and necessary supplies should be arranged
conveniently on a table or stand.
Generally
occurs in
late
pregnancy
or at onset
of labor.
Mode of
entry into
superior
strait
depends
on pelvic
configura-
tion

the ischial spines,
whereupon, when
the vertex reaches
the perineum,
rotation from a
posterior to an
anterior position
generally follows
Follows
distention
of the
perineum
by the
vertex.
Head
concomit-
antly stems
beneath the
symphysis.
Extension
is complete
with
delivery of
head
Following delivery,
head normally
rotates to the
position it originally
occupied at
engagement. Next,

generally
descends more
rapidly than
posterior at
both inlet and
outlet
Gradual descent
is the rule
Ordinarily takes place
when breech
reaches levator
musculature. Fetal
bitrochanteric
rotates to AP
diameter
Anterior shoulder
rotates so as to
bring shoulders into
AP diameter of
outlet
Occurs when
anterior hip
stems beneath
symphysis;
posterior hip
is born first
Anterior
shoulder at
symphysis,
and posterior

Occiput (if a
posterior) or face
(if an occiput
anterior) rotates to
hollow of sacrum;
this brings
presenting part to
AP diameter of
outlet
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●
Gloves (and gown) must be changed if contamination
occurs.
Delivery of the Head (Figs. 6-10 through 6-14)
●
During the late second stage, the head distends toward the
perineum and vulva with each uterine contraction, normally
aided by voluntary efforts of the mother. A patch of scalp
becomes visible. The presenting part recedes slightly during
the intervals of relaxation, but it crowns when its widest
FIGURE 6-10. Engagement of LOA.
FIGURE 6-11. LOA position.
FIGURE 6-12. Anterior rotation of head.
FIGURE 6-13. Extension of head.
FIGURE 6-14. External rotation of head.
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bulb or with a small catheter attached to a deLee-type suc-
tion trap.
●
Before external rotation (restitution), which occurs next, the
head usually is drawn back toward the perineum. This move-
ment precedes engagement of the shoulders, which are now
entering the pelvic inlet.
●
From this point on, support the infant manually and facili-
tate the mechanism of labor.
Do not hurry! If strong contractions wane, be patient—labor
will resume. Once the airway is clear, the infant can breathe and is
not in jeopardy.
Delivery of the Shoulders
Caution: Never exert pressure or strong anterior or posterior trac-
tion on the head, neck, or shoulders. Do not hook a finger into the
child’s axilla to deliver a shoulder. These maneuvers may result in
a brachial plexus injury (Erb or Duchenne), a hematoma of the neck,
or a shoulder injury.
●
Delivery of the shoulders should be deliberate. The shoul-
ders must rotate (or be rotated) to the anteroposterior diam-
eter of the outlet for delivery.
●
Gently depress the head toward the mother’s coccyx until the
anterior shoulder impinges against the symphysis. Then lift
the head upward. This aids delivery of the posterior shoulder.
●
The anterior shoulder is next delivered from behind the sym-
physis by gentle downward traction. The index and third fin-

●
Evaluate and resuscitate if necessary (Chapter 8) (Fig. 6-15).
●
Clamp and cut the cord when it ceases to pulsate (or sooner
if the infant is premature or in distress, or if isoimmuniza-
CHAPTER 6
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BENSON & PERNOLL’S
172 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
FIGURE 6-15. Resuscitation of the newborn.
tion is probable). Examine the umbilical cord for the nor-
mal two arteries and one vein. Apply a sterile cord clamp,
cord tie of umbilical tape, or rubber band distal to the skin
edge at the cord insertion at the umbilicus. Dress the cord
stump with dry gauze.
●
The newborn should be received into warm clean towels or
blankets, and avoid chilling. Apply means of identification
(e.g., bracelet).
●
At this point, bonding may be initiated with the parents hold-
ing the newborn. The mother may begin breastfeeding.
●
Next, perform newborn ocular prophylaxis (against gonor-
rhea and Chlamydia). Most commonly, erythromycin or
tetracycline ointment is used because they are more protec-
tive and provoke less ocular irritation than silver nitrate.
●
Examine the infant and record Apgar scores, weight, total

