1. Getting Things Started… Cervical Ripening and Labor Induction
Jennifer Frank MD
Fox Valley FMR Program

2. The best teachers… Are our patients.
Case 1: 36 yo G2P1 at 39 weeks for social induction.
VBAC
Cytotec for cervical ripening
Case 2: 29 yo G1 at weeks for social induction

3. Take home points (or learning objectives)
Cervical ripening, labor induction, and labor augmentation carry risks that are potentially serious to mom and baby and must be weighed by the potential benefit.
There is good evidence to direct the safe use of cervical ripening agents and agents used for labor induction and labor augmentation.
There are clinical indications when labor induction (+/- cervical ripening) is appropriate.

4. Indications for Labor Induction
Maternal and fetal indications
Placental abruption
Chorioamnionitis
Fetal demise
Gestational hypertension, preeclampsia, eclampsia
Premature ROM
Postterm pregnancy
Maternal medical indications
Fetal compromise (e.g. IUGR)

5. Indications for Induction
Other types of indications
Risk of rapid labor
Distance from hospital
Psychosocial indications
ACOG Practice Guideline No Induction of labor.

6. Contraindications to Labor Induction
Vasa previa
Complete placenta previa
Transverse fetal lie
Umbilical cord prolapse
Previous transfundal uterine surgery
ACOG Practice Guideline No Induction of labor.

7. Additional Contraindications
Absolute
Pelvic structural abnormality
Active genital herpes infection
Invasive cervical cancer
Relative
Abnormal FHT
Breech presentation
Maternal heart disease
Multifetal pregnancy
Polyhydramnios
Presenting part above pelvic inlet
Severe maternal hypertension
Harman JH, Kim A. Current trends in cervical ripening and labor induction. AFP 1999;60:

8. Successful Labor Induction
Different definitions of success
Achieve vaginal delivery in specified time (12-24 hours)
Achieve active labor within a specified time
Achieve active labor

9. Factors Predicting Success
Cervical status
Traditional Bishop score > 9
Favorable score varies from > 5 to > 8
Inverse relationship b/w cervical score and length of latent phase of labor
Increased risk of cesarean delivery with “unfavorable” cervix (generally < 5)
Crane JM. Factors predicting labor induction success: A critical analysis 2006;
Clin Obstet Gynecol 49;

10. Maternal Factors Maternal characteristics Parity Height Weight Age
Variable evidence for the weight this has on predicting delivery within 24 hours
Height
Association between taller women and increased chance of vaginal delivery within hours of starting labor induction
Weight
Lower weight – more likely to be successful
Age
Younger women are more likely to be successful

11. Fetal Factors
Higher birth weights (>3.5 kg) associated with increased risk for failed induction (lower rate of vaginal delivery within 24 hours)
Increasing gestational age associate with increased likelihood of labor induction success

12. Fetal maturity Criteria for establishing fetal maturity
 Fetal heart tones documented for at least 20 weeks by nonelectronic fetoscope or for 30 weeks by Doppler
At least 36 weeks since a positive HCG (serum or urine)
At least 39 weeks' gestation based on crown-rump length performed at 6–11 weeks' gestation
At least 39 weeks' gestation based on ultrasound measurement at 12–20 weeks' gestation
Sanchez-Ramos L. Induction of labor. Obstet Gynecol Clin North Am - 01-JUN-2005; 32(2): , viii

13. Cervical Ripening
Softening, effacement, dilation preceding active labor
Prostaglandins play an unknown role in mediating cervical ripening
When is it needed?
“Unripe cervix” based on cervical score (usually < 6 on Bishop score)

14. Bishop score Factor 1 2 3 Dilation 1-2 3-4 5-6 Effacement (%) 0-301 2 3
Dilation
1-2
3-4
5-6
Effacement (%)
0-30
40-50
60-70 80
Station -3 -2
-1 or 0
+1 to +2
Consistency
Firm
Med
Soft
___
Position
Post
Mid
Anter

15. Assessing Cervix TVUS Fetal fibronectin
More objective
Not superior to Bishop score in meta-analysis
Fetal fibronectin
May bind placenta and membranes to decidua
Presence associated with preterm birth
Not superior to Bishop score
Insulin-like growth factor binding protein-1
Synthesized by maternal decidua, may be released with cervical ripening and fetal membrane separating from decidua
May indicate cervical “ripeness”

16. Methods of cervical ripening
Low dose oxytocin
< 4 mU/minute
Dinoprostone (PGE2)
Intravaginal or intracervical
FDA approved for cervical ripening
Pt needs to be recumbent for 30 minutes and should be monitored for 1-4 hours
Onset of contractions usu. within 1st hour, peak at 4 hours

17. Methods of cervical ripening continued
Misoprostol: PGE1
Not FDA approved for this indication
Oral or vaginal administration*
3x systemic bioavailability of vaginal vs. oral
As or more effective than other methods
Increased risk of tachysystole
Has not equated with worse overall outcomes
Hyperstimulation occurs in 1-10% of patients
Cheaper and more convenient
Recommend informed consent

