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Normal Labor and Delivery

Practice Essentials

Labor is a physiologic process during which the fetus, membranes, umbilical cord, and placenta are expelled from the uterus.

Stages of labor

Obstetricians have divided labor into 3 stages that delineate milestones in a continuous process.

First stage of labor

Begins with regular uterine contractions and ends with complete cervical dilatation at 10 cm

Divided into a latent phase and an active phase

The latent phase begins with mild, irregular uterine contractions that soften and shorten the cervix

Contractions become progressively more rhythmic and stronger

The active phase usually begins at about 3-4 cm of cervical dilation and is characterized by rapid cervical dilation and descent of the presenting fetal part

Second stage of labor

Begins with complete cervical dilatation and ends with the delivery of the fetus

In nulliparous women, the second stage should be considered prolonged if it exceeds 3 hours if regional anesthesia is administered or 2 hours in the absence of regional anesthesia

In multiparous women, the second stage should be considered prolonged if it exceeds 2 hours with regional anesthesia or 1 hour without it

Third stage of labor

The period between the delivery of the fetus and the delivery of the placenta and fetal membranes

Delivery of the placenta often takes less than 10 minutes, but the third stage may last as long as 30 minutes

Expectant management involves spontaneous delivery of the placenta

The third stage of labor is considered prolonged after 30 minutes, and active intervention is commonly considered

Active management often involves prophylactic administration of oxytocin or other uterotonics (prostaglandins or ergot alkaloids), cord clamping/cutting, and controlled traction of the umbilical cord

Mechanism of labor

The mechanisms of labor, also known as the cardinal movements, involve changes in the position of the fetus’s head during its passage in labor. These are described in relation to a vertex presentation. Although labor and delivery occurs in a continuous fashion, the cardinal movements are described as the following 7 discrete sequences
:

Engagement

Descent

Flexion

Internal rotation

Extension

Restitution and external rotation

Expulsion

History

The initial assessment of labor should include a review of the patient’s prenatal care, including confirmation of the estimated date of delivery. Focused history taking should elicit the following information:

Frequency and time of onset of contractions

Status of the amniotic membranes (whether spontaneous rupture of the membranes has occurred, and if so, whether the amniotic fluid is clear or meconium stained)

Fetal movements

Presence or absence of vaginal bleeding.

Braxton-Hicks contractions must be differentiated from true contractions. Typical features of Braxton-Hicks contractions are as follows:

Usually occur no more often than once or twice per hour, and often just a few times per day

Irregular and do not increase in frequency with increasing intensity

Resolve with ambulation or a change in activity

Contractions that lead to labor have the following characteristics:

May start as infrequently as every 10-15 minutes, but usually accelerate over time, increasing to contractions that occur every 2-3 minutes

Tend to last longer and are more intense than Braxton-Hicks contractions

Lead to cervical change

Physical examination

The physical examination should include documentation of the following:

Maternal vital signs

Fetal presentation

Assessment of fetal well-being

Frequency, duration, and intensity of uterine contractions

Abdominal examination with Leopold maneuvers

Pelvic examination with sterile gloves

Digital examination allows the clinician to determine the following aspects of the cervix:

Degree of dilatation, which ranges from 0 cm (closed or fingertip) to 10 cm (complete or fully dilated)

Effacement (assessment of the cervical length, which can be reported as a percentage of the normal 3- to 4-cm–long cervix or described as the actual cervical length)

Position (ie, anterior or posterior)

Consistency (ie, soft or firm)

Palpation of the presenting part of the fetus allows the examiner to establish its station, by quantifying the distance of the body (-5 to +5 cm) that is presenting relative to the maternal ischial spines, where 0 station is in line with the plane of the maternal ischial spines.

Intrapartum management of labor

First stage of labor

On admission to the Labor and Delivery suite, a woman having normal labor should be encouraged to assume the position that she finds most comfortable. Possibilities including the following:

Walking

Lying supine

Sitting

Resting in a left lateral decubitus position

Management includes the following:

Periodic assessment of the frequency and strength of uterine contractions and changes in cervix and in the fetus’ station and position

Monitoring the fetal heart rate at least every 15 minutes, particularly during and immediately after uterine contractions; in most obstetric units, the fetal heart rate is assessed continuously

Second stage of labor

With complete cervical dilatation, the fetal heart rate should be monitored or auscultated at least every 5 minutes and after each contraction.
Prolonged duration of the second stage alone does not mandate operative delivery if progress is being made, but management options for second-stage arrest include the following:

Continuing observation/expectant management

Operative vaginal delivery by forceps or vacuum-assisted vaginal delivery, or cesarean delivery.

Delivery of the fetus

Positioning of the mother for delivery can be any of the following
:

Supine with her knees bent (ie, dorsal lithotomy position; the usual choice)

Lateral (Sims) position

Partial sitting or squatting position

On her hands and knees

Episiotomy used to be routinely performed at this time, but current recommendations restrict its use to maternal or fetal indications

Delivery maneuvers are as follows:

The head is held in mid position until it is delivered, followed by suctioning of the oropharynx and nares

Check the fetus’s neck for a wrapped umbilical cord, and promptly reduce it if possible

If the cord is wrapped too tightly to be removed, the cord can be double clamped and cut

The fetus’s anterior shoulder is delivered with gentle downward traction on its head and chin

Subsequent upward pressure in the opposite direction facilitates delivery of the posterior shoulder

The rest of the fetus should now be easily delivered with gentle traction away from the mother

If not done previously, the cord is clamped and cut

The baby is vigorously stimulated and dried and then transferred to the care of the waiting attendants or placed on the mother’s abdomen

Third stage of labor

The following 3 classic signs indicate that the placenta has separated from the uterus
:

The uterus contracts and rises

The umbilical cord suddenly lengthens

A gush of blood occurs

Delivery of the placenta usually happens within 5-10 minutes after delivery of the fetus, but it is considered normal up to 30 minutes after delivery of the fetus.

Pain control

Agents given in intermittent doses for systemic pain control include the following
:

Meperidine, 25-50 mg IV every 1-2 hours or 50-100 mg IM every 2-4 hours

Fentanyl, 50-100 mcg IV every hour

Nalbuphine, 10 mg IV or IM every 3 hours

Butorphanol, 1-2 mg IV or IM every 4 hours

Morphine, 2-5 mg IV or 10 mg IM every 4 hours

As an alternative, regional anesthesia may be given. Anesthesia options include the following:

Epidural

Spinal

Combined spinal-epidural

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