• Clinical science

Childbirth

Abstract

Childbirth begins with the onset of labor, which consists of contractions that lead to progressive cervical dilation and effacement, eventually resulting in the birth of the infant and expulsion of the placenta. Complications of childbirth include arrest of or prolonged labor, premature rupture of membranes and preterm premature rupture of membranes, and nerve injuries. The clinical status of the mother and fetus should be consistently monitored during childbirth. While vaginal delivery is typically preferred, cesarean section may be indicated for certain deliveries.

Normal spontaneous labor

Obstetric contractions (uterine muscle contractions)

Time Characteristics

Uterine contractions during pregnancy

Alvarez-waves
  • Physiological; occurs after 20 weeks of pregnancy
  • Low intensity, high frequency
Braxton Hicks contractions
  • Physiological; occur after 20 weeks of pregnancy
  • High intensity
  • Tetanic (sustained muscle contraction) in nature
  • Diffuse abdominal tightening
  • Last for 1 minute at the most
  • Frequency: typically ≤ 2 times / hour; may become more frequent near term (false labor)
False labor
  • 3–4 weeks before birth
  • Uncoordinated uterine contractions of moderate intensity (helps with fetal positioning)
  • Cervical changes are absent
  • Contractions do not increase in frequency, intensity, or duration
  • Easily relieved with analgesia
Prelabor
  • 3–4 days before birth
  • Irregular contractions of high intensity, which occur every 5–10 min shortly before phase 1 begins. They are responsible for correctly positioning the fetal head in the pelvis.
Labor Stage 1: cervical dilation and effacement
  • Onset of normal childbirth.
  • Coordinated, regular, rhythmic contractions of high intensity; occur approximately every 10 minutes. Shortly before stage 2, they occur every 2–3 min. These contractions are responsible for cervical dilation.
Stage 2: fetal expulsion
  • After complete cervical dilation and effacement
  • Coordinated and regular contractions of high intensity; occur approximately every 4–10 min and are responsible for fetal expulsion. Towards the end of the stage, they occur very often (every 2–3 minutes) and are of higher intensity (pressure greater than 200 mm Hg).
Stage 3: placental expulsion or afterbirth
  • Several minutes after childbirth
  • Irregular contractions of very low intensity, which force the placenta through the vaginal canal within 30 min after fetal expulsion
Afterpains
  • Several days after childbirth
  • Irregular contractions of varying intensity, which cause uterine involution and bleeding cessation

False labor only requires reassurance!

Stages of labor

First stage

  • Definition: period from the onset of labor until complete dilation of the cervix has occurred
  • Phases
    • Latent Phase
      • Occurs during onset of labor (regular contraction) → ends at 6 cm of cervical dilation
      • Characterized by mild, infrequent, irregular contractions with gradual change in cervical dilation (< 1 cm per hour).
      • Duration
        • Primipara: < 20 hours
        • Multipara: < 14 hours
    • Active Phase
      • Occurs after the latent phase at ≥ 6 cm of cervical dilation → ends with complete (∼ 10 cm) cervical dilation
      • Characterized by an increase in the rate of cervical dilation (1–4 cm per hour)
      • Duration
        • Primipara: ≥ 1.2 cm/hour
        • Multipara: ≥ 1.5 cm/hour
  • Clinical features
    • Cervix effaces and shortens → cervical dilation
    • Bloody show: A blood-tinged mucous plug may be discharged when the cervix shortens and dilates.
    • Spontaneous rupture of membranes: Watery discharge (caused by rupture of amniotic sac) usually occurs during the onset of labor.
  • Management
    • Analgesia at request
    • Fetal heart rate monitoring
    • Determine fetal position with abdominal (see Leopold's maneuvers) and pelvic (palpation of fetal sutures/fontanelles) examination
      • If fetal position cannot be determined by examination, perform ultrasound
    • Regular assessment of cervical dilation and descent of the fetal head
    • Amniotomy may be performed during the active phase if the fetal head is well applied (lying against the cervix).

