1. Cervical Ripening and Induction/Augmentation of Labor
Daren Sachet, RNC/MPA

2. Objectives
List the indications and contraindications for cervical ripening and induction of labor.
Discuss the different methods used for cervical ripening, labor induction and augmentation.
Discuss the nurses role in the safe administration of cervical ripening and induction agents.

3. Definitions What is cervical ripening? What is induction?
Preparation of an unfavorable cervix for labor induction
What is induction?
Stimulation of uterine contractions before the spontaneous onset of labor
What is augmentation?
Correcting ineffective uterine contractions or hypocontractility

4. Incidence in the United States
National Center for Health Statistics (NCHS) year 2000 data
Induction of labor- 19.9%
labor augmentation-17.9%
National Center for Health Statistics (NCHS) year 2009 data
Induction of labor %
Labor augmentation %
Since 1989, this represents a 137% increase in induction and a 75% increase in augmentation rates.
NCHS, 2009

5. Risk-Benefit Risk of Cesarean Birth for Nulliparous Women:
17.2% spontaneous labor
30.4% induced labor
77.7% increase for induction
Reisner et al., 2009
Use of pharmacologic agents increases risk for tachysystole, indeterminate or abnormal FHR patterns and failure to progress

6. Cascade of Interventions Related to Induction of LaborIV
Bedrest
Continuous EFM
Amniotomy
Significant Pain
Epidural
Prolonged Labor
Simpson, 2009

7. Economic Costs Spontaneous Labor/vaginal birth $4000
Induction of labor/vaginal birth
$5000
Cesarean Birth/scheduled
$7000
Cesarean Birth/failed induction
$7500
Simpson, KR., 2009
Simpson, 2009

8. Indeterminate/Abnormal FHR (Category II and Category III FHR)
Nearly twice the risk, possibly related to:
Tachysystole
Early Amniotomy
Labor Dystocia
Longer Labor
Less Fetal Tolerance
Glantz, 2005, Simpson, KR., 2009

9. Risks to the Infant Respiratory Distress Syndrome TTN Hypoglycemia
Sepsis
Admission to higher level of nursery care
> LOS
Tita, 2007

10. Indications for Cervical Ripening and Induction of Labor
Medical
Premature rupture of membranes, post term pregnancy, preeclampsia, hypertension of various types including transient, diabetes or abnormal GTT, fetal compromise, coagulation issues, multiple gestation, suspected fetal disease/compromise, fetal death, polyor oligo, poor fetal growth, infection, etc. Table Number 11.07: Conditions Possibly Justifying Elective Delivery Prior to 39 Weeks Gestation (Ver. 2011A) Code ICD-9-CM Description Shortened Description
Induction without a medical indication is discouraged but according to ACOG, labor may be induced for logistic or “psychosocial indications”.
It is not recommended to induce these patients until 39 weeks and should only be undertaken after fully informing the woman of potential risks involved.
Joint Commission Perinatal Care Quality Measure Decrease the rate of women with elective delivery at weeks.
JC 2010
Decrease the rate in patients with elective delivery at 37 to 39 weeks gestation.
Joint Commission National Quality Core Measure PC-01

11. Contraindications-Induction of Labor
Generally, the contraindications for labor induction are the same as those for spontaneous labor and vaginal birth
Vasa previa or complete placenta previa
Transverse fetal lie
Umbilical cord prolapse
Previous transfundal uterine incision
Active genital herpes infection
Pelvic structural deformities
Invasive cervical cancer

12. Situations Requiring Special Attention
One or more previous low-transverse cesarean births
Breech presentation
Maternal heart disease
Multifetal pregnancy
Polyhydramnios
Presenting part above the pelvic inlet
Severe hypertension
Abnormal FHR patterns requiring emergent birth
A trial of labor after a previous cesarean birth or history of prior uterine scar
ACOG 2009, 2002

13. Indications for Augmentation of Labor
Dystocia
Uterine Hypocontractility
Uterine hypocontractility should be augmented only after both the maternal pelvis and fetal presentation have been assessed.
ACOG 2009

14. Pre-induction/Ripening Criteria
Availability of trained nursing and provider staff
Cervical ripening agents should be administered at or near the labor and birth suite where uterine activity and FHR can be monitored continually
Assessment of gestational age, cervical status, pelvic adequacy, fetal size and presentation
A physician capable of performing a cesarean birth should be readily available.
ACOG 2009
A physician capable of performing a cesarean birth should be readily available.

