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Safe Prevention of the Primary Cesarean Delivery


Compared to vaginal delivery, cesarean delivery has greater risk of maternal severe morbidity and mortality. The international healthcare community has defined an ideal prevalence of cesarean delivery to be between 10% to 15%. Currently in the United States, one in three women give birth by cesarean delivery.

Several approaches have been used to decrease the prevalence of cesarean delivery. One of the main strategies includes the prevention of primary cesarean delivery, which decreases long-term risks and lowers the repeat cesarean delivery rate.  ACOG summarizes recommendations to safely avoid the first cesarean section.

Most common indications for cesarean delivery (starting with most frequent) include

  • Labor dystocia
  • Abnormal or indeterminate fetal heart rate tracing
  • Fetal malpresentation
  • Multiple gestation
  • Suspected fetal macrosomia

Dystocia in the First Stage of Labor

  • Consortium on Safe Labor: Contemporary labor data in the United States  
  • In a multi-center retrospective study, Zhang et al. reviewed the data of more than 60,000 normal deliveries from 2002 to 2008, constructing average labor curves showing that
    • Cervical dilation was slower until 6cm | Previously 4cm as described by Friedman
    • Time to progress from 4 to 10 cm was significantly higher than previously described

Latent phase

  • Latent phase, defined as prior to 6 cm, is no longer a criterion for cesarean section
  • Augmentation is recommended
    • Most patients will experience active labor spontaneously or after intervention (amniotomy and or oxytocin)
  • Allowing for longer duration of latent phase may avoid cesarean sections for failed induction, defined as rupture of membranes and oxytocin for 12 to 18 hours without cervical change

ACOG states that

Because they are contemporary and robust, it seems that the Consortium on Safe Labor data, rather than the standards proposed by Friedman, should inform evidence-based labor management

Active phase

  • Dilation of at least 6 cm should be considered the threshold for active phase
  • Cesarean delivery for arrest of dilation should be reserved for patients with the following criteria
    • ≥6 cm dilated with ruptured membranes and
      • ≥4 hours of adequate uterine contractions and no cervical change or
      •  ≥6 hours of oxytocin without adequate uterine activity and no cervical change

Note: There is an association between duration of first stage of labor and chorioamnionitis, but causality is unclear

Dystocia in the Second Stage of Labor

  • Longer duration of second stage of labor may be associated with adverse neonatal outcomes but risk appears to be low and incremental
  • Arrest of labor in the second stage diagnosis: No descent while pushing for 2 hours in multiparous and 3 hours in nulliparous patients without epidural anesthesia
    • Individualizing care and allowing for longer durations in certain patients who have received an epidural may be appropriate
  • Operative vaginal delivery
    • Safe alternative to cesarean when performed by skilled physicians
    • Encourage training, and ongoing maintenance, of practical skills
  • Manual rotation of the fetal occiput
    • Reduces cesarean rates whether successful or attempted
  • Frequently assess fetal position in second stage of labor, especially if there is abnormal fetal descent

Abnormal or Indeterminate Fetal Heart Rate Tracings 

Category III

  • Category III tracings are associated with fetal acidemia, cerebral palsy and encephalopathy and require expedient intervention
  • If intrauterine resuscitation (eg. repositioning, stopping oxytocin, assessment of hypotension) fails to improve the tracing, deliver rapidly and safely

Category II

  • Category II is common and comprises a diverse spectrum of patterns
    • Minimal variability, prolonged decelerations or recurrent late decelerations require intervention
  • Initiate intrauterine resuscitation with evaluation for other causes such as umbilical cord prolapse
  • Recurrent variable decelerations are not themselves pathologic but may lead to fetal acidemia
  • Scalp stimulation may help assess fetal acid-base status in presence of abnormal or indeterminate tracing

Note: Use of an algorithm, such as the Shields algorithm or Clark algorithm, may help guide management of Category II tracings (see ‘Primary Sources – Learn More’ below)

Fetal Malpresentation

  • Assess presentation beginning at 36w0d
  • External cephalic version (ECV) should be offered whenever possible at term | Success may be enhanced by terbutaline and regional anesthesia
  • One study showed an increased rate of successful ECV in patients that received regional anesthesia than ones that did not (79% success with anesthesia vs 56% success without)
  • The combination of anesthesia and tocolysis is associated with increased rates of success ECV, cephalic presentation in labor, and vaginal delivery

Twin Gestation 

  • Perinatal outcomes are not improved by cesarean if the first twin is in cephalic
  • Cephalic/cephalic or cephalic/non-cephalic should be counseled to attempt vaginal delivery
  • Residents should be trained to perform twin deliveries and second breech extraction