Second stage

  • Definition: a stage of labor that begins once the cervix is completely dilated and ends with the birth of the infant
  • Duration
    • Primipara: < 3 hours
    • Multipara: < 2 hours
  • Clinical features
    • Completely dilated cervix
    • Regular uterine contractions increasing in frequency and intensity
    • Crowning: the appearance of the fetus's head at the vaginal opening as contractions progress
  • Management
    • Warm compresses and perineal massage
    • Assist the mother to find any comfortable and safe position.
    • Episiotomy: not routinely performed
      • Definition: usually a midline incision of the perineum to enlarge the vaginal opening during delivery
      • Indications: shoulder dystocia, forceps or vacuum-assisted delivery, or vaginal breech delivery
    • Delay cord clamping for ∼ 1 minute; alternatively milk the cord (to enhance blood transfusion to the newborn )

Third stage

  • Definition: stage of labor that begins with the birth of the infant and lasts until the complete expulsion of the placenta
  • Duration: 30 minutes
  • Clinical features
    • Uterine contractions (in order to expel the placenta)
    • Signs of placental separation:
      • Cord lengthening
      • Gush of vaginal blood (usually accompanied a blood loss of 300 mL)
      • Uterine fundal rebound (the uterus becomes less elongated and more spherical)

Fourth stage

References:[1][2][3][4][5][6][7][8][9][10][11]

Abnormal labor

Etiology

  • Abnormalities of the 3 P's of labor
    • Pelvis: size and shape of the maternal pelvis (e.g., small bony pelvis)
    • Passenger: size and position of the infant (e.g., fetal macrosomia or abnormal orientation)
    • Power: strength and frequency of contractions (e.g., dysfunctional contractions )

First stage of labor

Prolonged latent phase

  • Diagnosis: poor acceleration phase with a cervical dilation ≤ 6 cm
    • > 20 hours in a primipara
    • > 14 hours in a multipara
  • Management
    • Rest, hydration, and adequate analgesia
    • Oxytocin may be considered in well-rested mothers if the other measures have been implemented.

Prolonged active phase

  • Etiology: abnormalities of the 3 P's of labor
  • Diagnosis: ≥ 6 cm cervical dilation with dilation < 1.2 cm per hour in a primipara or < 1.5 cm per hour in a multipara
  • Management
    • Augmentation with oxytocin for hypotonic contractions
    • Analgesia for hypertonic contractions

Arrested active phase

  • Etiology: abnormalities of the 3 P's of labor
  • Diagnosis: ≥ 6 cm cervical dilation with ruptured membranes and no cervical change for ≥ 4 hours if adequate contractions are present; or no cervical change for > 6 hours if only inadequate contractions are present
  • Management: cesarean section

Prolonged second stage of labor

  • Etiology: abnormalities of the 3 P's of labor
  • Diagnosis: failed delivery of the baby after 3 hours in a primipara and after 2 hours in a multipara (an extra hour may be added if an epidural was administered)
  • Management
    • Augmentation with oxytocin if uterine contractions are inadequate and progress is > 1 cm after 60–90 minutes of pushing
    • Trial of forceps or vacuum delivery if the fetal head is engaged AND maternal contractions are adequate
    • Cesarean section if the fetal head is not engaged

Complications of a prolonged second stage are postpartum hemorrhage and a poor neonatal outcome!

Prolonged third stage of labor

If the placenta is incomplete or if an accessory placenta is suspected, manual palpation should be performed and any remaining tissue should be removed by curettage!

References:[12][13][14]

Rupture of membranes

Types

Premature rupture of membranes (PROM)

Delayed rupture of membranes

Preterm premature rupture of membranes (PPROM)

Clinical features

  • Sudden “gush” of pale yellow or clear fluid from the vagina (may also be a constant leaking sensation)

Diagnosis

  • Sterile speculum examination
    • Positive pool: amniotic fluid exiting the cervix and pooling in the vaginal fornix
    • Detection of amniotic fluid: during sterile speculum examination
      • Litmus test or nitrazine test: test strips turn blue
      • Positive fern test: fern pattern on glass slide
      • Positive IGF1: IGF1, normally present in amniotic fluid, appears in the cervix if membranes rupture.
  • Ultrasound: Oligohydramnios may be present.

Management

Tocolysis is contraindicated in advanced labor (cervical dilation > 4cm), chorioamnionitis, nonreassuring fetal signs, abruptio placentae, or risk of cord prolapse!

References:[15][2][16][17][18][19][20][21][22]

Intrapartum fetal monitoring

Cardiotocography

  • Widely used diagnostic tool during 3rd trimester and labour to detect signs of fetal distress
  • Procedure
    • Determination of the fetal heart rate (FHR), presence of acceleration or deceleration by Doppler ultrasound, recording beats per minute in the upper curve (cardiogram)
    • During birth, the FHR may be monitored internally via an electrode that is attached to the fetal head (fetal scalp electrode); rupture of the membranes must have occurred or an amniotomy performed.
    • Mechanoelectrical measurement of uterine contractions via a pressure transducer, recording in the lower curve in kPa (tocodynagraph)
  • Indications

Fetal heart rate

Acceleration (CTG)

  • A normal temporal increase in the FHR from the baseline by >15 bpm for a maximum duration of 10 minutes.

