Induction of Labor Controversies, Criteria, and Consequences Jamie Otremba, CNM, APRN, MSN

Definition of Induction of Labor: Stimulation of uterine contractions prior to the onset of spontaneous labor to accomplish delivery.

Incidence of Induction 1990- 10% 2010-40% 2010-2017- trending down, slowly. (30%) 40-75% elective No improved outcomes with increased rate of induction 20% of pregnancies require induction

WHY? Patient desire/convenience Provider lifestyle/balance Economic reasons for providers Concern over increased incidence of complication over 39 wks

Induction of labor should be undertaken when the benefits to either the mother or fetus outweigh the risks of continuing the pregnancy. -ACOG

Medical Indications: ACOG Committee Opinion 560: Medically-Indicated Late-Preterm and Early-Term Deliveries Placental/uterine issues Previa, myomectomy Fetal issues IUGR, multiples, oligo Maternal issues Chronic HTN, diabetes Obstetric issues PROM 2/3 are for nonmedical reasons

Suspected fetal macrosomia is not an indication for labor induction: it does not improve outcomes. -ACOG

Elective induction of labor The major risks: iatrogenic prematurity increased rates of cesarean delivery (67% incr risk) increased cost

Requirements for Induction Confirmation of term gestation >39 wks if elective Favorable cervix per Bishop Score ≥ 8 for multip, ≥ 10 for a prime No ripening for electives Informed consent Indications/alternatives Techniques Possibility of cesarean delivery, failed induction Increased risk of more intervention Possibility of cancelation

Induction Checklists ACOG Intermountain Healthcare Include Indication: elective vs. medical (document) Gestation and how it was established Bishop score EFW Consent obtained Pertinent lab work Hard stop

Most important factor in predicting success: Favorable cervix

Predicting Success Bishop score CERVIX 1 2 3 Position Posterior Mid Bishop EH. Pelvic scoring for elective induction. Obstet Gynecol 1964;24:266-8. CERVIX 1 2 3 Position Posterior Mid Anterior -- Consistency Firm Medium Soft Effacement 0-30% 40-50% 60-70% >80% Dilation Closed 1-2cm 3-4cm ≥5 Station -3 -2 -1, 0 +1,+2,+3 low Bishop score is particularly predictive of failure in nulliparous women who undergo elective induction of labor at term, although Bishop scoring was originally described in multiparous women The role of fFN as a tool for selecting women likely to have a successful induction remains uncertain. More data, including cost-benefit analysis, is needed before this test can be recommended in choosing candidates for semi-elective induction. More data, including cost-benefit analysis, is needed before this test can be recommended in choosing candidates for semi-elective induction

% C-Section by Bishop Score Primiparous Women

Hours of Labor by Bishop Score Primiparous Women

Cervical Ripening for Medical Induction of Labor Complex process that results in physical softening and distensibility of the cervix Enzymatic dissolution of collagen fibrils Increase in water content of the cervix Chemical changes contribute to effacement and early dilatation

Cervical Ripening Mechanical methods Chemical methods Time Effectiveness impacts induction success rate

Weekly membrane stripping No improvement in outcomes May cause concerns and result in hospital evaluation: $$ Form of induction: not before 39 wks Most benefit with multips May increase labor in next 24-48 hrs, and more likely to go into labor in the next 7 days Lowers risk of post-term pregnancy Spontaneous delivery is more likely Caution if GBS pos

Amniotomy Partially dilated and effaced cervix Shortens delivery timing by 2 hrs with oxytocin Not effective alone as induction agent Risks Infection barrier is removed Cord prolapse Commits you to delivery Most commonly performed obstetrical procedure

Balloon Catheters Foley catheter 30-60 cc No increased risk of infections No ‘traction’: may cause trauma, no benefit Outpatient? ACOG: reasonable, effective option Double balloon catheters More expensive No more effective per studies

Nipple Stimulation More women in labor within 72 hours Varying protocols Limited data Risks Hyperstimulation Increase in meconium stained fluid

Prostaglandin E2 (FDA approved) Prepidil 0.5 mg of dinoprostone in 2.5 mL of gel for intracervical administration Can be repeated in 6 to 12 hours Maximum cumulative dose of dinoprostone not exceed 1.5 mg (ie, three doses) within a 24 hour period 6 to 12 hours between the final dose and initiation of oxytocin $75/dose Cervidil 10 mg of dinoprostone Timed-release formulation Administers medication at 0.3 mg/h and should be left in place for 12 hours Oxytocin may be initiated 30 to 60 minutes after removal of the insert $150 Can be removed if tachysystole because of the potential for uterine hyperstimulation with concurrent oxytocin and prostaglandin administration

Prostaglandin E1: Misoprostol Off label use, not FDA approved for OB Gastric ulcer treatment 100mcg and 200mcg tabs, unscored Oral vs. vaginal vs. buccal vs. sublingual routes Oral and vaginal most data Oral safer Vaginal slightly faster Buccal and Sublingual: Limited studies avoid first pass higher total bioavailabilty possibly more tachysystole

Misoprostol-Safety Not for VBACS/prior uterine surgery ^ risk of meconium/uterine hyper-stimulation Safest doses: 25mcg q 3-6 hrs WHO recommended dose May reeval and consider increase to 50mcg if ineffective Monitoring Outpatient not currently recommended Indicated for 0.5 to 2 hours ACOG practice Bulletin No.107 Misoprostol vaginal insert available in Europe monitoring should be continuous while in hospital setting until further studies

Misoprostol-Efficacy Cochrane Database: More effective than other prostaglandins for: Labor induction Increased cervical ripening Achieving vaginal delivery in 24 hours Reduced use of oxytocin augmentation More effective than oxytocin for labor induction

Misoprostol-Dosing Oral administration Intra-vaginally Peaks sooner and declines more rapidly 25-50mcg q 3-6 hrs WHO 25mcg q 2 hrs Less tachysystole Less effect on FHTs More comfortable for patient Intra-vaginally 25-50 mcg every 3-6 hrs More uterine hyperstimulation Oxytocin: Minimum 4 hours after last misoprostol dose

Qualitative Comparisons of Various Routes of Administration of Misoprostol Pharmaco-kinetics Oral Vaginal Rectal Sublingual Onset Rapid Slower Peak High Lower Highest Duration Short Long Total Bioavailabilty Low 2-3X oral 1.5X oral

“The safest method for ripening the cervix and inducing labor appears to be administration of misoprostol orally (25 mcg every 4 hours).” Hofmeyr GJ, Cochrane Database of Systematic Reviews 2017

IV Oxytocin Low-dose vs high-dose protocols 40 min to steady state, 5 minute half-life D5 IV fluids may shorten labor (76 min)? Optimal 1-2mu/min increased every 30 min Less tachysystole Duration of labor equivalent to high or pulsatile dosing Increased to ‘labor’ normal progression strong contractions q 2-3 minutes 150 to 350 Montevideo units (200-250 median)

Oxytocin per ACOG Continuous monitoring required Provider within 10 minutes Order for exceeding 20mu/min needed

Elective Inductions: Trends Not for primes No electives advised by AWHONN

Other labor stimulators/ “partus preparers” Castor oil Intercourse Red raspberry leaf tea Homeopathy Acupuncture/acupressure Evening primrose oil Mother’s Cordial Ambulation Spicy food Dates

Thank you