Cervical Ripening and Induction of Labor

Vernon Wheeler; Ariel Hoffman; Michael Bybel

VERNON WHEELER, MD, ARIEL HOFFMAN, MD, AND MICHAEL BYBEL, DO

This is a corrected version of the article that appeared in print.

Am Fam Physician. 2022;105(2):177-186

This clinical content conforms to AAFP criteria for CME.

Author disclosure: No relevant financial relationships.

Induction of labor is a common obstetric procedure, and approximately one-fourth of pregnant patients undergo the procedure. Although exercise and nipple stimulation can increase the likelihood of spontaneous labor, sexual intercourse may not be effective. Acupuncture has been used for labor induction; however, it has not been shown to increase vaginal delivery rates. There is strong evidence that membrane sweeping can increase the likelihood of spontaneous labor within 48 hours. Cervical preparation or ripening is often needed before induction. Some evidence shows that the use of nonpharmacologic approaches such as osmotic dilators and cervical ripening balloons reduce time to delivery. The effect of amniotomy on labor is uncertain. Pharmacologic intervention with oxytocin or prostaglandins is effective for cervical ripening and induction of labor. Combining a balloon catheter with misoprostol is a common practice and has been shown to decrease time to delivery in a small study.

Induction of labor is one of the most common obstetric procedures and is performed for approximately one-fourth of pregnancies.^1–3 Induction involves establishing cervical favorability, also called cervical ripening, and stimulating contractions to induce active labor.

Clinical recommendation	Evidence rating	Comments
Avoid induction of labor before 39 weeks' gestation if there is no medical indication.^5,6	B	Consistent evidence of improved patient outcomes in a large cohort study; practice guideline
Avoid prostaglandins in patients with prior cesarean delivery or major uterine surgery because of the increased risk of uterine rupture.^1,17,18	C	Practice guideline; prospective and retrospective cohort studies
Regular, moderate exercise and breast massage both increase the likelihood of spontaneous labor.^27,28	B	Small randomized controlled trials
Membrane sweeping in the outpatient setting can increase the likelihood of spontaneous labor within 48 hours.³²	B	Cochrane review of lower-quality studies
Consider outpatient placement of a Foley catheter for cervical ripening in nulliparous patients with an unfavorable cervix (full Bishop score of less than 6).^45,46	B	Lower-quality or inconsistent evidence, with no benefit in one trial of parous women but shorter time to delivery in another trial of only nulliparous women
Consider using vaginal misoprostol (Cytotec) for cervical ripening to increase the likelihood of vaginal delivery within 24 hours.^38–41	B	Randomized controlled trials and systematic review
Consider combining a balloon catheter and misoprostol for cervical ripening to shorten time to delivery.³⁴	B	Randomized controlled trial

Recommendation	Sponsoring organization
Do not schedule non–medically indicated (elective) inductions of labor or cesarean deliveries before 39 weeks 0 days gestational age.	American Academy of Family Physicians American College of Obstetricians and Gynecologists

Indications for Induction

Induction of labor is indicated when the risks of continuing the pregnancy outweigh the risks of induction, with the goal of delivery while minimizing risks to the mother and newborn. Maternal, fetal, and placental conditions can increase the risk of continuing a pregnancy. Common medical indications for induction of labor and recommended timing are covered in Table 1.⁴ [corrected]

Indication	Suggested timing (weeks' gestation)

	Earliest	Before
Maternal
Chronic hypertension
No medications	38	40
Well controlled	37	40
Poorly controlled or proteinuria	36	38
Gestational hypertension	37	At diagnosis if later than 37
Preeclampsia
No severe features	37	At diagnosis if later than 37
Severe features (immediate if unstable)	34	At diagnosis if later than 34
Prepregnancy diabetes mellitus
Well controlled	39	40
Well controlled but vascular disease	36	39
Poorly controlled	36	39
Gestational diabetes
Well controlled with diet (A1)	39	41
Well controlled with medication (A2)	39	40
Poorly controlled	Individualized
Cholestasis of pregnancy	36	39
HIV infection (if viral load ≤ 1,000 copies per mL)	39	—
Fetal
Fetal growth restriction
Single gestation, no issues	38	39
Single gestation, other conditions	34	38
Twin gestation, no issues	36	38
Twin gestation, monochorionic or other condition	32	35
Oligohydramnios	36	38
Polyhydramnios	39	41
Alloimmunization	37	39
Multiple gestation
Dichorionic diamniotic	38	39
Monochorionic diamniotic	34	38
Monochorionic monoamniotic	32	34
Obstetric
History of stillbirth	Individualized
Late term	41	42
Note: The placental disorders placenta previa, vasa previa, and invasive placental disorders were removed from this table because all typically require cesarean delivery.

