Childbirth

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 delivery may be indicated under certain circumstances.

Obstetric contractions (uterine muscle contractions) ^[1][2][3]

False labor only requires reassurance.

Stages of labor ^[1][2][3]

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 )

Overview of abnormal labor

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

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.

Rupture of membranes (ROM) is the rupture of the amniotic sac followed by the release of the amniotic fluid and typically occurs spontaneously during the first stage of labor, signifying the onset of labor. Delayed ROM occurs during, rather than before, fetal expulsion, after cervical dilation and effacement. ROM that occurs prior to the onset of labor in term and preterm pregnancies is discussed below.

Types

Premature rupture of membranes (PROM)

• Definition: rupture of membranes occurring before onset of labor at term
• Epidemiology: between 5 and 10% of all deliveries
• Risk factors
  • Ascending infection (common)
  • Cigarette smoking
  • Multiple pregnancy
  • Previous preterm delivery
  • Previous PROM
• Complications ^[12]
  • Umbilical cord prolapse or injury
  • Placental abruption
  • Chorioamnionitis, possibly leading to:
    • Premature labor/ preterm birth
    • Fetal distress → perinatal death
    • Sepsis
  • Pulmonary hypertension, pulmonary hypoplasia, ARDS (newborn)
  • Postpartum infection
  • Endometritis

Preterm premature rupture of membranes (PPROM)

• Definition: : rupture of membranes before onset of uterine contractions AND before 37 weeks' gestation
• Epidemiology: occurs in 2–5 % of pregnancies
• Risk factors: previous PPROM, in addition to PROM risk factors
• Complications: see complications of PROM

Prolonged rupture of membranes

• Definition: ROM that occurs > 18 hours before the onset of uterine contractions in term or preterm pregnancies
• Risk factors: young maternal age, smoking, STDs, low socioeconomic status

Clinical features

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

Diagnostics

• 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.
    • Positive placental α-microglobulin-1 (PAMG-1) in cervicovaginal fluid
• Ultrasound: oligohydramnios may be present
• Fetal heart rate monitoring: assess for nonreassuring fetal status
• Maternal examination assess for signs of infection (body temperature, uterine tenderness, WBC count)

Management ^[13]

The management of PROM and PPROM depends on the gestational age and the presence of intraamniotic infection or nonreassuring fetal status.

• In all cases
  • Monitor patients for signs of intraamniotic infection.
  • Perform fetal heart rate monitoring.
  • Consider intrapartum risk factors and GBS screening and prophylaxis, depending on whether previous antenatal GBS screening has been performed.

Unstable patients

• Prompt delivery in:
  • Patients with signs of intraamniotic infection, abruptio placentae, cord prolapse
  • Signs of fetal distress (nonreassuring fetal heart rate)
• Additionally, collect cervical cultures and commence empiric antibiotic therapy ampicillin and gentamicin.

Stable patients

• Gestational age: ≥ 37 0/7 weeks (term)
  • Delivery by induction of labor is generally recommended.
  • Expectant management for up to 12–24 hours is reasonable in otherwise uncomplicated pregnancies and in the absence of infection.
• Gestational age: 34 0/7–36 6/7 weeks (late-preterm)
  • Expectant management and induction of labor are both reasonable options.
  • Expectant management
    • Bed rest, pelvic rest
    • Induction of fetal lung maturity: single-course of antenatal corticosteroids if not previously given if there is no evidence of chorioamnionitis and delivery is anticipated in > 24 hours and < 7 days
• Gestational age: 24 0/7–33 6/7 weeks
  • Expectant management
    • Bed rest, pelvic rest
    • Prophylactic antibiotics to reduce the risk of infection and delay delivery
      • Ampicillin IV PLUS erythromycin IV followed by amoxicillin PO PLUS erythromycin PO
        OR
      • Ampicillin IV PLUS azithromycin IV followed by amoxicillin PO PLUS azithromycin PO
    • Single-course of antenatal corticosteroids (betamethasone or dexamethasone)
    • Tocolysis; can be used to delay delivery for up to 48 hours so that antenatal corticosteroids can be administered. ^[14]
    • Magnesium sulfate; if preterm delivery < 32 weeks gestation is anticipated ^[15]
• Gestational age < 23–24 weeks
  • Fetal outcome is generally poor in PPROM before or at the limit of viability.
  • The choice of management depends on patient-specific factors and preference.
  • Expectant management
    • Not recommended before viability
    • Same approach as for pregnant women at 24 0/7–33 6/7 weeks