Decelerations (CTG)

MNEMONIC for fetal HR monitoring: VEAL CHOP
Variable decelerations Cord compression/prolapse
Early decelerations Head compression
Accelerations OK, maybe O2
Late decelerations Placental insufficiency/Problem

Oscillation amplitude

The oscillation amplitude is also known as bandwidth. It is defined as the difference between the highest and lowest turning point of the FHR curve. Accelerations and decelerations are not noted.

  • Saltatoric oscillations: > 25 bpm
  • Undulatory oscillations: 10–25 bpm
    • Normal findings
  • Impaired-undulatory oscillations: 5–10 bpm
    • Causes: fetus is asleep, sedating medication, hypoxia
    • Identical reasons as for impaired-undulatory oscillations
  • Silent oscillations: <5 bpm

References:[23][24][25][26][2][27][27][28][29][30][31][32][33][34][35]

Induction of labor

Score
0 points 1 point 2 points 3 points
Cervical position Posterior Midline Anterior
Cervical consistency Firm Moderately firm Soft (ripe)
Cervical effacement Up to 30% 31–50% 51–80% > 80%
Cervical dilation closed or 0 cm 1–2 cm 3–4 cm > 5 cm
Fetal station - 3 cm - 2 cm - 1/0 cm + 1/+ 2 cm
  • Approach
    • Membrane sweeping (shortens time to onset of labor)
    • If the cervix is still unfavorable: cervical ripening with prostaglandin E1 or E2 (e.g., misoprostol)
    • Maternal oxytocin infusion
    • Consider amniotomy (only if the cervix is partially dilated and completely effaced, and the fetal head is well applied)
    • Administer under fetal heart rate monitoring.

References:[36]

Assisted vaginal delivery

Obstetric forceps delivery

  • Definition: a forcep is a metal device that enables gentle rotation and/or traction of the fetal head during vaginal delivery
  • Types
    • Kielland: enables rotation and traction of the fetal head
    • Simpson: only enables traction of the fetal head
    • Barton: used for occiput transverse position of the fetal head
    • Piper: used to deliver the fetal head during breech delivery
  • Classification (See “Station” in “Mechanics of childbirth”)
    • Outlet: fetal head lies on the pelvic floor
    • Low: fetal head is below +2 station (not on the pelvic floor)
    • Mid: fetal head is below 0 station (not at +2 station)
    • High: fetal head is not engaged
  • Indications
  • Prerequisites
    • Skilled clinician
    • Clinically adequate pelvic dimensions (see “Mechanics of childbirth”)
    • Full cervical dilation
    • Engagement of the fetal head
    • Knowledge of exact position and attitude of the fetal head
    • Emptied maternal bladder
    • No suspicion of fetal bleeding or bone mineralization disorders
  • Advantages (compared to vacuum delivery)
    • Scalp injuries are less common
    • Cannot undergo decompression and “pop off”
  • Complications

Vacuum extractor delivery

  • Definition: a vacuum extractor is a metal or plastic cup, attached to the fetal head with a suction device, that enables traction of the fetal head during vaginal delivery
  • Indications
  • Prerequisites
    • Skilled clinician
    • Clinically adequate pelvic dimensions
    • Gestation ≥ 34 weeks
    • Engagement of the fetal head
    • Full cervical dilation
    • Emptied maternal bladder
    • Vertex position
    • No suspicion of fetal bleeding or bone mineralization disorders
  • Advantages (compared to forceps delivery)
    • Requires minimum space
    • incidence of third- and fourth-degree perineal tears
    • Less knowledge about exact position and attitude of the fetal head is acceptable
  • Complications
    • Maternal: suction of maternal soft tissue → hematomas or lacerations
    • Fetal: cephalohematoma , scalp lacerations, life-threatening head injury (e.g., intracranial hemorrhage or subgaleal hematoma)

A routine episiotomy is not recommended with assisted vaginal delivery because of the risk of poor healing and anal sphincter injury!

An advantage of assisted vaginal delivery is avoiding cesarean section!