18. Nonpharmacologic methods for cervical ripening
Stripping or sweeping the membranes
Causes an increase in prostaglandins
Insert finger through internal cervical os and move in a circular direction to detach the inferior part of the membranes from the lower uterine segment
Risks: infection, bleeding, accidental amniotomy, discomfort
Alone is not effective but may reduce dose of oxytocin needed
Important note: Strippingmembranes.com is for sale

19. Nonpharmacologic methods for cervical ripening continued
Mechanical dilators – local pressure stimulating release of prostaglandins and dilating cervix
Hygroscopic (osmotic) dilators
Balloon devices (Foley bulb)
Method & materials
Effective for cervical ripening (compared to misoprostol, PGE2)
Amniotomy
Increases production/release of prostaglandins
Evidence does not support use for labor induction

20. Alternative methods for cervical ripening
Evening primrose oil, Black Haw, Black and blue cohosh, red raspberry leaves
All have uncertain role
Castor oil, hot baths, enemas
No evidence to support use
Sexual intercourse – stimulation of oxytocin release and prostaglandins
Uncertain role, but fun to try.
Breast stimulation
May be helpful but no good evidence
Acupuncture/transcutaneous nerve stimulation
May have benefit, need better studies
Tenore, JL. Methods for cervical ripening and induction of labor. AFP 2003.

21. Labor Induction
Stimulating uterine contractions to promote delivery prior to the onset of spontaneous active labor
Rate is > 20% and increasing
Most common indication is postterm pregnancy

22. Risks of Labor Induction
Operative vaginal delivery
Cesarean delivery
Excessive uterine activity with abnormal FHR patterns (uterine hyperstimulation)
Delivery of preterm infant

23. Labor Induction - ACOG
PGE analogues are effective for both cervical ripening and labor induction (Level A)
Cytotec at doses of 25 micrograms every 3-6 hours are effective for cervical ripening and labor induction (Level A)
With term PROM, may induce labor with prostaglandins (Level A)
Increased complications with doses of cytotec > 50 mcg (Level B)
Avoid cytotec in VBAC (Level B)

24. Methods of Labor Induction
Oxytocin
Oxytocin receptors in the uterus increase starting at 32 weeks
IV administration of solution of 10 Units to 1 Liter of isotonic solution = 10 mU/1mL
Continuous infusion vs. pulsed dosing
Continuous usually start at 0.5 to 2.5 mU/min increased by same increment every minutes
Effect within 3-5 minutes, steady state by min.
No clearly superior regimen – great variability in response

25. Methods of Labor Induction
PGE1
PGE2
Oxytocin

26. Oxytocin continued Oxytocin is good… It is potent May titrate
Short half-life
Well tolerated

27. Oxytocin for labor induction
Low-dose
Start at mU/min
Increase by 1-2 mU/min every minutes
High-dose
Start at 6-8 mU/min
Increase by 6 mU/min every minutes
High-dose results in shorter labor, decreased intra-amniotic infections, and decreased rates of c/section for dystocia but higher risk of hyperstimulation
Sanchez-Ramos L. Induction of labor. Obstet Gynecol Clin North Am - 01-JUN-2005; 32(2): , viii

28. Dosing of Oxytocin
Commonly accepted practice is to increase by 1-2 mU/min every 40 minutes
May optimize pharmacokinetics by not increasing dose before steady-state is reached
Lower risk of hyperstimulation
May result in longer labor for oxytocin-insensitive women
May result in lower overall dose of oxytocin required
Usual dose
More than 90% of women will respond to 16 mU/min or less
Rare for women to require mU/min

29. Potential Risks Stripping membranes Nipple stimulation Amniotomy
Bleeding from undiagnosed placenta previa or low-lying placenta
Accidental amniotomy
Nipple stimulation
Uterine hyperactivity
FHR decels
Amniotomy
Unpredictable length of time until onset of contractions
Cord prolapse
Chorioamnionitis
Cord compression
Vasa previa rupture
Laminaria
Increased maternal/fetal infections
ACOG Practice Guideline No Induction of labor.

30. Potential Risks cont’d
Misoprostol (cytotec)
Tachysystole, hyperstimulation
Uterine rupture
Increase in meconium staining of AF
Abnl FHR tracing
Likely dose and route dependent
Intravaginal/intracervical PGE2
1-5% rate of uterine hyperstimulation
Fever, vomiting, diarrhea
Uterine rupture secondary to hyperstimulation
Oxytocin
Dose related
Hyperstimulation
FHR decels
Placental abruption/uterine rupture secondary to hyperstim
Water intoxication
Antidiuretic effect and hypotension with large/rapid IV administration
ACOG Practice Guideline No Induction of labor.

31. Questions & Comments

32. References ACOG Practice Bulletin No 10 Induction of Labor, 1999.
Crane JM. Factors predicting labor induction success: A critical analysis 2006; Clin Obstet Gynecol 49;
Harman JH, Kim A. Current trends in cervical ripening and labor induction. AFP 1999;60:
Tenore JL. Methods for cervical ripening and induction of labor. AFP 2003;67:
Weeks A. Oral misoprostol administration for labor induction. Clin Obstet Gynecol 2006;49: