Normal Labor and Delivery

The Obstetrics and Gynecology Hospital of Fudan University

Jing-Xin Ding

Definition• Labor is the period from the onset of regular

uterine contractions until expulsion of the fetus and the placenta, and it is defined as that occurring after 28 completed weeks of gestation.

• Preterm delivery occurring after 28 weeks and before 37 completed weeks of gestation. In some developing countries, this time point has been advanced to 20 gestational weeks.

• Term delivery occurring after 37 weeks and before 42 completed weeks of gestation.

• Postterm delivery occurring after 42 completed weeks of gestation.

CHAPTER 1 THE HYPOTHESIS OF PARTURITION INITIATION

1. Mechanic theoryUTERINE QUIESCENCE During the early stage of

pregnancy, a remarkably period of myometrial quiescence is imposed.

CERVICAL SOFTENING By the end of pregnancy, easily distensible, increase in tissue compliance

Uterine awakening or activation

• During the end stage of pregnancy, the fetus compressed the lower segment and cervix, and mechanic effect induced the initiation of labor.

2. Endocrine theory• Some key endocrine proteins that control

contractility. • These proteins include the oxytocin and its

receptor, prostaglandin and its receptor, progesterone, and endothelin.

Fetal Contributions to Initiation of Parturition

• The ability of the fetus to provide endocrine signals that initiate parturition has been demonstrated in several species.

• This signal was shown to come from the fetal hypothalamic-pituitary-adrenal axis .

3. Neuromediator theory

• The uterine contraction is controlled by the autonomic nerve.

• It is still uncertain the role of autonomic nerve in the initiation of labor.

Summary• Culmination of a series of

biochemical changes in the uterus and cervix.

• Many hypothesis: • Not fully defined.

Mechanic theory

Endocrine theory

Neuromediator theory

THE FACTORS DECIDING LABOR AND DELIVERY

Force of the labor

Mental and psychological factors

Birth canal Fetus

CHAPTER 2

I Force of the labor

• Uterine Contractions — Main force • Maternal intra-abdominal pressure and the

contranction of levator ani — Ancillary forces

Characteristics of the uterine contractions

• Rhythmicity• Symmetry• Polarity• Retraction effect

1. Rhythmicity Each contraction increase progressively in intensity

and maintains the maxium intensity and then diminishes gradually.

• the uterine baseline tone -- from 8 to 12 mm Hg • 25 mm Hg at commencement of labor to 50 mm Hg at

the end of first stage • During second-stage labor, aided by maternal pushing,

contractions of 100 to 150 mm Hg are typical.

• At the beginning, the contracts occurs every 5-6 minutes, and last 30 s. With the progression of labor, frequency increases to every 1-2 min and the duration increases to 60 s when the cervix is fully dilated.

2. Symmetry The normal contractile wave

of labor originates near the uterine end of the fallopian tubes. Thus, these areas act as "pacemakers".

Contractions spread from the pacemaker area throughout the uterus at 2 cm/sec, depolarizing the whole uterus within 15 seconds.

3. Polarity

• Intensity is greatest in the fundus• Diminishes in the lower uterus.• Presumably, this descending gradient of pressure

serves to direct fetal descent toward the cervix.

4. Retraction effect • The muscle fiber retracts after contractions, and

the cavity of the uterus becomes small, and the fetus is forced to descend.

Maternal intra-abdominal pressure -- pushing

• Contraction of the abdominal muscles simultaneously with forced respiratory efforts with the glottis closed is referred to as pushing.

• After the cervix is dilated fully, the most important force.

• Accomplishes little in the first stage. It exhausts the mother, and its associated increased intrauterine pressures may be harmful to the fetus.

The contraction of levator ani contributes to:• the internal rotation, extention and expulsion of

the fetal head in the 2nd stage of labor• the delivery of placenta in the 3rd stage of labor.

