VOLUME 42 • NUMBER 13
TOPICS IN
September 15, 2022
OBSTETRICS & GYNECOLOGY
Practical CE Newsletter for Clinicians
Best Practices: Induction of Labor
Amber Young, MD, and Dayna Burrell, MD
Learning Objectives: After participating in this continuing professional development activity, the provider should be
better able to:
1. Identify indications for and contraindications to induction of labor.
2. Describe methods used for induction of labor, including medications and procedures.
3. Explain best practices for induction of labor in patients with special circumstances.
4. Define failed induction of labor.
Key Words: Delivery, Induction, Labor
induction of labor with indications to consider an alternative
timing or approach to delivery.
Induction of labor is defined as the process of stimulating
uterine contractions before the onset of labor with the goal
of achieving a vaginal delivery.1 In 2020, over 31% of
gravid patients in the United States underwent induction of
labor, and this number has steadily increased over the past
10 years.2 Induction of labor is generally recommended
when the benefits of delivery outweigh the risks of remaining pregnant.1 Given the growing number of patients undergoing induction of labor on a yearly basis, our aim is to
review best practices for this process. We identify indications for and contraindications to induction of labor, summarize applicable medical and procedural methods, and
consider special circumstances for patients undergoing
induction, including those with a history of cesarean delivery, current intrauterine fetal demise (IUFD), or personal
history of trauma. Lastly, we outline definitions of failed
Indications
Induction of labor is indicated for many different maternal and fetal conditions, and may also be planned without
underlying medical comorbidities for psychosocial indications, risk of precipitous delivery, or as an elective process.
In each of these clinical scenarios, it is essential to weigh
the maternal and neonatal risk of delivery with the risks of
continuing pregnancy.
A prerequisite to scheduling an induction of labor is to
confirm the patient’s estimated due date (EDD). Last menstrual period (LMP) should be documented, and calculated
EDD should ideally be concordant with dating by ultrasound. Ultrasound measurement in the first trimester is the
most reliable method to establish an accurate gestational
age and EDD, and should be used independently if LMP is
unknown. If LMP and first-trimester ultrasound are unavailable, dating should be estimated by second or third-trimester ultrasound as available, but should be considered suboptimal, and taken into account when considering induction.
Dr. Young is a Resident, and Dr. Burrell is Assistant Professor, Department of
Obstetrics and Gynecology, Women & Infants Hospital of Rhode Island, 101
Dudley St, Providence, RI 02905; E-mail: abyoung@wihri.org.
All authors, faculty, and staff have no relevant financial relationship with any
ineligible organizations regarding this educational activity.
CME Accreditation
Lippincott Continuing Medical Education Institute, Inc., is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical
education for physicians.
Lippincott Continuing Medical Education Institute, Inc., designates this enduring material for a maximum of 2.0 AMA PRA Category 1 Credits™. Physicians should
claim only the credit commensurate with the extent of their participation in the activity. To earn CME credit, you must read the CME article and complete the quiz and
evaluation on the enclosed answer form, answering at least seven of the 10 quiz questions correctly. This CME activity expires on September 14, 2024.
NCPD Accreditation
Lippincott Professional Development is accredited as a provider of nursing continuing professional development (NCPD) by the American Nurses Credentialing
Center’s Commission on Accreditation. Lippincott Professional Development will award 2.0 contact hours for this NCPD activity. This activity has been assigned
1.0 pharmacology credits. This activity is also provider approved by the California Board of Registered Nursing, Provider Number CEP 11749 for 2.0 contact hours.
Lippincott Professional Development is also an approved provider of continuing nursing education by the District of Columbia, Georgia, West Virginia, New
Mexico, South Carolina, and Florida, CE Broker #50-1223. Your certificate is valid in all states. Instructions for earning ANCC contact hours are included on page
11 of the newsletter. This NCPD activity expires on September 5, 2025.