15. Criteria continued Considerations to any risks to mother or fetus
Patient counseling regarding indications, agents/methods, and possibility of repeat induction or cesarean birth
The medical record should document that a discussion was held between the pregnant woman and her health care provider
ACOG 2009

16. Bishop Score Has been shown to be an important determinant of the success or failure of induction
Dilate cm
Efface%
Station
Consistency
Pos Cx
Closed
0-30 -3
Firm
Post 1
1-2
40-50 -2
Med
mid 2
3-4
60-70
-1/0
Soft
Ant 3
5-6 80
+1/+2
___
Cervical status is the most important factor predicting the success of induction of labor
Bishop score>5 multips or >7 primips, increases success of induction. If less consider ripening first
Jennifer:
Cx :closed 0
Eff:50% 1
Sta:-2 1
Consistency: med 1
Position cx: post 0
_________
Bishop Score: 3
Sarah
Cx :1 1
Eff:70% 2
Sta:-2 1
Consistency: med 1
Position cx: ant 2 7

17. Cervical Status
Includes documentation of the Bishop score and the presence or absence of uterine activity
For women at term, a Bishop score of 6 or more may be useful in predicting onset of spontaneous labor within 7 days
Rozenberg, Goffinet & Hessabi, 2000

18. Cervical Ripening Agents
These agents may soften the cervix, change the Bishop score
Mechanical/Non pharmacologic Methods
Laminaria tents
Synthetic hygroscopic dilators (Lamicel and Dilapan)
Balloon catheters
Pharmacologic Methods
Prostaglandins (E1 & E2)
Oxytocin

19. Synthetic Osmotic Dilators
Mechanical Dilators
Laminaria Tents
Synthetic Osmotic Dilators
Cervical Ripening Balloons
All mechanical Devices are Placed in endocervical canal under direct visualization using aseptic technique Inserted by provider
May be appropriate for women for whom pharmacologic agents for cervical ripening are contraindicated
Who might these patient’s be? Too many contractions-

20. Laminaria Tents Stems of cold water seaweed
Available in various sizes from 2-6mm in diameter and 60mm in length
Absorb fluid from the cervical tissues
Swell two to three times diameter in 6-12 hours
Cause mechanical dilation and local prostaglandin release

21. Synthetic Osmotic Dilators
Lamicel
Dilapan
Polyvinyl alcohol polymer sponge soaked in 450 mg of magnesium sulfate
Absorb fluid from cervical tissues
Swell to 3-4 times diameter in 2-4 hours
Multiple serial applications possible
Cause mechanical dilation and local prostaglandin release

22. Balloon Catheters and Extraamniotic Saline Infusion
Foley Catheter
Extraamniotic saline infusion- balloon catheter
Double Balloon Cervical Ripening Catheter
Results seen within 8-12 hours after insertion
Next slide for details

23. Mechanical Ripening Devices
Double balloon device
Foley catheter
Foley
flush g indwelling urinary (Foley) catheter with sterile NS prior to insertion.
Practitioner places it in cervical canal above internal cervical os.
catheter balloon inflated above internal os with 30-40ml of sterile normal saline
Some places put NS in the collection bag to add traction, others just tape the tubing to the mother’s leg to supply traction. Foley catheter: Clamp tubing and tape to Mom’s leg, unless extraamniotic infusion of NS will occur.
Extraamniotic Saline Infusion or Prostin E2 infusion:
22 gauge foley inserted through external cervical os. Balloon inflated with 30 cc sterile water.
The saline or PGE2 solution is infused through the catheter port at a constant rate by infusion pump. with normal saline infusion at 1 ml/min (60ml/hr) into extraamniotic space.
Fluid allowed to spill out of vaginal
Every hour RN checks for balloon displacement with a gentle tug.
Cause direct pressure and overstretching of the lower uterine segment and cervix as well as local prostaglandin release
Maximum time of 12 hours or when SROM or spontaneous expulsion (8-12 hr average)
Double balloon catheters
Insert into cervix until both balloons have advanced into the cervical canal.
Place 40 mL NS in balloon port marked U (uterus), tug to bring it up against the os and the other balloon will become visible in the vagina.
Fill balloon port marked V(vagina) with 20 mL NS. May tape extended tubing to Mom’s leg.
Add additional 20 mL NS at a time to each balloon for a total of 80 mL in each balloon.
Do not leave in place for more than 12 hours.
Remove if SROM while in place.