References:[37][5]

Cesarean section (c-section)

Overview

  • Definition: the delivery of a newborn through a vertical or horizontal incision in the lower abdominal and uterine wall
  • Advantages
    • Safest method of birth if maternal and/or fetal health is compromised by a vaginal delivery
    • Fetal birth trauma is rare.
  • Disadvantages

Indications

Type of cesarean Maternal indications Fetal indications
Primary cesarean section
Secondary cesarean section (after PROM and/or onset of phase 1)
  • Prolonged labor in:
Emergent cesarean section
  • Pathological CTG (particularly persistent, severe fetal bradycardia)
  • Fetal acidosis
  • Immediate threat to life of mother or fetus

Types of incisions

Definition Advantages Disadvantages

Low segment transverse

  • Lateral incision of the lower anterior abdomen and noncontractile uterine fundus
  • ↓ Risk of:
    • Adhesions
    • Hemorrhage
  • Trial of labor in subsequent pregnancy is possible, in the absence of any conditions requiring cesarean section
  • Better cosmetic appearance
Classical
  • Transverse incision of the anterior abdomen and contractile uterine fundus
  • May be performed in the presence of lower segment pathologies (e.g., myoma)
  • Fetus can be delivered regardless of lie
  • Easily allows extension of incision intraoperatively
  • Shorter incision-to-delivery period
  • ↑ Risk of:
    • Rupture in subsequent pregnancies
    • Hemorrhage
    • Adhesions
  • Two types of transverse incisions
    • Pfannenstiel incision (common): 2–3 cm above the symphysis pubis and slightly curved
    • Joel-Cohen incision (Misgav Ladach): 3 cm below the anterior superior iliac spine line and straight

Procedure

  • Cesarean section is usually performed through a lateral incision.
    • Skin incision above the pubic symphysis.
    • Largely blunt penetration through the abdominal muscles, fascia, and peritoneum
    • Hysterotomy
    • Fetal extraction, cord clamping, and manual placental removal
    • Wound closure
  • Procedural Time: fetal extraction within ∼ 3–10 min

Complications

There are guidelines detailing indications for cesarean section that are based on scientific findings. However, each hospital can individually determine how these indications are interpreted. The well-being of the mother and child should be of the utmost priority!

References:[38][39][40][41][42]

Obstetric complications during childbirth

Obstetric lacerations

Severity Description
First degree cutaneous to subcutaneous tissue tear (skin, fourchette, posterior vaginal wall) with no involvement of the perineal muscles
Second degree previous structures and the perineal muscles without involvement of the anal sphincter
Third degree

previous structures with involvement of the external anal sphincter → can cause fecal incontinence due to sphincter involvement

Fourth degree previous structures and the anterior wall of the anal canal or rectum
  • Treatment
    • Surgical repair within 24 hours
    • Depending on the degree of severity, local, regional, or general anesthesia can be used.
    • Suturing the torn structures with subsequent digital-rectal examination to assess wound care
  • Complications
  • Prevention: application of warm compress to perineum during delivery and avoidance of risk factors

Complications of fourth degree tears include rectovaginal fistulae!

Obstetric nerve injuries

Acute nerve injury can occur during childbirth due to compression, transection, traction, or vascular injury to the nerve.

Obstetric nerve injuries
Nerve Clinical Features Risk Factors
Lumbar radiculopathy
  • Lower back pain
  • Foot drop (↓ foot dorsiflexion and patellar reflex)
  • Paresthesia from the distal lateral thigh area over the patella up to the inner side of the lower leg
Lateral femoral cutaneous nerve injury
  • Pain and paresthesias on the anterolateral surface of the thigh
  • Maternal obesity
  • Prolonged semi-Fowler lithotomy position (bearing down with hip flexion, abduction, and external rotation)
  • A wide transverse c-section incision may transect the nerve.
  • Direct compression of the nerve with obstetric forceps
Common peroneal nerve injury
  • Paresthesias/decreased sensation of the dorsum of the foot and the anterolateral calf
  • Foot drop (↓ foot eversion and dorsiflexion), high-stepping gait
  • Prolonged squatting during childbirth
  • Hyperflexion of the knees during childbirth
  • Direct compression of the nerve with direct pressure over the fibular head
  • Inadequate foot rests or stirrups used during vaginal delivery

References:[15][43][44]

Umbilical cord complications

Umbilical cord compression (cord presentation)

Umbilical cord prolapse

Knotting of the umbilical cord

  • Most often caused by activity/turning of the fetus
  • Single cord around the neck: observed in ∼ 20% births
  • Multiple cord loops around the neck: < 1% births
  • Cord knot: 1–2% births

References:[5][45][46]