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

Electronic fetal heart rate monitoring ^[16][17]

• Description: widely used diagnostic tool during 3^rd trimester and labor 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 (bpm) 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 monitoring).
    • Rupture of the membranes must have occurred or an amniotomy performed
    • Used when external monitoring is difficult (e.g., maternal obesity, polyhydramnios, multiple gestations)
  • Mechanoelectrical measurement of uterine contractions via a pressure transducer, recording in the lower curve in kPa (tocodynagraph)
• Indications
  • During labor
  • Admission in the labor ward
  • In every case of complication during pregnancy or delivery, such as impending preterm birth, abnormalities of the fetal heart, multiple pregnancy, suspected placental insufficiency, uterine bleeding, tocolysis

Fetal heart rate ^[18][19][20]

• In CTG, the FHR is designated as the baseline or basal heart rate and is normally 110–160 bpm.
• Tachycardia
  • Mild tachycardia: FHR of 160–180 bpm for > 10 minutes
  • Severe tachycardia: FHR of ≥180 bpm for > 10 minutes
  • Causes: stress, hypotension, maternal fever; , medication (e.g., betamimetics for the treatment of tocolysis), chorioamnionitis, fetal arrhythmias, fetal anemia, hypoxia
• Bradycardia
  • Mild bradycardia: FHR of < 110 bpm for > 3 minutes
  • Severe bradycardia: FHR of < 100 bpm for > 3 minutes
  • Causes: supine hypotensive syndrome, fetal heart defects; , central nervous system anomalies, severe hypoxia
• Methods to assess FHR: Nonstress test (NST) and contraction stress test (CST); are performed during the third trimester of pregnancy to measure FHR reactivity to fetal movements and FHR reactivity in response to uterine contractions respectively. See nonstress test and contraction stress test in “Prenatal care” for details.

Fetal heart rate variability ^[21]

• On CTG, variability of FHR is represented by the oscillation of the FHR around the baseline and is determined by measuring the amplitude between the highest and lowest turning point of the FHR curve.

Acceleration (CTG) ^[20]

• Description: a normal temporal increase in the FHR from the baseline by > 15 bpm for more than 15 seconds but less than 10 minutes if the gestational age is > 32 weeks, or by > 10 bpm for more than 10 seconds if the gestational age is < 32 weeks
• Interpretation
  • The presence of > 2 accelerations within a span of 20 minutes indicates a reactive fetal heart rate tracing.
  • If the acceleration lasts longer than 10 minutes, it should be considered a baseline change in the fetal heart rate.

Decelerations (CTG) ^{[16][22][23][24][25]}

• Description: a temporary decline in the FHR of > 15 bpm for a maximum duration of 3 minutes

Interpretation and management

Interpretation

• Nonreassuring fetal status
  • Characteristic changes in the fetal heart rate (FHR) in response to fetal hypoxia and metabolic acidosis
    • Fetal tachycardia (FHR > 160–180/min)
    • Fetal bradycardia (FHR < 110/min)
    • Loss of baseline variability
    • Recurrent variable decelerations and/or late decelerations
  • A nonreassuring tracing requires intrauterine resuscitation and/or immediate delivery (cesarean or, if imminent, vaginal delivery).
• Reassuring fetal status
  • A fetal heart tracing that shows a good beat to beat variability (> 6 bpm), > 2 accelerations within a 20 minute period, and no evidence of fetal distress (e.g., fetal bradycardia, fetal tachycardia, late or variable decelerations, sinusoidal pattern)
  • Indicates fetal well-being.