II Birth canal• Bony Pelvis• The soft birthing canal

Bony Pelvis

The false pelvis above and the true pelvis below the linea terminalis.The true pelvis is formed by the sacrum and coccyx posteriorly and by the ischium and pubis laterally and anteriorly.

Pelvic Planes1.The pelvic inlet plane2.The mid plane of pelvis--the plane of least

diameter3.The pelvic outlet plane

The pelvic inlet plane• bordered by the pubic

crest anteriorly, the iliopectineal line of the innominate bones laterally, and the promontory of the sacrum posteriorly.

Four diameters: anteroposterior, transverse, and two oblique diameters.

• The obstetric conjugate of the inlet -- distance between the promontory of the sacrum and the symphysis pubis. -- 11 cm.

• The transverse diameter is constructed at right angles to the obstetrical conjugate and represents the greatest distance between the linea terminalis on either side.

• 2 oblique diameters extends from one of the sacroiliac synchondroses to the iliopectineal eminence on the opposite side.

• The most important -- most arrest of descent occur at this level.

It is bordered by the lower edge of the pubis anteriorly, the ischial spines and sacrospinous ligaments laterally, and the lower sacrum posteriorly.

The mid plane of pelvis--the plane of least diameter

• The interspinous diameter, 10 cm or slightly greater-- the smallest pelvic diameter.

The plane of the pelvic outlet • 2 approximately triangular areas with a common base• The apex of the posterior triangle is at the tip of the sacrum, and

the lateral boundaries are the sacrosciatic ligaments and the ischial tuberosities.

The anterior triangle is formed by the area under the pubic arch.

Important Diameters:• The transverse (bituberous) diameter extends between the

inner surfaces of the ischial tuberosities —an average of 9 cm• The posterior sagittal diameter — from the middle of the

transverse diameter to the sacrococcygeal joint —an average of 8.5 cm

If bituberous diameter < 9 cm , but the bituberous diameter + the posterior sagittal diameter >15 cm — delivered through the posterior triangle.

Pelvic axis

— an imaginary curved line that passes through the centers of the various diameters of the pelvis.

The pelvic axis first goes inferior and posterior, and then inferior, and then inferior and anterior.

Inclination of pelvis

— The angle which the plane of the pelvic inlet makes with the horizontal plane when the patient is standing.

The degree is usually 60 °, if it is too much, the engagement and delivery is difficult.

The soft birthing canal • the lower uterine

segments• the cervix• the vagina • the pelvic floor

Formation of the Lower Uterine Segments

— derived from the isthmus which is about 1 cm in nonpregnant uterus, and when the labor is started, with regular contractions of the upper uterine segment, it distended to 7 to 10cm.

the Physiological Retraction Ring• As a result of the lower segment thinning and

concomitant upper segment thickening, a boundary between the two is marked by a ridge on the inner uterine surface—the physiological retraction ring.

Cervical Changes• two fundamental changes—effacement and

dilatation • For an average-sized fetal head to pass through

the cervix, its canal must dilate to a diameter of approximately 10 cm.

Effacement of cervix• Cervical effacement is "obliteration" or "taking

up" of the cervix. • A length of about 2-3 cm canal -- a circular orifice

with almost paper-thin edges.

Dilatation of cervix

• Forebag of amnionic fluid is the leading portion of the amnionic sac and fluid located in front of the presenting part.

• As uterine contractions cause pressure on the membranes, the hydrostatic action of the amnionic sac in turn dilates the cervical canal.

A. Before labor, the primigravid cervix is long and undilated in contrast to that of the multipara, which has dilatation of the internal and external os.

B. As effacement begins, the multiparous cervix shows dilatation and funneling of the internal os. This is less apparent in the primigravid cervix.

C. As complete effacement is

achieved in the primigravid cervix, dilation is minimal. The reverse is true in the multipara.

Pelvic Floor Changes during Labor• Stretching of levator ani muscle fibers. • Thinning of the central portion of the perineum,

which becomes transformed from a wedge-shaped, 5-cm-thick mass of tissue to a thin, almost transparent membranous structure less than 1 cm thick.