Suspected Fetal Macrosomia 

  • Limit cesarean delivery to
    • Without diabetes: Estimated fetal weight ≥5000 grams
    • With diabetes: Estimated fetal weight ≥4500 grams
  • Third trimester ultrasonography fetal weight estimate should be used sparingly and with clear indications
    • Patients should be counseled that the ultrasound estimation of fetal weight in late gestation is inaccurate
    • Weights ≥5000 grams are rare

Clinical Scenarios that May Prevent Avoidable Cesarean Delivery 

Elective Induction of Labor at 39 weeks

  • The ARRIVE trial was an RCT comparing elective induction at 39 weeks with expectant management in low-risk nulliparous patients
  • Primary fetal outcome: No statistical difference in perinatal mortality and severe morbidity
  • Pre-specified major maternal outcome
    • Cesarean delivery rate was significantly lower in the induction of labor group (18.6% versus 22.2%)

Note: Allow 24 h or more in the latent phase before diagnosing failed induction | Rupture of membranes and oxytocin for 12 to 18 hours must be present prior to diagnosis of failed induction

Excessive Maternal Weight Gain

  • Optimal weight gain during pregnancy varies by pre-pregnancy BMI
    • BMI <18.5: Weight gain between 18 to 40 lbs
    • BMI 18.5 to 24.9: Weight gain between 25 to 35 lbs
    • BMI 25.0 to 29.9: Weight gain between 15 to 25 lbs
    • BMI >30: Weight gain between 11 to 20 lbs
  • Weight gain above the recommended limits is associated with increased rates of cesarean delivery and adverse outcomes
  • Counseling about appropriate weight gain, diet and exercise is appropriate throughout pregnancy to prevent excessive weight gain

Herpes Simplex Virus

  • Recommendation is for prevention of outbreaks at time of delivery in women with history of genital herpes
  • Oral antiviral should be initiated within 3 to 4 weeks of delivery, at the latest starting at 36 weeks

Organizational level interventions

  • Changing local culture and attitudes using multifaceted interventions
    • Provider audits
    • Feedback or huddles
    • Second opinions
  • Continuous labor and delivery support | One-on-one support (such as doula) improves patient satisfaction and reduces the rate of cesarean delivery
  • Medico-legal pressures, tort reform
  • Provide better knowledge base for clinical decisions


  • Prolonged duration of latent phase of labor is not an indication for cesarean delivery
  • Cervical dilation of 6 cm should be the threshold for active phase of labor
  • Arrest of active phase of labor is defined as failure to progress after ruptured membranes and 4 hours of adequate or 6 hours of inadequate uterine activity
  • Arrest of second stage should be at least 2 hours in multiparous and 3 hours in nulliparous | Longer durations may be appropriate with regional anesthesia
  • Not all fetal heart rate tracing abnormalities are an indication for cesarean
  • Encourage operative delivery procedures when appropriate can help prevent cesarean delivery
  • Access to nonmedical interventions and changes in organizational level may reduce cesarean delivery rates

Primary Sources – Learn More: 

First and Second Stage Labor Management

ACOG Practice Bulletin 221: External Cephalic Version

ACOG Practice Bulletin 219: Operative Vaginal Birth

CMQCC: Addendum Toolkit to Support Vaginal Birth and Reduce Primary Cesareans

A Standardized Approach for Category II Fetal Heart Rate with Significant Decelerations: Maternal and Neonatal Outcomes (Shields)

Intrapartum Management of Category II Fetal Heart Rate Tracings: Towards Standardization of Care (Clark)

Induction of Labor: Indications and Management

Bishop Score Calculator


The purpose of induction of labor is to stimulate uterine contractions before onset of spontaneous labor for vaginal delivery.  The rates of induction of labor have significantly increased during the last decades. In 1990, less than 10% of pregnancies underwent induction of labor, vs 30% by 2019.  Currently, induction of labor is one of the most frequently performed obstetric procedures. A recent RCT comparing elective induction of labor at 39 weeks gestation with expectant management in nulliparous people (the ARRIVE trial – see below in ‘Related ObG Topics’), showed no increase in perinatal morbidity and mortality rates with lower rates of cesarean delivery. These results may lead to an increase in induction rates in the near future.