Management with intrauterine resuscitation measures ^[18][19][26]

• Repositioning of the mother, administer O2 and possibly fluids
  • Positions that reduce cord compression: lying on the right or left side, on hands and knees, Trendelenburg position, lateral semi-Fowler's position
  • Manual elevation of the fetal head (fetus is pushed back into the uterus)
  • Consider filling the bladder with saline
• If initial steps unsuccessful, consider:
  • Amnioinfusion: instillation of saline into the amniotic cavity after artificial rupture of membranes
  • If uterine tachysystole is present (> 5 contractions in a period of 10 minutes): reduce uterine activity by giving tocolytics
  • Emergency cesarean delivery
• Delay active pushing during the 2^nd phase of labor

Indications

• Post-term pregnancy (≥ 42 weeks of pregnancy or gestation)
• Preterm premature rupture of membranes after 34 weeks
• Premature rupture of membranes at term
• Hypertension during pregnancy, preeclampsia, eclampsia, HELLP syndrome
• Maternal diabetes to avoid post-term pregnancy (risk of macrosomia)
• Maternal request at term
• Intrauterine death

Contraindications

• History of uterine rupture; previous high-risk cesarean delivery
• Placenta previa
• Vasa previa
• Transverse fetal lie
• Cord prolapse
• Active maternal genital herpes
• Nonreassuring fetal heart rate

Modified Bishop score

• Used to assess the cervix and the likelihood of a successful induction
• Interpretation
  • Bishop score ≥ 8: favorable cervix for vaginal delivery
  • Bishop score ≤ 6: unripe or unfavorable cervix; not ready for vaginal delivery
  • Simplified Bishop score
    • Considers only fetal station, cervical dilation, and cervical effacement
    • A score ≥ 5 indicates a favorable cervix for vaginal delivery.

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.

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
  • Prolonged second stage of labor
  • Breech presentation
  • Nonreassuring fetal heart rate
  • To avoid/assist maternal pushing efforts (.g., maternal fatigue or cardiopulmonary conditions)
• 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
  • Maternal: obstetric lacerations (cervix, vagina, uterus), perineal hematomas, urinary tract injury, anal sphincter injury
  • Fetal: head or soft tissue trauma (e.g., scalp lacerations, injured ears), facial nerve palsy, intracranial hemorrhage, retinal hemorrhage, skull fractures, fetal death (rare)

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
  • Prolonged second stage of labor
  • Nonreassuring fetal heart rate
  • To avoid/assist maternal pushing efforts
• 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 delivery.

References:^[5]

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
  • Postoperative complications
  • Long recovery period

Indications

There are guidelines detailing indications for cesarean delivery 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.

Cesarean delivery on maternal request (“on-demand”)

• Overview
  • Primary cesarean delivery that is performed on the mother's request in the absence of medical indications
  • Medically and ethically acceptable if the patient is well-informed
  • Possible reasons include:
    • Fear of the pain of labor
    • Prior negative labor experience
    • Possibility of scheduled delivery
    • Concerns about fetal harm during vaginal birth
  • Physicians are not obliged to perform a non-medically indicated cesarean delivery and may refer the patient to another obstetrician willing to perform the procedure.
• Approach
  • Explore the reasons behind the request
  • Address concerns about labor and provide information about prenatal childbirth education, obstetric analgesia, and emotional support during labor
  • Lead a balanced discussion about the risks and benefits of cesarean delivery and vaginal birth
  • If the patient insists on having a cesarean delivery, schedule the procedure for after 39 weeks of gestation

Types

Procedure

• 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

Complications

• Maternal
  • Hemorrhage
  • Thromboembolic events
  • Surgical injury (i.e., to the bowel, bladder)
  • Infections (i.e., of the endometrium, pelvis, lungs, urinary tract)
  • Impaired uterine regression
  • Higher risk of complications in subsequent pregnancies (e.g., abnormal placental attachment, uterine rupture)
• Fetal: risk of postnatal transient tachypnea of the newborn and respiratory distress syndrome

There are guidelines detailing indications for cesarean delivery 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.

Perineal lacerations

• Definition: tear of the perineal area due to significant or rapid stretching forces during labor and delivery
• Epidemiology: most common obstetric injury of the pelvic floor
• Risk factors ^[28]
  • Macrosomia
  • Forceps delivery
  • No previous delivery
  • Prolonged second stage of labor
  • Occiput posterior delivery
  • Rapid delivery of head in breech presentation
  • Head extension before crowning
  • Lack of perineal elasticity (e.g., perineal edema)
• Classification ^[29]
  • First degree: cutaneous to subcutaneous tissue tear (skin, fourchette, posterior vaginal wall) with no involvement of the perineal muscles
  • Second degree: first-degree lacerations plus laceration of the perineal muscles without involvement of the anal sphincter
  • Third degree: second-degree lacerations plus involvement of the external anal sphincter; may lead to fecal incontinence due to sphincter involvement
  • Fourth degree: third-degree lacerations plus lacerations of the anterior wall of the anal canal or rectum
• Treatment: surgical repair within 24 hours
  • First and second degree: local anesthesia and laceration closure using continuous sutures
  • Third and fourth degree
    • Regional or general anesthesia can be used
    • Reconstructive surgery to repair the anal sphincters and mucosa
    • Reconstruction of the distal rectovaginal septum and the perineal body
• Complications
  • Wound dehiscence
  • Infection
  • Hemorrhage
  • Rectovaginal fistulae
  • Pain and dyspareunia
• Prevention: application of warm compress to perineum during delivery