III Fetus• Size of fetus• Fetal lie, presentation and position• Fetal abnormalities

FETAL HEAD Important sutures and fontanelles

• two frontal, two parietal, and two temporal bones, along with the occipital bone.

Sutures

The membrane-occupied spaces between the cranial bones are known as sutures.

FontanellesThe membrane-filled spaces

located at the point where the sutures intersect are known as fontanelles.

The anterior fontanelle (bregma) is at the intersection of the sagittal, frontal, and coronal sutures. It is diamond shaped and measures approximately 2×3cm, and it is much larger than the posterior fontanelle.

The posterior fontanelle is Y- or T-shaped and is found at the junction of the sagittal and lambdoid sutures.

• Clinically, they are useful in diagnosing the fetal head position.

Diameters

• Suboccipitobregmatic Diameter (9.5cm),-- extends from the undersurface of the occipital bone at the junction with the neck to the center of the anterior fontanelle. -- the presenting anteroposterior diameter when the head is well flexed, and it is the shortest anteroposterior diameter .

Occipitofrontal Diameter (11.3cm), extends from the external occipital protuberance to the glabella. The fetus usually engage by this diameter.

• Occipitomental Diameter (13.3cm), the presenting anteroposterior diameter in a brow presentation and the longest anteroposterior diameter of the head; it extends from the vertex to the chin.

• Biparietal Diameter (9.3cm), the largest transverse diameter; it extends between the parietal bones.

• This diameter detected by antenatal ultrasonic examination was used to estimate the size of the fetus.

2. Fetal lie and presentation• Fetal Lie. The lie is the relation of the long axis of

the fetus to that of the mother, and is either longitudinal or transverse.

• Fetal Presentation. The presenting part is that portion of the fetal body that is either foremost within the birth canal or in closest proximity to it.

3. Fetal abnormalities• When certain part of fetus is enlarged in fetal

abnormalities, for example, conjoined twins, hydrocephalus, dystocia will occur.

IV Maternal mental and psychological factors

• Psychologic support to the women during labor is very important.

• The provision of continuous psychologic support during labour by doulas, as well as nurses, family or friends is associated with improved maternal and fetal health and a variety of other benefits.

• A doula, also known as a labour coach, is a nonmedical person who assists a woman before, during or after childbirth, as well as her partner and/or family by providing information, physical assistance and emotional support.

CHAPTER 3 MECHANISM OF LABOR WITH OCCIPUT PRESENTATION

• The positional changes in the presenting part required to navigate the pelvic canal constitute the mechanisms of labor.

• Left occiput anterior (LOA) position is the most common fetal position

• The cardinal movements of labor are engagement, descent, flexion, internal rotation, extension, external rotation, and expulsion.

ENGAGEMENT • The mechanism by which the biparietal diameter—

the greatest transverse diameter in an occiput presentation—passes through the pelvic inlet is designated engagement.

• In nulliparous women, the fetal head engage 1 or 2 weeks before labor.

• In multiparous women, the fetal head usually engage after the onset of labor.

A normal-sized head usually does not engage with its sagittal suture directed anteroposteriorly. Instead, the fetal head usually enters the pelvic inlet either transversely or obliquely.

DESCENT • This movement is the first requisite for birth of the

newborn. • In nulliparas, engagement may take place before

the onset of labor, and further descent may not follow until the onset of the second stage.

• In multiparous women, descent usually begins with engagement.

Descent is brought about by one or more of four forces: (1) pressure of the amnionic fluid, (2) direct pressure of the fundus upon the breech with

contractions, (3) bearing down efforts of maternal abdominal

muscles (4) extension and straightening of the fetal body.

FLEXION • As soon as the descending head meets resistance,

whether from the cervix, walls of the pelvis, or pelvic floor, flexion of the head normally results.