1
Postgraduate Obstetrics & Gynecology
Editors
William Schlaff, MD
Professor and Chair,
Department of Obstetrics
and Gynecology, Thomas
Jefferson Medical College,
Philadelphia, Pennsylvania
Lorraine Dugoff, MD
Professor and Chief, Division of
Reproductive Genetics,
Department of Obstetrics
and Gynecology, University
of Pennsylvania Perelman
School of Medicine,
Philadelphia, Pennsylvania
Founding Editors
Edward E. Wallach, MD
Roger D. Kempers, MD
Associate Editors
Meredith Alston, MD
Denver, Colorado
Amanda V. French, MD
Boston, MA
Nancy D. Gaba, MD
Washington, DC
Veronica Gomez-Lobo, MD
Washington, DC
Star Hampton, MD
Providence, Rhode Island
Enrique Hernandez, MD
Philadelphia, Pennsylvania
Bradley S. Hurst, MD
Charlotte, North Carolina
Jeffrey A. Kuller, MD
Durham, North Carolina
Peter G. McGovern, MD
New York, New York
Owen Montgomery, MD
Philadelphia, Pennsylvania
Christopher M. Morosky, MD
Farmington, Connecticut
William D. Petok, PhD
Baltimore, Maryland
September 15, 2022
Pregnancies resulting from in vitro fertilization should utilize the date of transfer and
age of embryo to determine EDD.3
Recommendations for planned timing of
induction of labor depend upon the indication for induction. Induction of labor should
not be elected before 390/7 weeks of estimated gestational age (EGA) unless medically indicated.4
Common indications for induction and
suggested timing based on weeks of gestation are summarized in Table 1, adapted
from the American College of Obstetricians
& Gynecologists Committee Opinion on
Medically Indicated Late-preterm and
Early-Term Deliveries.5 Preterm is defined
as a pregnancy at less than 340/7 weeks of
EGA. Late preterm is defined as 340/7 to
366/7 weeks of EGA, whereas early term is
defined as 370/7 to 386/7 weeks of EGA. If
induction of labor is medically indicated
before 370/7 weeks of EGA, administration
of antenatal corticosteroids for fetal lung
maturity should be considered.5 Additional
defined time frames when induction may
also be indicated are full-term (390/7–406/7
weeks of EGA), late-term (410/7–416/7
weeks of EGA), and post-term pregnancies
(³420/7 weeks).6 Induction of labor in a lateterm pregnancy should be considered,
whereas induction in post-term pregnancies
is highly recommended due to a known
increase in perinatal morbidity with continued gestation beyond 420/7 weeks of EGA.7
Further recommendations to consider
induction of labor in patients at or beyond
390/7 weeks of EGA are actively evolving.
In 2018, the ARRIVE trial (A Randomized
Trial of Induction Versus Expectant
Management) sought to delineate maternal
and perinatal outcomes after induction of
labor at 39 weeks in low-risk nulliparous
women. This large multicenter study looked
primarily at rates of perinatal death or severe
neonatal complications in low-risk nulliparous women at 39 weeks 0 days to 39 weeks
4 days who underwent induction of labor
versus expectant management. The main
secondary outcome was the rate of cesarean
delivery in each arm. This study demonstrated that induction of labor in low-risk
nulliparous women did not result in a significantly lower frequency of adverse perinatal
outcomes but did result in significantly lower
rates of cesarean deliveries.8 Secondary analyses from this trial are anticipated, and further studies to evaluate the maternal and
perinatal outcomes of induction of labor in
expanded populations. Induction of labor in
patients at or beyond 390/7 weeks of EGA
can also be considered for psychosocial indications and in patients with a history of precipitous delivery with patient counseling and
shared decision-making.
Contraindications
Any condition which would preclude a
vaginal delivery would also be considered a
contraindication to induction of labor.
Examples can be considered in terms of
maternal, fetal, and placental complications
precluding vaginal birth, and are outlined in
Table 2. This is not a comprehensive list, but
includes more commonly encountered
diagnoses.1,9
Methods for Induction of Labor
Primary steps to begin an induction of
labor depend upon the cervical examination.
Providers can use the Bishop score (Table 3)
to determine whether a cervix is favorable or
unfavorable, with an unfavorable cervix
being defined as a score of 6 or less.10
The continuing professional development activity in Topics in Obstetrics & Gynecology is intended for obstetricians, gynecologists, advanced
practice nurses, and other health care professionals with an interest in the diagnosis and treatment of obstetric and gynecological conditions.