24. Pharmacologic Methods Not recommended for use in women with history prior c-birth or uterine scar
Prostaglandin E1: Misoprostol (Cytotec)
Oral, sublingual or vaginal use
Wide variations exist in time of onset of uterine contractions
Peak action is approximately 1-2 hours but can be up to 4-6 hours
Available in 100 mcg & 200 mcg tablets. 100mcg tablet is not scored; dose should be prepared by pharmacy, not cut by the nurse.
Vaginal 25 mcg inserted into posterior vaginal fornix and repeated every 3-6 hours up to 6 doses in 24 hours for vaginal route. Maximum of 150 mcg/24hr
Oral mcg orally Reduces the need for repeated vaginal exams
Is effective at achieving vaginal delivery although not as quickly as vaginal placement
Rates of tachysystole are lower when using comparable doses
Oral dose may need 50 mcg though most protocols call for 25 mcg to start
Weeks & Alfirevic, 2006
Wide variation in onset of uterine ctx’s. Peak action is approximately 1-2 hours when administered intravaginally, but can be up to 4 to 6 hours for some women.

25. Re-dosing Parameters Re-dosing is permissible if: Still unripe cervix?
Happy baby?
Redosing is withheld if:
Redosing is permissible if:
Redose if:
Cervical condition remains unfavorable
Uterine activity is minimal
FHR is reassuring
It has been at least 3 hours since last dose
Withheld if:
There are two or more contractions in 10 minutes
Adequate cervical ripening is achieved (Bishop score of 8 or greater)
Patient enters active labor
FHR is indeterminate or abnormal
ACOG, 1999

26. Complications with Misoprostol (Cytotech)
Tachysystole
Indeterminate/Abnormal FHR pattern
Precipitous Labors
Uterine Rupture
Need careful maternal/fetal assessments
Need consent/protocols
ACOG, 2009

27. Prostaglandin E2-Dinoprostone
Prepidil
Perform speculum exam, introduce gel just below cervical os
Patient should remain recumbent for at least 30 minutes
Uterine contractions usually occur within one hour of administration- peak activity within 4 h
Gel is introduced into the cervical canal just below the internal os with a catheter provided in the kit. If cervix not effaced, use 20 mm shielded endocervical catheter
If cervix is > or = 50% effaced, use 10 mm catheter
Storage and Preparation- store in refer (stable up to 2 years when stored at 2-8 degrees C)
Bring to room temperature just before administration. Do not use warm water bath or microwave as heat may cause inactivation
Uterine ctx’s usually occur within one hour of administration
Peak activity occurs within four hours
If no response, increase dose by 0.5 mg every 6 hours (comes in 0.5 mg PGE2 to a 3 gram syringe)
Maximum cumulative dose is 1.5 mg (three doses) over 24 h.
Rate of tachysystole is 1-5% usually occurs within one hour of administration

28. Prostaglandin E2-Dinoprostone
Cervidil
Controlled-release vaginal insert with removable cord is easy to administer and does not require speculum exam
Keep frozen until immediately before use, no warming required
Patient should remain supine for 2 hours following insertion- then can ambulate if EFM telemetry available
Uterine contractions usually occur within 5-7 hours
Remove after 12 h or at onset of labor
Rate of tachysystole is about 5%; usually occurs within 1 h of administration but may occur up to 9.5 h after administration
Not appropriate for outpatient cervical ripening
ACOG, 1999a; Rayburn et al.,2000)

29. Cervical Ripening Agents
Minimum safe interval from prostaglandin to oxytocin administration not established
Manufacturers guidelines recommend
Misoprostol- at least 4 hours after last dose
Prepidil hours after last dose
Cervidil minutes after removal of vaginal insert
Not contraindicated with PROM

30. Induction and Augmentation of Labor
Mechanical methods of Induction of Labor
Stripping the Membranes
Digital separation of the chorioamnionic membrane from the wall of the cervix and lower uterine segment during a vaginal examination (aka sweeping the membranes)
A finger is inserted into the cervical os and rotated 360 degrees.
Exact mechanism is unknown- thought to release prostaglandins locally from the amnion/chorion/decidua
Risks include the potential for intraamniotic infection, unplanned rupture of membranes, disruption of an undiagnosed placenta previa and precipitous labor and birth
ACOG, 1999a; Hadi, 2000