• In this movement, the chin is brought into more intimate contact with the fetal thorax, and the appreciably shorter suboccipitobregmatic diameter is substituted for the longer occipitofrontal diameter.

INTERNAL ROTATION

• This movement consists of a turning of the head in such a manner that the occiput gradually moves toward the symphysis pubis anteriorly from its original position.

EXTENSION• After internal rotation, the sharply flexed head

reaches the vulva and undergoes extension. • When the head presses upon the pelvic floor,

however, two forces come into play.

• The first, exerted by the uterus, acts more posteriorly, and the second, supplied by the resistant pelvic floor and the symphysis, acts more anteriorly.

• The resultant vector is in the direction of the vulvar opening, thereby causing head extension.

• With progressive distention of the perineum and vaginal opening, an increasingly larger portion of the occiput gradually appears. The head is born as the occiput, bregma, forehead, nose, mouth, and finally the chin pass successively over the anterior margin of the perineum.

EXTERNAL ROTATION

• The delivered head next undergoes restitution. • If the occiput was originally directed toward the

left, it rotates toward the left.

• Restitution of the head to the oblique position is followed by completion of external rotation to the transverse position, a movement that corresponds to rotation of the fetal body, serving to bring its bisacromial diameter into relation with the anteroposterior diameter of the pelvic outlet. Thus, one shoulder is anterior behind the symphysis and the other is posterior.

EXPULSION • Almost immediately after

external rotation, the anterior shoulder appears under the symphysis pubis, and the perineum soon becomes distended by the posterior shoulder. After delivery of the shoulders, the rest of the body quickly passes.

• During labor, these movements are sequential but also show great temporal overlap.

• For example, as part of the process of engagement, there is both flexion and descent of the head.

• As a result, the fetus is transformed into a cylinder, with the smallest possible cross section passing through the birth canal.

Summary

• Preterm delivery occurring after 28 weeks and before 37 completed weeks of gestation. In some developing countries, this time point has been advanced to 20 gestational weeks.

• Term delivery occurring after 37 weeks and before 42 completed weeks of gestation.

• Postterm delivery occurring after 42 completed weeks of gestation.

THE FACTORS DECIDING LABOR AND DELIVERY

Force of the labor

Mental and psychological factors

Birth canal Fetus

Characteristics of the uterine contractions

• Rhythmicity• Symmetry• Polarity• Retraction effect

Formation of the Lower Uterine Segments

— derived from the isthmus which is about 1 cm in nonpregnant uterus, and when the labor is started, with regular contractions of the upper uterine segment, it distended to 7 to 10cm.

the Physiological Retraction Ring• As a result of the lower segment thinning and

concomitant upper segment thickening, a boundary between the two is marked by a ridge on the inner uterine surface—the physiological retraction ring.

Fetal lie and presentation• Fetal Lie. The lie is the relation of the long axis of

the fetus to that of the mother, and is either longitudinal or transverse.

• Fetal Presentation. The presenting part is that portion of the fetal body that is either foremost within the birth canal or in closest proximity to it.

• The positional changes in the presenting part required to navigate the pelvic canal constitute the mechanisms of labor.

• The cardinal movements of labor are engagement, descent, flexion, internal rotation, extension, external rotation, and expulsion.

CHAPTER 4 DIAGNOSIS OF THREATENED LABOR AND LABOR

THREATENED LABOR• Before actual labor begins, a number of

physiologic preparatory events usually occur. And these are called threatened labor.

The manifestation of threatened labor

• Lightening• False Labor• Bloody show

Lightening• Two or more weeks before labor, the fetal head

in most primigravid women settles into the brim of the pelvis. In multigravida, this often does not occur until early in labor.

• Lightening may be noted by the mother as a flattening of the upper abdomen and an increased prominence of the lower abdomen.