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2
September 15, 2022
Topics in Obstetrics & Gynecology
Table 1. Common Indications for Induction of Labor*
Indication for Induction
Table 2. Contraindications to Induction of Labor
Suggested Timing
Estimated Gestational
Age (EGA), wk
Maternal
Active genital herpes infection or prodromal symptoms
HIV with intact membranes and viral load >1000 copies/mL
Maternal conditions
History of >2 prior cesarean deliveries
Hypertensive disorders
380/7 – 396/7
Chronic (controlled, no medications)
370/7 – 396/7
History of classical incision or myomectomy with entry into the
endometrial cavity
Chronic (controlled, on medications)
360/7 – 376/7
History of uterine rupture
Chronic (uncontrolled)
370/7
Gestational hypertension or preeclampsia
without severe features
340/7
Preeclampsia with severe features
Malpresentation: transverse or oblique fetal lie
Umbilical cord prolapse
390/7 – 396/7
Diabetes
360/7 – 386/7
Pregestational (controlled)
390/7 – 406/7
Pregestational (uncontrolled/complicated)
390/7 – 396/7
Gestational (controlled, no medications)
Individualized plan
Gestational (controlled, on medications)
360/7 – 390/7
Gestational (uncontrolled)
Fetal
Placental
Placenta previa
Vasa previa
Placenta accreta spectrum
process of softening and thinning the cervix, which can
improve the effectiveness of oxytocin administered later in
the induction process.11 Cervical ripening can be accomplished by procedural approaches including membrane
sweeping or stripping and mechanical dilation and by
administration of prostaglandins.
360/7
Intrahepatic cholestasis of pregnancy
Total bile acids <100 μmol/L
Total bile acids ≥100 μmol/L
Fetal conditions
Oligohydramnios
360/7 – 376/7
Polyhydramnios
390/7 – 406/7
Membrane Sweeping
Fetal growth restriction (FGR)
380/7 – 390/7
Membrane sweeping or stripping is a process by which
the amnion is separated from the lower uterine segment by
sweeping the finger in a 360-degree fashion during a cervical digital examination. This procedure results in the release
of endogenous prostaglandins and phospholipase A from
the cervix and lower uterine segment, and can increase the
likelihood of spontaneous labor within 48 hours. Further
studies to determine the optimal timing and frequency of
membrane sweeping are indicated.12
Estimated fetal weight (EFW) 3rd-10th
percentile, uncomplicated
370/7
EFW <3rd percentile, uncomplicated
370/7
Umbilical artery (UA) Dopplers elevated
330/7 – 340/7
UA Dopplers: absent end-diastolic flow
300/7 – 320/7
UA Dopplers: reversed end-diastolic flow
340/7 – 376/7
FGR with concurrent comorbidities
380/7 – 386/7
Multiple gestations
Dichorionic-diamniotic twins
340/7 – 376/7
Monochorionic-diamniotic twins
320/7 – 340/7
Monochorionic-monoamniotic twins
Individualized
Triplets and higher-order multiples
At diagnosis
Mechanical Cervical Ripening
Proposed mechanisms of mechanical ripening include
endogenous prostaglandin production through induction of
a stretch force on myometrial cells and amnion that overlie
the internal cervical os. Common methods of mechanical
induction include use of a cervical Foley balloon catheter or
osmotic dilators.13
Both single and double Foley balloon catheters are available for use in the induction of labor process. Double-balloon
catheters incorporate a component that applies direct pressure
to the external os. In a systematic review, the more costly
Intrauterine fetal demise
Obstetric conditions
Preterm premature rupture of membranes
(PPROM)
Premature rupture of membranes (PROM)
340/7 – 366/7†
At diagnosis
Chorioamnionitis
At diagnosis
Suspected placental abruption
Individualized
Post-term pregnancy
At diagnosis
*Suggested timing for induction for each condition is listed. If the condition/
comorbidity is diagnosed after the gestational age listed, induction should be
considered at the time of diagnosis.
Table 3. Bishop Scoring System
†The decision to prolong pregnancy beyond 340/7 weeks of EGA with a diagnosis of PPROM requires shared decision-making with the patient and thorough
discussion and documentation of possible maternal and neonatal risks associated with prolonged expectant management.5
Score
Consistency Position Dilation, Effacement,
of Cervix
of Cervix
cm
%
Station
0
Firm
Posterior
0
0–30
1
Medium
Midposition
1–2
40–50
−2
Cervical Ripening
2
Soft
Anterior
3–4
60–70
−1, 0
If the cervical examination is deemed unfavorable, cervical ripening should be initiated. Cervical ripening is a
3
…
…
5–6
80
+1, +2
10
Adapted from Obstet Gynecol. 1964;24:266-268.
3
−3
Postgraduate Obstetrics & Gynecology
September 15, 2022
double-balloon catheters were reported to result in higher
pain scores, and did not demonstrate superior efficacy compared with single-balloon catheters.14 As such, use of singleballoon (Foley) catheters is recommended at this time.