Induction of labor before 39 weeks' gestation increases neonatal morbidity and mortality and is not recommended without a medical indication.^5,6 Several studies demonstrate that induction of labor at 41 weeks leads to similar outcomes as induction at 42 weeks. Pregnancies that exceed 42 weeks' gestation have increased neonatal morbidity, including convulsions, meconium aspiration, and need for intensive care.⁷

TIMING OF ELECTIVE INDUCTION

Until recently, elective inductions before 41 weeks' gestation have been controversial because of a lack of evidence. A large randomized trial showed that elective inductions at 39 weeks' gestation or later are associated with improved outcomes in first pregnancies.⁸ In this trial of low-risk nulliparous women, elective induction at 39 weeks to 39 weeks 4 days had similar neonatal mortality and morbidity as delivery at 40 weeks 5 days or later. Infants from the elective induction group had less need for respiratory support, with a number needed to treat (NNT) of 83 to prevent respiratory support in the first 72 hours of life.

There were also several other improved outcomes with elective induction. Elective induction reduced cesarean delivery (NNT = 28 to prevent one cesarean delivery) and reduced hypertensive pregnancy disorders (NNT = 17).⁸ The Society for Maternal-Fetal Medicine and the American College of Obstetricians and Gynecologists endorse offering elective induction of labor at 39 weeks' gestation to low-risk nulliparous pregnant individuals under circumstances that are consistent with this trial's study protocol.^9,10

INDUCTION OF LABOR AFTER PRIOR CESAREAN DELIVERY

There are several reasons for choosing a trial of labor after a cesarean delivery (TOLAC) instead of a repeat cesarean delivery, including shorter hospital stay, shorter recovery time, and reduced pain after delivery. Careful counseling is required before TOLAC because of risks, including uterine rupture.^11,12 A validated calculator is available to assist when deciding on TOLAC vs. a repeat cesarean delivery (https://mfmunetwork.bsc.gwu.edu/web/mfmunetwork/vaginal-birth-after-cesarean-calculator). This calculator was updated to remove the race and ethnicity component, which does not affect the validity.¹³

For individuals who have had one prior cesarean delivery, TOLAC may reduce rates of cesarean delivery.^14–16 In 2019, the American Academy of Family Physicians reaffirmed clinical practice guidelines for management of TOLAC (https://www.aafp.org/family-physician/patient-care/clinical-recommendations/all-clinical-recommendations/vaginal-birth-after-cesarean.html). Cervical ripening balloons and oxytocin (Pitocin) are appropriate agents for TOLAC, but prostaglandin use increases the risk of uterine rupture and should be avoided.^1,17,18

ACOG practice bulletin no. 107: induction of labor. Obstet Gynecol. 2009;114(2 pt 1):386-397.

Martin JA, Hamilton BE, Osterman MJK, et al.; Births: final data for 2015. Natl Vital Stat Rep. 2017;66(1):1.

Osterman MJK, Martin JA. Recent declines in induction of labor by gestational age. NCHS Data Brief. 2014;(155):1-8.

ACOG Committee on Obstetric Practice, Society for Maternal-Fetal Medicine; Medically indicated late-preterm and early-term deliveries: ACOG committee opinion, number 831. Obstet Gynecol. 2021;138(1):e35-e39.

Tita ATN, Landon MB, Spong CY, et al; Eunice Kennedy Shriver NICHD Maternal-Fetal Medicine Units Network; Timing of elective repeat cesarean delivery at term and neonatal outcomes. N Engl J Med. 2009;360(2):111-120.

ACOG committee opinion no. 765: avoidance of nonmedically indicated early-term deliveries and associated neonatal morbidities. Obstet Gynecol. 2019;133(2):e156-e163.

ACOG practice bulletin no. 146: management of late-term and post-term pregnancies. Obstet Gynecol. 2014;124(2 pt 1):390-396.

Grobman WA, Rice MM, Reddy UM, et al; Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal–Fetal Medicine Units Network; Labor induction versus expectant management in low-risk nulliparous women. N Engl J Med. 2018;379(6):513-523.

Society of Maternal-Fetal (SMFM) Publications Committee; SMFM statement on elective induction of labor in low-risk nulliparous women at term: the ARRIVE trial. Am J Obstet Gynecol. 2019;221(1):B2-B4.