False Labor• During the last 4 to 8 weeks of pregnancy, the uterus undergoes

irregular contractions that normally are painless. • Such contractions appear unpredictably and sporadically and can be

rhythmic and of mild intensity. In the last month of pregnancy, these contractions may occur more frequently, and with greater intensity.

• These Braxton Hicks contractions are considered false labor in that they are not associated with progressive cervical dilatation or effacement.

• They may serve, however, a physiologic role in preparing the uterus and cervix for true labor.

Bloody show

• As a result of cervical effacement, the mucous plug within the cervical canal may be released. The onset of labor may thus be heralded by the passage of a small amount of blood-tinged mucus from the vagina (“bloody show”).

In Labor

• It is defined as progressive cervical effacement and dilatation resulting from regular uterine contractions that occur at least every 5 minutes and last 30 to 60 seconds.

STAGES OF LABOR

• Total stage of labor is from the onset of regular uterine contractions to the delivery of the baby and placenta.

3 stages of labor• The first stage is from the onset of true labor to complete

dilation of the cervix.primiparous patients: 11-12h, multiparous patients 6-8h.• The second stage is from complete dilation of the cervix to

the birth of the baby. primiparous patients: 1-2h, less than 2 h. multiparous patients

much faster, less than 1h.• The third stage is from the birth of the baby to delivery of the

placenta. 5-15min, less than 30 minutes.

CHAPTER 5 CLINICAL MANIFESTATION AND MANAGEMENT OF FIRST STAGE OF LABOR

CLINICAL MANIFESTATION OF THE FIRST STAGE

1. Regular uterine contraction. • From the onset of labor: occurs every 5-6 minutes and last

about 30 seconds. • With the progression of labor, the uterine contractions

increase progressively in intensity. Frequency increases to every 2-3 min. Duration increases to 50-60 seconds.

• When the cervix is nearly fully dilated, the contractions last to 1min or even longer, and rest for only 1-2 min.

2. Dilatation of cervix

-- determined by vaginal examination. Effacement of the cervix – Dilation10cm at the end of the 1st stage

3. Descent of fetal head• -- Determined by vaginal

examination. • The level—or station—of

the presenting fetal part in the birth canal is described in relationship to the ischial spines.

• At the level of the spines -- zero (0) station.

• 3,2and 1 cm above the ischial spines, the designation is –3, –2, –1.

• 1, 2,3 and 4cm blow the spines, as the presenting fetal part descends, it is then +1, +2, +3, +4.

4. Rupture of membranes

• Rupture of membranes usually occurs when the cervix is nearly fully dilated.

MANAGEMENT OF THE FIRST STAGE OF LABOR

• On admission the general condition of the patient is assessed, her pulse rate and blood pressure are recorded, and her urine is tested for protein.

• By abdominal examination the presentation and position of the fetus, and the relation of the presenting part to the brim of the pelvis, are determined.

• Abdominal examination will also show the frequency and strength of the uterine contractions. The fetal heart rate is counted for a full minute, and any abnormality of rate or rhythm is noted.

• A vaginal examination will show the degree of dilatation of the cervix, whether the membrane are intact or ruptured, and the level and position of the presenting part.

Partogram

• Once the labor has become established, all events during labor are noted on a partogram—a most useful graphical record of the course of labor.

• The alarm line• The management line

Uterine Activity • Uterine contractions should be monitored every

30 minutes by palpation for their frequency, duration, and intensity.

• This either an external tocodynamometercan be achieved electronically using or an internal pressure catheter in the amniotic cavity.

Fetal Monitoring • The fetal heart rate should be evaluated by either

auscultation with a DeLee stethoscope, by external monitoring with Doppler equipment, or by internal monitoring with a fetal scalp electrode.

• In patients with no significant obstetric risk factors, the fetal heart rate should be auscultated or the electronic monitor tracing evaluated every 1-2h in the latent phase of labor, and at least every 15-30 minutes in the active phase of the first stage of labor and at least every 15 minutes in the second stage of labor.