Balloon catheters are placed transcervically followed by
inflation of the balloon tip with saline, generally between 30
and 60 mL, and traction is applied to the free end of the catheter.1,13 Data have demonstrated that balloon volumes greater
than 30 mL can reduce time from induction to delivery.15
When the cervix has reached 3 to 4 cm dilated, the balloon is
often expelled, typically achieving a favorable Bishop score.
Osmotic dilators, more commonly used for first and second-trimester pregnancy termination, achieve cervical dilation through the absorption of water and an associated
expansion in diameter.1,13 Osmotic dilators may be associated with an increased risk of peripartum infections felt to
be related to a longer duration of labor compared with
alternative methods.16 Use of a balloon catheter may be a
more optimal approach for induction of labor at later gestational ages if mechanical dilation is considered.
perceived risks of uterine hyperstimulation and limited data
regarding safety of administration without fetal surveillance.1,9 Cervical ripening with a Foley balloon, however,
has been documented to be safe for use in the outpatient
setting. A 2020 meta-analysis of available randomized controlled trials comparing inpatient versus outpatient Foley
catheter induction demonstrated outpatient insertion was
associated with a lower cesarean delivery rate and shorter
hospital stay.20 Initiation of the induction process with cervical Foley insertion in the outpatient setting is an acceptable approach for select patients.
Nipple Stimulation
Nipple stimulation is an inexpensive method for labor
induction, which offers women control during their induction course.1,21 This method has only been studied in lowrisk pregnancies, and protocols vary with use of breast
pumps for stimulation versus manual nipple stimulation.
The goal of any approach is to cause regular uterine contractions. A 2005 Cochrane review evaluated breast stimulation for induction compared with no intervention, and
noted an increased likelihood of entering labor in the stimulation group, which only reached statistical significance in
patients with a favorable cervix. There was notably a significant reduction in postpartum hemorrhage in the nipple
stimulation groups.21 Further study is needed to better
delineate protocols for nipple stimulation, and safety and
efficacy across patient populations.
Pharmacologic Cervical Ripening
Misoprostol is a prostaglandin-E1 analogue used commonly as a pharmacologic induction agent. When used for
induction of labor, misoprostol is most commonly administered orally or vaginally at doses of 25 to 50 µg initially,
followed by 25 µg every 3 to 6 hours as per provider preference.1,9,17 Contraindications to misoprostol include more
than 3 contractions in 10 minutes and previous uterine scar.1
Vaginal administration of misoprostol may result in a
shorter interval to vaginal delivery as compared with the
oral route.18 More recently, the Induction with MisoPRostol:
Oral mucosa versus Vaginal Epithelium (IMPROVE) study
compared the efficacy and safety of buccal versus vaginal
administration of misoprostol. In this triple-blinded, placebo-controlled study, vaginal administration of misoprostol resulted in shorter time to vaginal delivery and a lower
number of cesarean deliveries for nonreassuring fetal status
compared with the buccal administration group.19 Although
vaginal administration may have more favorable results, the
need for repetitive vaginal examinations for placement by
trained staff may limit its routine use.
An alternative cervical ripening agent is dinoprostone, an
analogue of prostaglandin-E2. Dinoprostone is available as
a vaginal gel or vaginal insert.1 In comparison with vaginal
misoprostol, vaginal dinoprostone is associated with lower
rates of uterine tachysystole, and the vaginal insert is readily
removed if needed for nonreassuring fetal status. However,
despite higher rates of uterine tachysystole with misoprostol, a parallel increase in adverse neonatal outcomes has not
been reported.17 Further, when compared with dinoprostone, vaginal misoprostol is significantly less expensive and
results in a shorter interval to vaginal delivery,17 and therefore may be a preferable agent for cervical ripening.
Amniotomy
Amniotomy, also known as artificial rupture of membranes, can be performed during the cervical examination,
typically after cervical ripening, to augment the induction
process.1,9,22 This procedure performed before the onset of
active labor is termed early amniotomy, whereas when performed during active labor is termed late amniotomy. A
2020 meta-analysis by De Vivo et al22 demonstrated that
early amniotomy after cervical ripening may shorten the
interval from induction start to delivery and was not associated with increased risk of cesarean delivery when compared with patients who underwent late amniotomy or
spontaneous rupture of membranes. Amniotomy is not
associated with increased pain, but may result in an
increased risk of infection, abnormal fetal heart rate tracing,
bleeding, and cord prolapse.23 As with all procedures,
patients should be informed on the potential risks and benefits of amniotomy after cervical ripening as a part of the
induction process.