31. Amniotomy Artificial rupture of membranes
NURSES DO NOT PERFORM AMNIOTOMY
Successful in multiparous women with cervical dilation of greater than 2 cm
May preclude need for oxytocin
Early amniotomy contraindicated when maternal infection is present (HIV, active herpes simplex)
AWHONN, 2002
Newer literature states early amniotomy markedly increases the risk for cesarean birth and may only decrease length of labor by 1-2 hours
Simpson & Thorman, 2005
Risks of amniotomy:
Umbilical cord prolapse
Intraamniotic infection
Fetal injury
Bleeding from an undiagnosed vasa previa
Commitment to labor with an uncertain outcome
Documentation & amniotomy
Medical record documentation should include the indication for amniotomy
Amount,color and odor of amniotic fluid
Characteristics of the FHR before amniotomy
Fetal response following the procedure
Cervical status and fetal station

32. Oxytocin
Most commonly used induction agent in the United States and worldwide
Kelly & Tan, 2001
Synthetic oxytocin is chemically and physiologically identical to endogenous oxytocin
Half life between minutes
Dawood, 1995a; Arias, 2000
3 – 4 half-lives to reach steady state
Full effects of oxytocin cannot be determined until steady-state concentration has been achieved.
Physiologic steady state 40 min, basis for dosing interval.
Pitocin Pit Vitamin P

33. Endogenous Oxytocin First Stage Labor
Maternal circulating concentration 2-4 mU/min
Fetal Contribution
3 mU/min
Combined effects = 5-7 mU/min
Second Stage Labor
Surge of oxytocin at Ferguson’s reflex
Simpson, KR, 2009

34. Response to Oxytocin
Oxytocin receptor sites decrease significantly during prolonged exposure to oxytocin for induction/augmentation compared with spontaneous labor
Desensitization is related to dose rate and length of administration
More oxytocin for dysfunctional labor will cause further desensitization, so you should give your patient a rest period of 1-2 hours.
Phaneuf et al., 2000
Continued oxytocin after active labor is established will not shorten labor. Active labor is self-sustaining.

35. Oxytocin Dosing
Considerable controversy exists about dosage and rate increase intervals-there is no consensus in the literature
Low dose regimes and less frequent increases in dose are associated with decreased uterine tachysystole
Higher doses and shorter intervals do not result in a clinically significant decrease in length of labor or in the rate of C/birth
ACOG, 2009
A cervical dilation rate of 0.5-1cm/h in the active phase of labor indicates that labor is progressing sufficiently and that oxytocin administration is adequate
AWHONN, 2002

36. Oxytocin Dosing Only increase oxytocin rate if: FHR is normal
Labor has not progressed cm/hr
Contractions are no closer than every 2-3 minutes
Excessive uterine activity over the course of 1 hour in first stage of labor is associated with an umbilical artery pH ≤ 7.11 at birth
Decrease or discontinue oxytocin in active labor
Simpson, KR, 2009

37. Physiologic Dosage Start with doses of 0.5-1 mU/min
Increase in 1-2 mU/min increments every 30-40minutes until contractions are every 2-3 minutes apart and labor is progressing ACOG, 1999a, SOGC, 2001
Current literature suggests that 90% of pregnant women at term will have labor successfully induced with 6mU/min or less of oxytocin
Dawood, 1995a, 1995b; Seitchik, Amico et al., 1984

38. Oxytocin Administration
No maximal dose of oxytocin has been firmly established
Doses above 40mU/min are rarely used, except in cases of intrauterine fetal demise (IUFD).
Infusion rates >=20mU/min can decrease free water clearance by the kidney resulting in water intoxication.
Smith and Merrill, 2006
Many policies require a bedside evaluation by the LIP if oxytocin is to exceed 20 mu/min.

39. High Dose Oxytocin
According to ACOG (2009), protocols that involve “high-dose” oxytocin are acceptable; however, high-dose oxytocin is associated with more uterine tachysystole
SOGC recommends using the minimum dose to achieve active labor, increasing the dosage no more frequently than every 30 minutes and reevaluating the clinical situation if the oxytocin dosage rate reaches 20 mU/min
High dose oxytocin protocols seem to have the advantage of decreasing the length of labor somewhat, compared with low-dose protocols. It does not appear to decrease C/S rates. Not harmful but more tachysystole.
Original study called active management of labor
Nullip in active labor, singleton, vtx, reassuring
1:1 RN
Amniotomy
If no labor then start pit at 6 mu/min, increase by 6 to achieve adequate labor
Avoid more than 7 contr in 15 min.