DILATION OF CERVIX AND DESCENT OF FETAL HEAD

Measurement of progress • During the first stage, the progress of labor may

be measured in terms of cervical effacement, cervical dilatation, and descent of the fetal head.

Phases

• Latent phase, during which cervical effacement and early dilatation(to 3cm) occur

• Active phase, during which more rapid cervical dilatation occurs, the cervix dilate from 3cm to 10cm.

The active phase has 3 component parts

• acceleration phase the cervix dilates from 3-4cm, normally takes 1h and 30 min.

• maximum acceleration phase the cervix dilates from 4-9cm, normally takes 2h.

• deceleration phase the cervix dilates from 9-10cm, normally takes 30 min.

Length • The length of the first stage may vary in

relation to parity; primiparous patients generally experience a longer first stage than do multiparous patients. • This phase normally takes 8h, and the

maximum is 16 h in primiparous patients.

• The active phase begins when the cervix is 3 cm dilated. The minimal dilatation during the active phase of the first stage is nearly the same for primiparous and multiparous women: 1 and 1.2cm/hour, respectively.

• This phase normally takes 4h, and the maximum is 8 h.

Descent of fetal head • The level—or station—of the presenting fetal

part in the birth canal is described in relationship to the ischial spines.

• The descent of fetal head is not obvious in the latent phase, and is accelerated in the active phase, usually 0.86cm/h.

Rupture of membranes• Rupture of membranes usually occurs when the

cervix is nearly fully dilated. • Once the membrane is ruptured, the fetal heart

should be monitored, and the color and amount of Amnionic Fluid should be noted.

• And the time of rupture should be recorded.

Blood Pressure

• During uterine contractions, the maternal blood pressure usually elevated 5-10 mmHg. The blood pressure should be monitored every 4-6 hours once the labor is started.

Maternal Position• If the head is engaged there is no need for the patient to

remain in bed during early labor. If she is up and about, the weight of the liquor and fetus helps to dilate the cervix, and pressure on the lower segment stimulates the uterus to contract.

• If she is lying in bed, the lateral recumbent position should be encouraged to ensure perfusion of the uteroplacental unit.

Vaginal Examination • During the latent phase, every 4 hours• In the active phase, every 2 hours• Cervical effacement and dilatation, the station and

position of the presenting part should be recorded.

Amniotomy (The artificial rupture of fetal membranes )

• Provide information on the volume of amniotic fluid and the presence or absence of meconium. In addition, rupture of the membranes may cause an increase in uterine contractility.

• Amniotomy incurs risks of chorioamnionitis if labor is prolonged and of umbilical cord compression or cord prolapse if the presenting part is not engaged.

CHAPTER 6 CLINICAL MANIFESTATION AND MANAGEMENT OF SECOND STAGE OF LABOR

• This stage begins when cervical dilatation is complete and ends with fetal delivery.

CLINICAL MANIFESTATION• Bear down -- the urge to defecate.• Uterine contractions may now last 1minute

or longer and recur at an interval no longer than 1 minute.• The abdominal pressure, together with the

uterine contractile force, combines to expel the fetus.

Head visible on vulval gapping -- the fetal head is seen at the vulva at the height of each contraction. Between the contractions the elastic tone of the perineal muscles push the head back .

• The perineal body and vulval outlet become more and more stretched, and the encirclement of the largest head diameter by the vulvar ring is known as crowning of head.

• Descent, flexion, internal rotation, extension, external rotation, and expulsion.

• The second stage generally takes from 1 to 2 hours in primigravid women and from 5 to 60 minutes in multigravid women.

MANAGEMENT OF THE SECOND STAGE

Fetal Monitoring • During the second stage, the fetal heart rate

should be monitored continuously or evaluated every 5-10 minutes.

Bearing Down • With each contraction, the mother should be

encouraged to hold her breath and bear down with expulsive efforts.

Vaginal Examination • Progress should be recorded approximately every

30 minutes during the second stage. -- the descent and flexion of the presenting part, the extent of internal rotation.