Oxytocin
Oxytocin has been used since the early 1900s in the field
of obstetrics when it was first identified to aid in postpartum
hemorrhage and then used as a method to induce labor.24
Oxytocin is typically used either concurrently with mechanical ripening or after cervical ripening during induction.
Protocols for oxytocin are generally categorized into lowdose and high-dose regimens. Low-dose regimens start at a
dose of 0.5 to 2 mU/min and increase by 1 to 2 mU/min
Outpatient Cervical Ripening
Prostaglandin analogues are not widely used for cervical
ripening in the outpatient setting at this time due to
4
September 15, 2022
Topics in Obstetrics & Gynecology
for ripening, as available studies have not demonstrated an
increased risk of uterine rupture with Foley catheter induction.29 The use of oxytocin for induction and augmentation
of labor in patients with a prior uterine scar has been studied
with mixed results. When an increased risk of uterine rupture was documented, this risk remained small (~1.1%), and
as such use of oxytocin may be considered with close
monitoring in this patient population.28,29
every 15 to 40 minutes. High-dose protocols start at a dose
of 6 mU/min and increase by 3 to 6 mU/min every 15 to 40
minutes.1 High-dose regimens have been associated with an
increased risk of uterine tachysystole, but associated adverse
perinatal outcomes have not been demonstrated consistently across studies.25 Until further data are available on the
safety profile of high-dose regimens, low-dose regimens
should be considered. Hospital-specific protocols should be
used for provider guidance on oxytocin administration for
induction and augmentation of labor.
Induction in Second- or Third-Trimester Intrauterine
Fetal Demise
Combined Mechanical and Pharmacologic
Approaches
In the event of second- or third-trimester IUFD, options
for management may include dilation and evacuation
(depending on gestational age and provider experience),
hysterotomy, or induction of labor. Mode of delivery is a
shared decision between the patient and the provider, and
involves a thorough discussion of all potential risks and
benefits. If induction of labor is elected at less than 28
weeks of EGA, misoprostol in higher dosing regimens
(400–600 µg every 4–6 hours) is a recommended approach.
As an additional adjunct, mifepristone administered 24 to
48 hours in advance of misoprostol initiation has been
shown to reduce time to delivery when compared with misoprostol alone. In the event of a prior cesarean delivery
involving the lower uterine segment, misoprostol induction
may be considered in the second trimester. Optimal dosing
regimens for this population have yet to be determined, but
lower doses (200 µg) may be considered. For women with
or without a prior uterine scar, high-dose oxytocin regimens
are an appropriate alternative if prostaglandins are not available.30 Beyond 28 weeks of EGA, the regimens described
earlier for induction for a viable pregnancy are generally
used for induction for IUFD.1
Several studies have evaluated the efficacy and safety of
combining mechanical and pharmacologic approaches to
induction with results favoring a combined approach.
Levine et al26 randomized patients to induction of labor
initiated with vaginal misoprostol versus Foley catheter
alone versus cervical Foley with concurrent administration
of vaginal misoprostol versus cervical Foley with concurrent administration of oxytocin. Both combination methods
achieved a faster time to delivery, and when adjusted for
parity and censored for cesarean delivery, the cervical
Foley-misoprostol combination was superior to both singleagent methods studied.26 Gomez et al27 compared vaginal
and buccal administration of misoprostol combined with
cervical Foley catheter placement for induction. Vaginal
administration of misoprostol was notably superior to buccal administration in this study with a faster time to delivery
and greater percentage of vaginal delivery within 24 hours.
There were no significant differences in cesarean delivery
rates or maternal or neonatal outcomes studied.27 Based on
these reported outcomes, a combined mechanical and pharmacologic approach to induction should be considered
when clinically feasible.
Trauma-Informed Care in Induction of Labor
In the care of all patients, it is important to acknowledge
an individual’s lived experiences, and past or ongoing traumatic events that impact their life narrative. Trauma can
take many forms—intimate partner violence, sexual assault,
separation from family, and racism—and has also been
described related to prior difficult birth experiences. To
build trust and create a safe environment for patients, all
members of the care team should employ a traumainformed approach to care.31 When considering an approach
to induction of labor, a patient’s history and preferences
must be taken into account. Use of vaginally administered
medications or placement of a cervical Foley may result in
retraumatization for some patients, and can readily be
avoided by opting for alternative regimens such as oral misoprostol. Shared decision-making in the process of induction of labor, as with all components of the birth process, is
paramount to enabling a safe, secure experience for patients
and their providers.