ACOG Committee on Obstetric Practice. Clinical guidance for integration of the findings of the ARRIVE trial: labor induction versus expectant management in low-risk nulliparous women. August 2018. Accessed September 16, 2021. https://www.acog.org/clinical/clinical-guidance/practice-advisory/articles/2018/08/clinical-guidance-for-integration-of-the-findings-of-the-arrive-trial

Al-Shaikh G, Al-Mandeel H. The outcomes of trial of labour after cesarean section following induction of labour compared to spontaneous labour. Arch Gynecol Obstet. 2013;287(6):1099-1103.

Bernstein SN, Matalon-Grazi S, Rosenn BM. Trial of labor versus repeat cesarean: are patients making an informed decision?. Am J Obstet Gynecol. 2012;207(3):204.e1-204.e6.

Grobman WA, Sandoval G, Rice MM, et al.; Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Prediction of vaginal birth after cesarean delivery in term gestations: a calculator without race and ethnicity [published online May 24, 2021]. Am J Obstet Gynecol. Accessed August 24, 2021. https://www.ajog.org/article/S0002-9378(21)00587-1/fulltext

Landon MB, Leindecker S, Spong CY, et al; National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network; The MFMU cesarean registry: factors affecting the success of trial of labor after previous cesarean delivery. Am J Obstet Gynecol. 2005;193(3 pt 2):1016-1023.

Palatnik A, Grobman WA. Induction of labor versus expectant management for women with a prior cesarean delivery. Am J Obstet Gynecol. 2015;212(3):358.e1-358.e6.

Metz TD, Stoddard GJ, Henry E, et al.; How do good candidates for trial of labor after cesarean (TOLAC) who undergo elective repeat cesarean differ from those who choose TOLAC?. Am J Obstet Gynecol. 2013;208(6):458.e1-458.e6.

West HM, Jozwiak M, Dodd JM. Methods of term labour induction for women with a previous caesarean section. Cochrane Database Syst Rev. 2017;(6):CD009792.

ACOG practice bulletin no. 205: vaginal birth after cesarean delivery. Obstet Gynecol. 2019;133(2):e110-e127.

Bishop EH. Pelvic scoring for elective induction. Obstet Gynecol. 1964;24:266-268.

Ezebialu IU, Eke AC, Eleje GU, et al.; Methods for assessing pre-induction cervical ripening. Cochrane Database Syst Rev. 2015;(6):CD010762.

Laughon SK, Zhang J, Troendle J, et al.; Using a simplified Bishop score to predict vaginal delivery. Obstet Gynecol. 2011;117(4):805-811.

Baacke KA, Edwards RK. Preinduction cervical assessment. Clin Obstet Gynecol. 2006;49(3):564-572.

Raghuraman N, Stout MJ, Young OM, et al.; Utility of the simplified Bishop score in spontaneous labor. Am J Perinatol. 2016;33(12):1176-1181.

Park KH, Kim SN, Lee SY, et al.; Comparison between sonographic cervical length and Bishop score in preinduction cervical assessment: a randomized trial. Ultrasound Obstet Gynecol. 2011;38(2):198-204.

Bartha JL, Romero-Carmona R, Martínez-Del-Fresno P, et al.; Bishop score and transvaginal ultrasound for preinduction cervical assessment: a randomized clinical trial. Ultrasound Obstet Gynecol. 2005;25(2):155-159.

Boozarjomehri F, Timor-Tritsch I, Chao CR, et al.; Transvaginal ultrasonographic evaluation of the cervix before labor: presence of cervical wedging is associated with shorter duration of induced labor. Am J Obstet Gynecol. 1994;171(4):1081-1087.

Pereira IB, Silva R, Ayres-de-Campos D, et al. Physical exercise at term for enhancing the spontaneous onset of labor: a randomized clinical trial. J Matern Fetal Neonatal Med. 2020;:1-5.

Singh N, Tripathi R, Mala YM, et al.; Breast stimulation in low-risk primigravidas at term: does it aid in spontaneous onset of labour and vaginal delivery? A pilot study. Biomed Res Int. 2014;2014:695037.

Carbone L, De Vivo V, Saccone G, et al.; Sexual intercourse for induction of spontaneous onset of labor: a systematic review and meta-analysis of randomized controlled trials. J Sex Med. 2019;16(11):1787-1795.

Smith CA, Armour M, Dahlen HG. Acupuncture or acupressure for induction of labour. Cochrane Database Syst Rev. 2017;(10):CD002962.

Kelly AJ, Kavanagh J, Thomas J. Castor oil, bath and/or enema for cervical priming and induction of labour. Cochrane Database Syst Rev. 2013(7):CD003099.

Finucane EM, Murphy DJ, Biesty LM, et al.; Membrane sweeping for induction of labour. Cochrane Database Syst Rev. 2020;(2):CD000451.

Kabiri D, Hants Y, Yarkoni TR, et al.; Antepartum membrane stripping in GBS carriers, is it safe? (The STRIP-G study). PLoS One. 2015;10(12):e0145905.

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.

de Vaan MD, Ten Eikelder ML, Jozwiak M, et al.; Mechanical methods for induction of labour. Cochrane Database Syst Rev. 2019;(10):CD001233.

Saad AF, Villarreal J, Eid J, et al.; A randomized controlled trial of Dilapan-S vs Foley balloon for preinduction cervical ripening (DILAFOL trial). Am J Obstet Gynecol. 2019;220(3):275.e1-275.e9.

Triglia MT, Palamara F, Lojacono A, et al.; A randomized controlled trial of 24-hour vaginal dinoprostone pessary compared to gel for induction of labor in term pregnancies with a Bishop score < or = 4. Acta Obstet Gynecol Scand. 2010;89(5):651-657.

Young DC, Delaney T, Armson BA, et al.; Oral misoprostol, low dose vaginal misoprostol, and vaginal dinoprostone for labor induction: randomized controlled trial. PLoS One. 2020;15(1):e0227245.

McMaster K, Sanchez-Ramos L, Kaunitz AM. Balancing the efficacy and safety of misoprostol: a meta-analysis comparing 25 versus 50 micrograms of intravaginal misoprostol for the induction of labour. BJOG. 2015;122(4):468-476.

Souza ASR, Amorim MMR, Feitosa FEL. Comparison of sublingual versus vaginal misoprostol for the induction of labour: a systematic review. BJOG. 2008;115(11):1340-1349.

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.

Prichard N, Lindquist A, Hiscock R, et al.; High-dose compared with low-dose oxytocin for induction of labour of nulliparous women at term. J Matern Fetal Neonatal Med. 2019;32(3):362-368.

Budden A, Chen LJY, Henry A. High-dose versus low-dose oxytocin infusion regimens for induction of labour at term. Cochrane Database Syst Rev. 2014;(10):CD009701.

Cook cervical ripening balloon with stylet (instructions for use). Cook Medical Europe Ltd; 2021. Accessed August 24, 2021. https://www.cookmedical.com/data/IFU_PDF/T_J-CCRBS_REV3.PDF

Kuper SG, Jauk VC, George DM, et al.; Outpatient Foley catheter for induction of labor in parous women: a randomized controlled trial. Obstet Gynecol. 2018;132(1):94-101.

Ausbeck EB, Jauk VC, Xue Y, et al.; Outpatient Foley catheter for induction of labor in nulliparous women: a randomized controlled trial. Obstet Gynecol. 2020;136(3):597-606.

Levine LD, Sciscione AC. Foley catheter for outpatient cervical ripening: review of the evidence and a proposed model of care. Am J Perinatol. 2019;36(14):1528-1532.

Dilapan-S (hygroscopic cervical dilator). Medicem Inc; 2021. Accessed August 24, 2021. https://www.dilapans.com/pdf/Dilapan-S%20IFU.pdf

Smyth RMD, Markham C, Dowswell T. Amniotomy for shortening spontaneous labour. Cochrane Database Syst Rev. 2013;(6):CD006167.

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.

Arias F. Pharmacology of oxytocin and prostaglandins. Clin Obstet Gynecol. 2000;43(3):455-468.

ACOG committee opinion no. 766: approaches to limit intervention during labor and birth. Obstet Gynecol. 2019;133(2):e164-e173.

Alfirevic Z, Kelly AJ, Dowswell T. Intravenous oxytocin alone for cervical ripening and induction of labour. Cochrane Database Syst Rev. 2009;(4):CD003246.

Tenore JL. Methods for cervical ripening and induction of labor. Am Fam Physician. 2003;67(10):2123-2128. Accessed August 24, 2021. https://www.aafp.org/afp/2003/0515/p2123.html

Harman JH, Kim A. HarmanJHJrKimACurrent trends in cervical ripening and labor induction. [published correction appears in Am Fam Physician. 1999;60(8):2238]Am Fam Physician1999;60(2):477–84. Accessed August 24, 2021. https://www.aafp.org/afp/1999/0801/p477.html

Indications for Induction

TIMING OF ELECTIVE INDUCTION

INDUCTION OF LABOR AFTER PRIOR CESAREAN DELIVERY

Continue Reading

More in AFP

More in Pubmed

Indications for Induction

TIMING OF ELECTIVE INDUCTION

INDUCTION OF LABOR AFTER PRIOR CESAREAN DELIVERY

Subscribe

Issue Access

Article Only

Continue Reading

More in AFP

More in Pubmed