CHAPTER 6
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BENSON & PERNOLL’S
174 HANDBOOK OF OBSTETRICS AND GYNECOLOGY
Avoid traction on the cord before placental separation and do not
knead the fundus to separate the placenta (Credé maneuver). The
former may lead to cord laceration and the latter to hemorrhage,
uterine inversion, and shock. Maternal morbidity and mortality rates
increase with gross blood loss. A uterus that contracts and remains
contracted rarely bleeds excessively.
SEPARATION OF THE PLACENTA
The placenta is attached to the uterine wall only by anchoring villi
and thin-walled blood vessels, all of which eventually tear. In some
instances, the placental margin separates first. In others, when
the central portion of the placenta is initially freed bleeding from
the retroplacental sinuses may assist placental separation. Incom-
plete separation, usually due to ineffectual uterine contractions, may
allow the retroplacental blood sinuses to remain open, so that se-
vere blood loss may result.
Normal placental separation is manifested first by a firmly con-
tracting, rising fundus. The uterus becomes smaller and changes in
shape from discoid to globular. The umbilical cord becomes longer
as the placenta descends. There is a palpable and visible promi-
nence above the symphysis (if the bladder is empty) and a slight
gush of blood from the vagina. These signs normally appear within
about 3–4 min after delivery of the infant. The placenta should pres-
ent at the internal os after four or five firm uterine contractions,
whereupon it is expressed into the vagina for delivery.
These signs often are confused with other conditions: uterine

After several uterine contractions and a change in size and
shape indicate separation of the placenta, hold the clamp at
the vulva firmly with one hand, place the fingertips of the
other hand on the abdomen, and press between the fundus
and symphysis to elevate the fundus. If the placenta has sep-
arated, the cord will extrude into the vagina.
●
Further elevate the fundus, apply gentle traction on the cord,
and deliver the placenta from the vagina.
Manual Separation and Extraction of Placenta
Manual separation and extraction of the placenta from the fundus of
the uterus is an effective direct technique. This is invasive and, of-
ten, effective anesthesia is required. Manual removal of the placenta
should not be undertaken unless it is indicated and the operator is
experienced. Common indications for manual placental removal in-
clude: uterine hemorrhage, incomplete separation, prolonged reten-
tion, suspected uterine rupture, and retained placental segments.
●
Prepare the perineum and vulva again with detergent and
antiseptic solution.
●
Making the hand as narrow as possible, insert gently into
the vagina and palpate for defects in the vagina and cervix.
Slowly probe through the cervix with the fingers, taking care
not to lacerate the canal. (Brief moderately deep anesthesia
may be required if considerable delay has occurred.)
●
Locate and separate the placenta if this can be done easily.
Do not attempt to force cleavage against unusual resistance
(placenta accreta).

PPH may occur 24 h to 4 weeks after birth. Early PPH may be
caused by placental problems (abruptio placentae, placenta previa,
incomplete placental separation), uterine atony (anesthesia, marked
predelivery uterine distention, abnormal labor, prolonged or exces-
sive oxytocin administration, overdistended urinary bladder), lac-
eration(s) of the birth canal, rupture of the uterus, blood dyscrasias
(hypofibrogenemia), or mismanagement of the third stage of labor.
Usually, late postpartum hemorrhage is due to retained products of
conception. This complication occurs in 5%–10% of term deliver-
ies. About 2% of these patients must be readmitted to the hospital
for transfusion, and some require surgery. Further complications of
PPH include shock, anemia, and infection.
CLINICAL ASSESSMENT
The pulse rate should return to normal within the hour after deliv-
ery. Hence, a persistent slight tachycardia may indicate a signifi-
cant uncompensated blood loss. Elimination of the placenta and a
contracted uterus will restore at least 300 mL of blood to the ma-
ternal circulation. This normally causes a systolic elevation of
10–20 mm Hg for several hours after delivery. Therefore, persistent
hypotension suggests excessive blood loss, which may require re-
placement. Continued, even moderate postpartum hypertension, es-
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177