Special Considerations
Patients With Prior Cesarean Delivery
Patients who have a history of 1 or 2 cesarean deliveries
remain candidates for induction of labor apart from those
with a history of classical cesarean delivery, or cesarean
delivery with extension into the active segment due to the
increased risk of uterine rupture.28 Multiple studies have
documented an increased risk of uterine rupture in patients
with prior cesarean undergoing induction of labor compared with spontaneous labor, with a less than 2% risk in
the former, and less than 1% risk in the latter. Despite the
slightly higher risk of uterine rupture, benefits of vaginal
delivery and avoidance of additional cesarean deliveries
may favor induction. Recommendations for methods of
induction in patients with a prior cesarean delivery are centered upon risks of uterine rupture. Prostaglandin analogues
for cervical ripening have consistently demonstrated the
highest risk of uterine rupture among available options,28,29
and are therefore not recommended in this patient population.1 The use of Foley catheters for induction in patients
with prior cesarean deliveries is considered a safe alternative
Failed Induction of Labor
The length of labor may be increased in patients undergoing induction of labor compared with those in spontaneous
5
Postgraduate Obstetrics & Gynecology
September 15, 2022
labor.9,32 Inductions declared as failed without adequate
attempt at achieving a vaginal birth can lead to an increased
incidence of primary cesarean deliveries. A failed induction
may be declared in the latent phase of labor (<6-cm dilation) if a patient has not reached the goal of regular contractions and cervical change either after rupture of membranes
and oxytocin administration for 12 to 18 hours, or with
intact membranes and oxytocin administration for at least
24 hours.32 Maternal and fetal status should be closely
monitored throughout with appropriate intervention to optimize perinatal outcomes as indicated.
in a longer interval to delivery compared with spontaneous
labor and allowing adequate time for progression through
the latent phase of labor with close maternal and fetal
monitoring will optimize chances for a successful vaginal
birth.
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13. Sciscione AC. Methods of cervical ripening and labor induction: mechanical. Clin Obstet Gynecol. 2014;57(2):369-376. doi:10.1097/GRF.0000000
000000023.
14. Yang F, Huang S, Long Y, et al. Double-balloon versus single-balloon catheter for cervical ripening and labor induction: a systematic review and metaanalysis. J Obstet Gynaecol Res. 2018;44(1):27-34. doi:10.1111/jog.13551.
15. Schoen CN, Saccone G, Backley S, et al. Increased single-balloon Foley
catheter volume for induction of labor and time to delivery: a systematic
review and meta-analysis. Acta Obstet Gynecol Scand. 2018;97(9):10511060. doi:10.1111/aogs.13353.
16. Krammer J, Williams MC, Sawai SK, et al. Pre-induction cervical ripening:
a randomized comparison of two methods. Obstet Gynecol. 1995;85(4):614618. doi:10.1016/0029-7844(95)00013-H.
17. Pierce S, Bakker R, Myers DA, et al. Clinical insights for cervical ripening
and labor induction using prostaglandins. AJP Rep. 2018;8(4):e307-e314.
doi:10.1055/s-0038-1675351.
18. Wing DA, Ham D, Paul RH. A comparison of orally administered misoprostol with vaginally administered misoprostol for cervical ripening and labor
induction. Am J Obstet Gynecol. 1999;180(5):1155-1160. doi:10.1016/
s0002-9378(99)70610-1.
19. Haas DM, Daggy J, Flannery KM, et al. A comparison of vaginal versus
buccal misoprostol for cervical ripening in women for labor induction at
term (the IMPROVE trial): a triple-masked randomized controlled trial. Am
J Obstet Gynecol. 2019;221(3):259.e1-259.e16. doi:10.1016/j.ajog.2019.
04.037.
20. Abdelhakim AM, Shareef MA, AlAmodi AA, et al. Outpatient versus inpatient balloon catheter insertion for labor induction: a systematic review and
meta-analysis of randomized controlled trials. J Gynecol Obstet Hum
Reprod. 2020;49(8):101823. doi:10.1016/j.jogoh.2020.101823.
Summary
Induction of labor is a safe and effective process to
achieve vaginal birth when the benefits of delivery outweigh the risks of remaining pregnant. The incidence of
induction of labor is steadily increasing with an anticipated
continued rise pending further studies reporting on the risks
and benefits of delivery after 39 weeks of EGA in broader
populations. Providers who offer induction of labor should
consider best practices for timing, methods for cervical
ripening, and optimal regimens to promote regular contractions and cervical change. Special considerations should be
recognized for patients with a prior uterine scar, and those
undergoing induction for IUFD. All parts of the induction
process should be followed with a trauma-informed lens,
and shared decision-making between the patient and the
provider. Understanding that inductions of labor may result
Practice Pearls
• Induction of labor is recommended when the benefits
of delivery outweigh the risks of remaining pregnant.