40. Oxytocin and Medication Safety
August 2007 the Institute for Safe Medication Practices added oxytocin to the High Alert Medication list. There are only 10 others on the list.
Joint Commission Standard MM.7.10
The organization develops processes for managing high-risk or high-alert medications
The organization must develop additional processes for selecting, procuring, storing, ordering, transcribing, preparing, dispensing, administering and monitoring these high-risk or high-alert medications.
Some safe practices:
Use IV pumps, preferably with a drug library feature, never free flow for labor.
Oxytocin is never hung as the primary line in labor. It must be a secondary line piggybacked into the main line at the port closest to the IV site
Use only premixed, standard concentrations
Label clearly
Consider using a concentration that gives a 1/1 ratio. For example, add 15 units to 250 mL of fluid or 30 units to 500 mL

41. Nursing responsibilities
Titrate oxytocin infusion drip to achieve three contractions in 10 minutes with a duration of seconds
Closely monitor fetal response, uterine activity and resting tone
Monitor maternal vital signs and fluid balance
Closely monitor mean with dose changes, assess every 15 min. If a nurse cannot clinically evaluate the effects of medication at least every 15 minutes (AAP7ACOG, 2007) the oxytocin infusion should be discontinued until this level of maternal and fetal care can be provided (AWHONN Simpson, 2009) and Guidelines for Perinatal Care.
Staffing Guidelines for women receiving oxytocin should be 1:1 care during induction/augmentation. Be sure to document every 15 minutes, and whenever you change the rate, at the least. (Guidelines for Professional Registered Nurse Staffing for Perinatal Units, AWHONN, 2010)

42. Potential Complications-Oxytocin
Tachysystole
Abruptio placentae
Uterine rupture
Hyponatremia (water intoxicaiton)
Tachysystole (as defined by NICHD 2008)
>5 contractions in 10 minutes, averaged over a 30-minute window. Tachysystole should always be qualified as to the presence or absence of associated FHR decelerations.
Hyponatremia:
When infused in high doses, oxytocin infusion rate ≥ 20 mU/min over time, there is a potential for oxytocin cross-reactivity with the vasopressin receptor located in the kidney as oxytocin is similar in structure to vasopressin (antidiuretic hormone). Activation of vasopressin receptor results in water retention and a dilutional hyponatremia.
Isotonic solution recommended
S/S
Confusion
Convulsions
Coma
Congestive heart failure
Death
Strict monitoring of I/O’s recommended

43. Nursing Interventions for Tachysystole with Normal FHR pattern
Lateral positioning of mother
Increase IV fluid (LR)
If uterine activity not returned to normal after 10 minutes,  oxytocin by half
If tachysystole persists, D/C oxytocin until tachysystole resolves
Consider terbutaline 0.25 mg SQ, with order
ACOG, 2010, AWHONN, 2008

44. Nursing Interventions for Tachysystole with Indeterminate or Abnormal FHR pattern
Discontinue or reduce oxytocin
Lateral positioning of Mother
IV fluid bolus (LR)
If hypotensive, (as with epidural) contact anesthesia provider, prepare to administer epinephrine, with order
Oxygen, 10 LPM, non-rebreather mask
Consider terbutaline 0.25 SQ, with order
If unresolved, inform provider immediately, possibly prepare for C/S.
(ACOG 2010)

45. Resuming Oxytocin Once uterine activity and FHR pattern are normal:
If oxytocin was discontinued >20-30 minutes, resume at no > ½ the rate that caused tachysystole. Gradually increase rate if needed based on protocol and maternal/fetal status
If oxytocin was discontinued >30-40 minutes resume at initial dose ordered

46. Women attempting VBAC
Should women with a previous cesarean birth undergo induction or augmentation of labor?
Spontaneous labor more likely to result in successful VBAC
Some studies show women with oxytocin administration undergoing TOLAC may be at increased risk of uterine rupture than spontaneous labor. Other studies have not.
Use of prostaglandins are associated with a higher rate of uterine rupture and are NOT RECOMMENDED
ACOG, 2010
Increase in rupture may be more if woman has never had a vaginal birth before, if cervix is not ripe.