Complications of fourth-degree lacerations include rectovaginal fistulae.

Obstetric nerve injuries ^[30]

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

Causes

• Most common: Umbilical cord prolapse
• Uterine contractions during childbirth
• Nuchal cord (wrapping of the umbilical cord)
• Knotting of the umbilical cord
• Entanglement of the umbilical cord

Umbilical cord prolapse

There are 3 types:

• Overt umbilical cord prolapse
• Occult umbilical cord prolapse
• Cord presentation

Overt umbilical cord prolapse

• Definition: Condition in which a part of the umbilical cord lies between the antecedent part of the fetus (mostly head) and the pelvic wall, causing rupture of membranes and acute, life-threatening hypoxia for the fetus.
• Epidemiology: Most common form of cord prolapse (0.5% births)
• Etiology: often seen in presentation anomalies (e.g., breech presentation, transverse fetal position), multiple pregnancy, long umbilical cord, or abnormal fetal movement (polyhydramnios, premature birth)
• Clinical features: an abrupt change from a previously normal CTG to one with fetal bradycardia or recurrent, severe decelerations, occuring after the rupture of membranes
• Diagnostics: thick, pulsating cord is palpable on vaginal examination
• Management: See “Treatment with intrauterine resuscitation measures” in “Intrapartum fetal monitoring” above

Occult umbilical cord prolapse

• Similar to overt umbilical cord prolapse, but the umbilical cord has not advanced past the presenting fetal part.

Cord presentation

• Definition: part of the umbilical cord lies between the antecedent part of the fetus (mostly head) and the pelvic wall; the amniotic sac is intact
• Etiology: oligohydramnios, presentation abnormalities
• Clinical features: recurrent variable decelerations on cardiotocography ; may progress to umbilical cord prolapses if membranes rupture
• Diagnostics: clinical diagnosis
• Treatment
  • See “Treatment with intrauterine resuscitation measures” in “Intrapartum fetal monitoring” above.
  • Often, spontaneous reduction of the umbilical cord into the uterus if the mother is placed in a different position (e.g., Trendelenburg position ) enables vaginal birth.

Nuchal cord ^[5]

• 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

Knotting of the umbilical cord

• Most often caused by activity/turning of the fetus
• Cord knot: 1–2% births

• Statistics
  • In the US, approx. 1% of births per year are home births.
  • 75% of these home births are planned.
• Indications
  • There is insufficient evidence to determine what makes a good candidate for a home birth.
  • Home births can be considered in individuals with no contraindications.
  • Patients who would like to plan a home birth should be advised about the benefits and risks of home birth compared to hospital delivery in order to make an informed decision.
• Advantages compared to hospital delivery
  • Lower risk of maternal interventions (e.g., induction or augmentation of labor, episiotomy, cesarean delivery)
  • Lower risk of certain maternal complications (e.g., vaginal or perineal lacerations, peripartum or postpartum infections)
  • Lower costs
  • Familiar environment for the mother
• Disadvantages compared to hospital delivery
  • Higher risk of perinatal death for both the mother and fetus
  • Higher risk of neurological complications for the newborn
• Contraindications
  • Absolute contraindications
    • Fetal malpresentation (e.g., breech presentation)
    • Multiple gestation pregnancy
    • Previous cesarean delivery
  • Relative contraindications
    • Any other risk factor for a complicated pregnancy (see “High-risk pregnancies”)
    • No means for safe and timely transport to a nearby hospital or accredited birth center
    • Lack of access to home-birth provider services (e.g., certified professional midwife, certified nurse midwife, obstetrician, family medicine physician)

References:^[31][32]