• Indications for inductions of labor include maternal,
fetal, or social/elective.
• Before proceeding with scheduling an induction of
labor, it is imperative to have an accurate estimated due
date.
• Methods to induce labor include cervical ripening with
mechanical methods or prostaglandins, membrane
sweeping, nipple stimulation, amniotomy, and oxytocin administration.
• The combination of mechanical cervical ripening with
Foley balloon and prostaglandin or oxytocin administration has been demonstrated to have shorter time to
delivery and a higher percentage of deliveries within
24 hours compared with single-method induction of
labor.
• Patients with less than 2 prior cesarean deliveries, apart
from those with a prior scar involving the active uterine
segment, are candidates for induction of labor; prostaglandin analogues should be avoided in these patients
due to increased risk of uterine rupture.
• A failed induction of labor should not be declared in
the latent phase of labor on oxytocin until at least 12 to
18 hours after rupture of membranes, or at least 24
hours with intact membranes.
6
September 15, 2022
Topics in Obstetrics & Gynecology
21. Kavanagh J, Kelly AJ, Thomas J. Breast stimulation for cervical ripening
and induction of labour. Cochrane Database Syst Rev. 2005;2005(3):
CD003392. doi:10.1002/14651858.CD003392.pub2.
22. De Vivo V, Carbone L, Saccone G, et al. Early amniotomy after cervical
ripening for induction of labor: a systematic review and meta-analysis of
randomized controlled trials. Am J Obstet Gynecol. 2020;222(4):320-329.
doi:10.1016/j.ajog.2019.07.049.
23. Smyth RM, Alldred SK, Markham C. Amniotomy for shortening spontaneous labour. Cochrane Database Syst Rev. 2013;(1):CD006167. doi:10.1002/
14651858.CD006167.pub3.
24. Theobald GW, Graham A, et al. The use of post-pituitary extract in physiological amounts in obstetrics: a preliminary report. Br Med J. 1948;2(4567):
123-127. doi:10.1136/bmj.2.4567.123.
25. Budden A, Chen LJ, Henry A. High-dose versus low-dose oxytocin infusion
regimens for induction of labour at term. Cochrane Database Syst Rev.
2014;2014(10):CD009701. doi:10.1002/14651858.CD009701.pub2.
26. Levine LD, Downes KL, Elovitz MA, et al. Mechanical and pharmacologic
methods of labor induction: a randomized controlled trial. Obstet Gynecol.
2016;128(6):1357-1364. doi:10.1097/AOG.0000000000001778.
27. Gomez HB, Hoffman MK, Caplan R, et al. Buccal vs vaginal misoprostol
combined with Foley catheter for cervical ripening at term (the BEGIN
28.
29.
30.
31.
32.
trial): a randomized controlled trial. Am J Obstet Gynecol. 2021;224(5):524.
e1-524.e8. doi:10.1016/j.ajog.2021.02.016.
ACOG Practice Bulletin No. 205: Vaginal Birth After Cesarean Delivery.
Obstet Gynecol. 2019;133(2):e110-e127. doi:10.1097/AOG.00000000
00003078.
Hoffman MK, Hunter Grant G. Induction of labor in women with a prior
cesarean delivery. Semin Perinatol. 2015;39(6):471-474. doi:10.1053/j.
semperi.2015.07.011.
Management of Stillbirth: Obstetric Care Consensus No, 10. Obstet
Gynecol. 2020;135(3):e110-e132. doi:10.1097/AOG.0000000000003719.
American College of Obstetricians and Gynecologists’ Committee on
Health Care for Underserved Women. Caring for Patients Who Have
Experienced Trauma: ACOG Committee Opinion, Number 825. Obstet
Gynecol. 2021;137(4):e94-e99. doi:10.1097/AOG.0000000000004326.
Spong CY, Berghella V, Wenstrom KD, et al. Preventing the first cesarean
delivery: summary of a joint Eunice Kennedy Shriver National Institute of
Child Health and Human Development, Society for Maternal-Fetal
Medicine, and American College of Obstetricians and Gynecologists
Workshop. Obstet Gynecol. 2012;120(5):1181-1193. doi:10.1097/
aog.0b013e3182704880.
Continuing Professional Development Quiz: Volume 42, Number 13
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7
Postgraduate Obstetrics & Gynecology
1.
A 35-year-old G2P1001 at 370/7 weeks of EGA presents for
induction of labor after diagnosis with gestational hypertension. She has a history of 1 low-segment transverse cesarean delivery. The best method for induction is
A. Foley balloon and misoprostol 50 µg administered
orally.
B. Foley balloon and dinoprostone vaginal insert.
C. Foley balloon and oxytocin.
D. none of the above; the patient is not a candidate for
induction of labor.
2.
A 29-year-old G1P0 at 253/7 weeks of EGA presents for
routine prenatal care. She recently learned about induction
of labor from a friend. During the visit, she asks you about
potential indications for induction of labor. All of the following are indications for induction of labor, except
A. placenta previa.
B. chronic hypertension.
C. gestational diabetes.
D. premature rupture of membranes.
3.
4.
September 15, 2022
A 34-year-old G1 at 374/7 weeks of EGA with an uncomplicated prenatal course presents to discuss elective induction at 39 weeks. Which one of the following statements
regarding the ARRIVE trial is true?
A. The ARRIVE trial included only multiparous patients.
B. Patients who underwent induction of labor had a lower
rate of cesarean deliveries compared with patients
who were expectantly managed.
C. The ARRIVE trial included patients with high-risk pregnancies.
D. Patients who underwent induction of labor had a
higher frequency of adverse perinatal outcomes compared with patients who were expectantly managed.
Which one of the following mechanical cervical ripening
devices is best suited to optimize induction of labor in the
third trimester of pregnancy?
A. osmotic dilators
B. Foley balloon catheter filled with 30 mL of saline
C. Foley balloon catheter filled with 60 mL of saline
D. Double-balloon catheter
5.
A 25-year-old G1P0 at 34 weeks has a pregnancy complicated by gestational diabetes, which is managed with longacting insulin. Her blood sugar levels are well controlled.
Induction of labor should be recommended at
A. 360/7 to 386/7 weeks.
B. 390/7 to 396/7 weeks.
C. 400/7 to 416/7 weeks.
D. 340/7 to 346/7 weeks.
6.
A 33-year-old G3P1011 at 246/7 weeks of EGA is diagnosed with IUFD. She would like to proceed with induction.
Which of the following regimens should be recommended
to reduce time to delivery?
A. Foley balloon and low-dose oxytocin
B. misoprostol alone
C. osmotic dilators and low-dose oxytocin
D. mifepristone followed by misoprostol
7.
A 42-year-old G1 is undergoing induction of labor for gestational hypertension at 386/7 weeks of EGA. To address
her concerns that induction may fail, you counsel her that
patients undergoing induction are diagnosed with failed
induction in the latent phase (<6-cm dilation) if they fail to
achieve regular contractions and cervical change with
A. ruptured membranes and on oxytocin for 12 to
18 hours.
B. ruptured membranes and on oxytocin for 6 hours.
C. intact membranes and on oxytocin for 12 to 18 hours.
D. intact membranes and on oxytocin for 6 hours.
8.
A patient is admitted at 370/7 weeks of EGA for induction,
after a new diagnosis of fetal growth restriction, with estimated fetal weight in the second percentile. The patient
asks you about the role of amniotomy in induction. Which
one of the following statements comprises appropriate
counseling?
A. Early amniotomy is associated with an increased risk
of cesarean delivery.
B. Amniotomy is a painful procedure.
C. Early amniotomy after cervical ripening can shorten
the time from the start of induction to delivery.
D. Amniotomy is not associated with an increased risk of
infection.
9.
A 29-year-old G3P2002 is scheduled to undergo induction
of labor at 340/7 weeks for preeclampsia with severe features. Her cervical examination Bishop score is 3. She has
a reactive nonstress test and no other significant medical,
surgical, or social history. Which one of the following is the
best method to start induction in this patient?
A. Foley balloon catheter with vaginal misoprostol
B. Foley balloon catheter with buccal misoprostol
C. oxytocin alone
D. misoprostol alone
10. A 15-year-old G1 adolescent girl is scheduled to undergo
induction of labor for worsening intrahepatic cholestasis of
pregnancy at 372/7 weeks of EGA. She has a history of
sexual assault and difficulty tolerating vaginal examinations. At her more recent examination her cervix was
closed and long. With a goal of minimizing retraumatization, which one of the following is the best approach to
begin her induction?
A. oxytocin
B. oral misoprostol
C. vaginal misoprostol
D. dinoprostone
8