• Cervix is no longer palpable.

Delivery of the Fetus • When delivery is imminent, the

patient is usually placed in the lithotomy position, and the skin over the lower abdomen, vulva, anus, and upper thighs is cleansed with an antiseptic solution.

The modified Ritgen maneuver

• Prevent it being born suddenly, and the head must be kept flexed. • One hand is used to exert forward pressure on the chin of the fetus through the

perineum. Concurrently, the other hand exerts pressure superiorly against the occiput. The downward pressure increases flexion of the head and allows a controlled delivery. This maneuver is designated the modified Ritgen maneuver.

• After the airway has been cleared, an index finger is used to check whether the umbilical cord encircles the neck. If so, the cord can usually be slipped over the infant’s head. If the cord is too tight, it can be cut between two clamps.

• Then the shoulders descend and rotate into the anteroposterior diameter of the pelvis.

• Delivery of the anterior shoulder is aided by gentle downward traction on the externally rotated head. The brachial plexus may be injured if excessive force is used. The posterior shoulder is delivered by elevating the head. Finally, the body is slowly extracted by traction on the shoulders.

EPISIOTOMYEpisiotomy -- incision of the perineum.Indication: • The perineum is tight or the fetus is big.• To accelate the delivery of the fetus.Median midline episiotomy or Postero-lateral

episiotomy.

CHAPTER 7 CLINICAL MANIFESTATION AND MANAGEMENT OF THIRD STAGE OF LABOR

clinical manifestation: placental separation

Signs of placental separation(1) A fresh show of blood from the vagina,(2) The fundus of the uterus rises up and the uterus

becomes firm and globular.(3) The umbilical cord lengthens outside the vagina, (4) The cord does not retract when press the lower

segment of the uterus.

2 Mechanisms of placenta separation and expulsion

• Schultze mechanism more common, the fetal side of the placenta expelled first.

• Duncan mechanism less common, the maternal side of the placenta expelled first.

Management

• Management of the newborn’s respiratory tractThe mouth and pharynx are sucked clear with a

mucus extractor. A healthy baby breathes and cries very soon after it is born.

Management of the cordThe cord is clamped and cut within 15 to 20 seconds.

Delayed cord clamping can result in neonatal hyperbilirubinemia.

The newborn is then placed under an infant warmerA plastic clamp that is safe, efficient, and fairly inexpensive,

is widely used.

APGAR SCORE• This scoring system is a useful clinical tool to

identify those neonates who require resuscitation as well as to assess the effectiveness of resuscitative measures.

APGAR SCORE Sign 0 1 2

1. Heart rate Absent <100 beats/min >100 beats/min

2. Respiratory effort Absent Slow, irregular Good, crying

3. Muscle tone Flaccid Some flexion of extremities Active motion

4. Reflex irritability (response to stimulation of sole of foot)

None Grimace Vigorous cry

5. Color Pale, blue Body,pink; extremities, blue

Completely pink

• Apgar score 8-10 Normal• Apgar score 4-7 asphyxia livida , blue asphyxia—

clear air, artificial respiration ， give O2,drug• Apgar score 0-3 asphyxia pallida, white asphyxia

—resuscitation, endotracheal intubation

• The 1-minute Apgar score reflects the need for immediate resuscitation.

• The 5-minute score, and particularly the change in score between 1 and 5 minutes, is a useful index of the effectiveness of resuscitative efforts.

• The 5-minute Apgar score also has prognostic significance for neonatal survival.

Assist the delivery of placenta

The mother may be asked to bear down, and the intra-abdominal pressure may be adequate to expel the placenta.

If these efforts fail, then pressure is exerted with the hand on the fundus to propel the detached placenta into the vagina.

Traction on the umbilical cord must not be used to pull the placenta out of the uterus.

• The placenta is then gently lifted away from the introitus. Care is taken to prevent the membranes from being torn off and left behind. If the membranes start to tear, they are grasped with a clamp and removed by gentle teasing.