47. VBAC Success Rates
Study performed by the Maternal-Fetal Medicine Units Network – 4 year multicenter prospective observational study of 14,529 women undergoing trial of labor prior cesarean delivery.
Induced labor- 67% success rate
Augmented labor-74% success rate
Spontaneous labor-81% success rate
Smith & Merrill, 2006

48. VBAC Induction
Physician and surgical team must be immediately available throughout active labor
Recommend 1:1 nursing care with an experienced RN
Continuous EFM
Must have ability to perform emergency C/birth

49. Nursing Implications with VBAC Induction/Augmentation
Access to operating room readily available
Monitor as for high risk
Signs and symptoms of uterine rupture/dehiscence of prior scar
Patient c/o increasing pain and tenderness even with epidural
Presentation may take place over period of time or suddenly like “something has given away”
Vomiting, syncope, vaginal bleeding, tachycardia, fetal bradycardia or absent fetal heart rate
Internal VS external monitoring, either OK, evidence suggests that IUPC does not assist in the dx of uterine rupture (ACOG 2010 bulletin 115), however FSE may be useful because acute signs include fetal bradycardia, abnormal FHR pattern

50. Management Maternal stabilization and immediate cesarean birth
Key to diagnosis is suspicion of uterine rupture
Simpson, K.R & Creehan, P., 2001

51. Conflict? No way! Common reasons for response
Areas for conflict:
Interpreting FHR patterns
How to treat indeterminate and abnormal FHR patterns
How to respond to tachysystole
Common responses
Avoid
Work Around
Going along to get along
Deception
Stress/Anxiety
Simpson, KR., 2009
Common reasons for response
Disrespectful or disruptive clinical behavior
Intimidation, belittling, yelling, temper tantrum, nonverbal devaluation such as eye rolling, sighing, etc
Lack of administrative response when reporting behaviors
Fear of relatiation
Repeat reporting but no apparent action or change in behavior

52. Summary
Evidence suggests that cervical ripening can increase the chances of successful induction
Misoprostol (cytotec) is becoming more widely used for cervical ripening and labor induction
No elective inductions before 39 completed weeks of gestation
Protocols should be based on ACOG/AHWONN standards and guidelines
Multiple factors contribute to the steady increase in the rate of induction in the United States
Consider implementation of an Induction of Labor Patient Safety Bundle.
Consider implementation of an induction of labor safety Bundle include:
Staff & Medical Staff education (everyone on the same page)
Policies
Order sets
Consent
Information for the patient re scheduling procedures
Pre-induction checklist
In-use checklist

53. References
American Academy of Pediatrics & American College of Obstetricians and Gynecologists. (2007). Guidelines for Perinatal Care (6th Ed.). Elk Grove, IL, Washington DC: Authors.
National Center for Health Statistics (NCHS) year data
American College of Obstetricians and Gynecologists. (August, 2009). Induction of Labor, Practice Bulletin, Clinical Management Guidelines for Obstetrician-Gynecologists, Number107. Washington DC: Author.
American College of Obstetricians and Gynecologists. (November, 2010). Management of Intrapartum Fetal Heart Rate Tracings, Number116. Washington DC: Author.
American College of Obstetricians and Gynecologists. (August 2010).Vaginal Birth After Previous Cesarean Delivery, Practice Bulletin, Clinical Management Guidelines for Obstetrician-Gynecologists, Number115, Washington DC: Author.
Association of Women’s Health Obstetric and Neonatal Nurses. (2010). Guidelines for Professional Registered Nurse Staffing for Perinatal Units, Washington DC: Authors
Glantz, J (April 2005). Elective Induction vs. spontaneous labor Associations and Outcomes. Ele Med. 50(4):
International Classification of Diseases, Code ICD-9-CM Description Shortened Description Table Number 11.07: Conditions Possibly Justifying Elective Delivery Prior to 39 Weeks Gestation (Ver. 2011A)
Joint Commission. (2010). Specifications Manual for Joint Commission Quality Core Measures
Phaneuf S., et al, Loss of myometrial oxytocin receptors during oxytocin-induced and oxytocin-augmented labour. Journal of Reproduction & Fertility 2000;120(1):91-97.
Simpson, K.R., (2008). Cervical Ripening and Induction and Augmentation of Labor. 3rd edition. Association of Women’s Health, Obstetric and Neonatal Nurses. Washington DC.
Tita, A.,et al. (2009). Timing of elective preterm and neonatal outcomes. (Electronic Version). NEJM. 360:2,