Indications include but are not limited to the following

  • Maternal conditions
    • Antepartum: Abruptio placentae | Chorioamnionitis | Fetal demise | Gestational hypertension | Preeclampsia | Eclampsia | PROM | Postterm pregnancy
    • Pregestational: Diabetes mellitus | Renal disease | Chronic pulmonary disease | Chronic hypertension | Antiphospholipid syndrome
  • Fetal compromise
    • Fetal growth restriction | Isoimmunization | Oligohydramnios
  • Logistical reasons >39 weeks
    • Risk of rapid labor | Distance to hospital | Psychosocial indications

Note: See summary of guidance on timing of delivery for medical indications below in ‘Related ObG Topics’


  • Similar to contraindications for vaginal delivery
    • Vasa previa or complete placenta previa
    • Transverse fetal lie
    • Umbilical cord prolapse
    • Previous classical cesarean delivery
    • Active genital herpes infection
    • Previous myomectomy entering endometrial cavity

Cervical Preparation

Bishop Score

  • A Bishop score of ≤6 is associated with low rate of successful induction with oxytocin alone, and the use of cervical ripening agents are recommended

Cervical Ripening Agents

  • Misoprostol (PGE1 analogue) given intravaginally, orally or sublingually
    • Initial dose: 25 mcg every 3 to 6 hours
    • Delay oxytocin 4 hours after last dose
    • Available evidence supports safety and efficacy
    • Higher rates of tachysystole
      • When compared to PGE2
      • With dosing ≥50 mcg
    • Contraindications: Prior cesarean and/or uterine surgery due to risk for uterine rupture
  • Dinoprostone (PGE2 preparations) given vaginally via gel or insert
    • 0.5 mg in 2.5 ml syringe gel or 10 mg vaginal insert
    • Second dose after 6 to 12 h (maximum dose of 1.5 mg in 24 hours)
    • Delay oxytocin 6 to 12 hours after last application of gel or 30 to 60 min after insert

Note: After prostaglandin use (misoprostol or dinoprostone), patient should remain recumbent for at least 30 minutes | Fetal heart tracing should be monitored continuously for 30 minutes to 2 hours | FHR monitoring should be continued if regular uterine contractions are persistent

  • Mechanical dilators
    • Foley catheter ( 30 to 80 ml): Reasonable and effective option for cervical ripening
    • Double balloon device
    • Others dilator options: Hygroscopic dilation | Osmotic dilators (Laminaria japonicum) | Extra amniotic saline infusion

Methods of Induction 


  • Pitocin is synthetic formulation for oxytocin, with both low-dose and high-dose regimens
    • Low-dose regimen: 0.5 to 2 mU with increasing rate of 1 to 2 mU/min every 15 to 40 minutes
    • High-dose regimen: 6 mU with increasing rate of 3 to 6 mU/min every 15 to 40 minutes
  • High-dose regimen:
    • Shorter labor | Less chorioamnionitis | Less cesarean
    • More tachysystole with FHR changes
  • Myometrium becomes more sensitive to oxytocin increases with advancing gestation
  • Management of tachysystole with FHR changes
    • Decrease/discontinue oxytocin
    • Corrective measures: Turn patient on side | Oxygen | Fluids | Terbutaline

Membrane Stripping

  • Mechanical technique
    • Insertion of one or two fingers into the cervix | Continuous circular sweeping motion detaches the inferior pole of the membranes from the lower uterine segment
  • Reduces rates of formal induction (2.3% vs 3.1%) and increases rates of spontaneous labor (72% vs 60%)
  • Positive GBS – insufficient data for recommendation


  • Better when cervix is favorable
  • In combination with oxytocin: Reduces interval from induction to delivery by approximately 5 hours
  • Risks: Cord prolapse | Chorioamnionitis
  • Avoid, if possible: HIV, hepatitis B or hepatitis C
  • Positive GBS: No data to suggest increased risk for neonatal disease when appropriate intrapartum antibiotic prophylaxis is given

Nipple Stimulation

  • Increase likelihood of labor when cervix is favorable
  • Only studied in low-risk populations
  • In meta-analysis
    • Decrease in women not in labor after 72 hours
    • Decrease in PPH
    • No impact on meconium-stained amniotic fluid or cesarean delivery
    • Due to association with an increased trend toward association with perinatal death “this practice is not recommended in an unmonitored setting”

Specific Clinical Scenarios 

Ruptured Membranes

  • Induction with oxytocin is associated with decreased
    • Interval between PROM and delivery
    • Frequency of chorioamnionitis
    • Postpartum febrile morbidity
  • Prostaglandins appear safe and effective

Intrauterine Fetal Demise

  • <28 weeks
    • Misoprostol 200 to 400 mcg vaginally every 4 to 12 hours
  • >28 weeks
    • Standard obstetric protocol for labor induction
  • Prior uterine scar
    • <28 weeks: 400 mcg vaginally every 6 hours | “does not appear to be an increase in complications”
    • >28 weeks: Foley for cervical ripening
    • Trial of labor is reasonable if prior low transverse cesarean delivery
  • Prior classical incision
    • Limited data to guide clinical practice


  • Prior to starting an induction of labor, contraindications should be reviewed
  • Cervical ripening is recommended with a Bishop score of ≤6
  • Predictors of induction success
    • Lower BMI | Greater dilation | Higher parity | Term gestational age
  • Pharmacologic and non-pharmacologic methods can be used for induction based on the patient’s characteristics
  • Misoprostol regimens are recommended for intrauterine fetal demise including TOLAC
  • There is no strong consensus to define failed induction
    • At least 12 to 18 hours of latent labor with oxytocin and AROM should be allowed before diagnosing failed induction

Learn More – Primary Sources:

ACOG Practice Bulletin 107: Induction of Labor

The ARRIVE Trial and Professional Guidance: Elective 39 Week Induction to Reduce the Risk of Cesarean Section


The ARRIVE study (A Randomized Trial of Induction Versus Expectant Management), authored by Grobman et al. (NEJM, 2018), was undertaken to determine if elective induction of labor (IOL) of low-risk nulliparous women at 39 weeks reduces adverse perinatal and neonatal morbidity compared to expectant management. SMFM released a statement, endorsed by ACOG, addressing the ARRIVE findings.

SMFM Recommendations

It is reasonable to offer elective IOL to low-risk, nulliparous women at or beyond 39 weeks and 0 days of gestation. We recommend that providers who choose this approach ensure that women meet eligibility criteria of the ARRIVE trial.

We recommend against offering elective IOL to women under circumstances that are inconsistent with the ARRIVE study protocol unless performed as part of research or quality improvement.

We recommend that further research be conducted to measure the impact of this practice in settings other than a clinical trial.

Study Highlights 


    • Multicenter, randomized, controlled, parallel-group, unmasked trial
        • Low-risk nulliparous women between 34w0d-38w6d
        • Live singleton, vertex fetus
        • No contraindications to vaginal delivery
      • No planned cesarean deliver
    • Low-risk
      • No maternal or fetal condition that would be an indication for delivery <40w5d
    • Randomization
        • Induction group: IOL at 39w0d-39w4d
      • Expectant group: No elective delivery <40w5d and begin delivery no later than 42w2d
    • Primary outcome
      • Composite of perinatal death or severe neonatal complications
  • Secondary outcomes
    • Multiple neonatal and maternal outcomes including mode of delivery


    • 3,062 women labor induction group | 3,044 expectant management group
    • Primary outcome not statistically different
      • 4.3% of neonates in induction group vs 5.4% in the expectant group
      • Relative risk (RR) 0.80; 95% CI, 0.64-1.00 (P=0.049)
        • To account for an interim analysis, a two-tailed P value of <0.046 was used for statistical significance threshold
    • Cesarean delivery was less frequent in the induced labor group (19%) vs the expectant management group (22%) 
      • RR 0.84; 95% CI 0.76-0.93
    • Preeclampsia and gestational hypertension occurred in 9.1% of the induced group vs 14.1% of the expectant management group 
      • RR 0.64; 95% CI 0.56-0.74
  • Among newborns, 3% in the induced group needed respiratory support vs 4.2% in the expectant management group
    • RR 0.71; 95% CI 0.55-0.93


  • There was no difference between groups with respect to composite adverse perinatal outcome, but there was reduced frequency of cesarean section in the induction group
  • There was increased incidence of maternal hypertension/preeclampsia and newborn respiratory support in the expectant management group
  • The authors state

Our data suggest that 1 cesarean delivery may be avoided for every 28 deliveries among low-risk nulliparous women who plan to undergo elective induction of labor at 39 weeks.


Induction Protocol Highlights

  • Patients had a cervical exam between 72 hours prior to randomization and 24 hours after randomization
  • IOL protocol
    • Induction using oxytocin
    • Unfavorable cervix (modified Bishop score <5) underwent cervical ripening
      • method left to patient’s physician’s discretion
      • with or followed by oxytocin stimulation
  • ‘Failed’ Labor in latent phase
    • At least 12 hours after completion of cervical ripening, rupture of membranes, and use of a uterine stimulant
    • Cesarean decision left to patient’s physician’s discretion
  • Additional SMFM recommendations
    • Shared decision making is ‘critical’
    • All women in this study had ultrasound dating, early in pregnancy
      • Certain LMP: <21 weeks
      • Uncertain LMP: First trimester ultrasound
  • ACOG has also released a Practice Advisory related to ARRIVE (see ‘Learn More-Primary Sources’ below) that also highlights the importance of shared decision making as well as taking in to account “resources available (including personnel), and the setting in which the intervention will be implemented”

Learn More – Primary Sources:

Labor Induction versus Expectant Management in Low-Risk Nulliparous Women

SMFM Statement: Elective induction of labor in low-risk nulliparous women at term: The ARRIVE trial

ACOG Practice Advisory: Clinical guidance for integration of the findings of The ARRIVE Trial: Labor Induction versus Expectant Management in Low-Risk Nulliparous Women