• Examination of the Placenta and the membraneTo ensure its complete removal and to detect placental

abnormalities.• Examination of the soft birth canalThe cervix and vagina should be thoroughly inspected for

lacerations and surgical repair performed if necessary.

• Prophylaxis of postpartum hemorrhageUterine massage and the use of oxytocin. If the patient is at risk of postpartum, manual

removal of the placenta may be necessary.

Summary

THREATENED LABOR• Before actual labor begins, a number of

physiologic preparatory events usually occur. And these are called threatened labor.

The manifestation of threatened labor

• Lightening• False Labor• Bloody show

In Labor• It is defined as progressive cervical effacement

and dilatation resulting from regular uterine contractions that occur at least every 5 minutes and last 30 to 60 seconds.

STAGES OF LABOR

• Total stage of labor is from the onset of regular uterine contractions to the delivery of the baby and placenta.

3 stages of labor• The first stage is from the onset of true labor to complete

dilation of the cervix.primiparous patients: 11-12h, multiparous patients 6-8h.• The second stage is from complete dilation of the cervix to

the birth of the baby. primiparous patients: 1-2h, less than 2 h. multiparous patients

much faster, less than 1h.• The third stage is from the birth of the baby to delivery of the

placenta. 5-15min, less than 30 minutes.

Phases

• Latent phase, during which cervical effacement and early dilatation(to 3cm) occur

• Active phase, during which more rapid cervical dilatation occurs, the cervix dilate from 3cm to 10cm.

The active phase has 3 component parts

• acceleration phase the cervix dilates from 3-4cm, normally takes 1h and 30 min.

• maximum acceleration phase the cervix dilates from 4-9cm, normally takes 2h.

• deceleration phase the cervix dilates from 9-10cm, normally takes 30 min.

Length • The length of the first stage may vary in

relation to parity; primiparous patients generally experience a longer first stage than do multiparous patients. • This phase normally takes 8h, and the

maximum is 16 h in primiparous patients.

• The active phase begins when the cervix is 3 cm dilated. The minimal dilatation during the active phase of the first stage is nearly the same for primiparous and multiparous women: 1 and 1.2cm/hour, respectively.

• This phase normally takes 4h, and the maximum is 8 h.

Head visible on vulval gapping -- the fetal head is seen at the vulva at the height of each contraction. Between the contractions the elastic tone of the perineal muscles push the head back .

• The perineal body and vulval outlet become more and more stretched, and the encirclement of the largest head diameter by the vulvar ring is known as crowning of head.

• Descent, flexion, internal rotation, extension, external rotation, and expulsion.

• The second stage generally takes from 1 to 2 hours in primigravid women and from 5 to 60 minutes in multigravid women.

Signs of placental separation(1) A fresh show of blood from the vagina,(2) The fundus of the uterus rises up and the uterus

becomes firm and globular.(3) The umbilical cord lengthens outside the vagina, (4) The cord does not retract when press the lower

segment of the uterus.

APGAR SCORE• This scoring system is a useful clinical tool to

identify those neonates who require resuscitation as well as to assess the effectiveness of resuscitative measures.

APGAR SCORE Sign 0 1 2

1. Heart rate Absent <100 beats/min >100 beats/min

2. Respiratory effort Absent Slow, irregular Good, crying

3. Muscle tone Flaccid Some flexion of extremities Active motion

4. Reflex irritability (response to stimulation of sole of foot)

None Grimace Vigorous cry

5. Color Pale, blue Body,pink; extremities, blue

Completely pink

• Apgar score 8-10 Normal• Apgar score 4-7 asphyxia livida , blue asphyxia—

clear air, artificial respiration ， give O2,drug• Apgar score 0-3 asphyxia pallida, white asphyxia

—resuscitation, endotracheal intubation

丁景新 Jingxin DingEmail: djxdd@sina.com