Labor induction

Labor induction
Intervention
ICD-9-CM	73.0-73.1

Labor induction is artificially stimulating childbirth.

Medical uses

Commonly accepted medical reasons for induction include:

• Postterm pregnancy, i.e. if the pregnancy has gone past the end of the 41st week.
• Intrauterine fetal growth restriction (IUGR).
• There are health risks to the woman in continuing the pregnancy (e.g. she has pre-eclampsia).
• Premature rupture of the membranes (PROM); this is when the membranes have ruptured, but labor does not start within a specific amount of time.^[1]
• Premature termination of the pregnancy (abortion).
• Fetal death in utero and previous history of stillbirth.
• Twin pregnancy continuing beyond 38 weeks.
• Previous health conditions that puts risk on the woman and/or her child such as diabetes, high blood pressure

Induction of labor in those who are either at or after term improves outcomes for the baby and decreases the number of C-sections performed.^[2]

Methods of induction

Methods of inducing labor include both pharmacological medication and mechanical or physical approaches.

Mechanical and physical approaches can include artificial rupture of membranes or membrane sweeping. The use of intrauterine catheters are also indicated. These work by compressing the cervix mechanically to generate release on prostaglandins in local tissues. There is no direct effect on the uterus.

Pharmacological methods are mainly using either dinoprostone (prostaglandin E2) or misoprostol (a prostaglandin E1 analogue)

Medication

• Intravaginal, endocervical or extra-amniotic administration of prostaglandin, such as dinoprostone or misoprostol.^[3] Prostaglandin E2 is the most studied compound and with most evidence behind it. A range of different dosage forms are available with a variety of routes possible. The use of misoprostol has been extensively studied but normally in small, poorly defined studies. Only a very few countries have approved misoprostol for use in induction of labor.
• Intravenous administration of synthetic oxytocin preparations. A high dose does not seem to have greater benefits than a standard dose.^[4]
• Use of mifepristone has been described but is rarely used in practice.^[5]
• Relaxin has been investigated,^[6] but is not currently commonly used.
• mnemonic; ARNOP: Antiprogesterone, relaxin, nitric oxide donors, oxytocin, prostaglandins

Mechanical and physical approaches

• "Membrane sweep", also known as membrane stripping, or "stretch and sweep" in Australia and the UK – during an internal examination, the practitioner moves their finger around the cervix to stimulate and/or separate the membranes around the baby from the cervix. This causes a release of prostaglandins which can help to kick-start labor.
• Artificial rupture of the membranes (AROM or ARM) ("breaking the waters")
• Extra-amniotic saline infusion (EASI),^[7] in which a Foley catheter is inserted into the cervix and the distal portion expanded to dilate it and to release prostaglandins.

When to induce

The American Congress of Obstetricians and Gynecologists has recommended against elective induction before 41 weeks if there is no medical indication and the cervix is unfavorable.^[8] However, recent studies contradict this view. One recent study indicates that labor induction at term or post-term reduces the rate of caesarean section by 12%, and also reduces fetal death.^[9] On the other hand, observational/retrospective studies have shown that non-indicated, elective inductions before the 41st week of gestation are associated with an increased risk of requiring a caesarean section.^[8] Randomized clinical trials have not been used to study this question. However, it has been found that multiparous women who are undergo labor induction without medical indicators are not predisposed to cesarean sections.^[10] Doctors and patients should have a discussion of risks and benefits when considering an induction of labor in the absence of an accepted medical indiction.^[8]

Studies have shown a slight increase in risk of infant mortality for births in the 41st and particularly 42nd week of gestation, as well as a higher risk of injury to the mother and child.^[11] Due to the increasing risks of advanced gestation, induction appears to reduce the risk for cesarean delivery after 41 weeks gestation and possibly earlier.^[9][12]

Inducing labor before 39 weeks in the absence of a medical indication, like hypertension, IUGR, or pre-eclampsia, increases the risk of complications of prematurity including difficulties with respiration, infection, feeding, jaundice, neonatal intensive care unit admissions, and perinatal death.^[13]

The odds of having a vaginal delivery after labor induction are assessed by a "Bishop Score". However, recent research has questioned the relationship between the Bishop score and a successful induction, finding that a poor Bishop score actually may improve the chance for a vaginal delivery after induction.^[9] A Bishop Score is done to assess the progression of the cervix prior to an induction. In order to do this, the cervix must be checked to see how much it has effaced, thinned out, and how far dilated it is. The score goes by a points system depending on five factors. Each factor is scored on a scale of either 0-2 or 0–3, any score that adds up to be less than 5 holds a higher risk of delivering by cesarean section.^[14]

Criticisms of induction

Induced labor may be more painful for the woman.^[15] This can lead to the increased use of analgesics and other pain-relieving pharmaceuticals.^[16] These interventions have been said to lead to an increased likelihood of caesarean section delivery for the baby.^[17] However, studies into this matter show differing results. One study indicated that while overall caesarean section rates from 1990–1997 remained at or below 20%, elective induction was associated with a doubling of the rate of caesarean section .^[18] Another study showed that elective induction in women who were not post-term increased a woman's chance of a C-section by two to three times.^[19] A more recent study indicated that induction may increase the risk of caesarean section if performed before the 40th week of gestation, but it has no effect or actually lowers the risk if performed after the 40th week.^[20][21]

The most recent reviews on the subject of induction and its effect on Cesaerean section indicate that there is no increase with induction and in fact there can be a reduction.^[9][22]

See also

• Tocolytics, labor repressants

References

1. Allahyar,J. & Galan, H. "Premature Rupture of the Membranes."; also American College of Obstetrics and Gynecologists.
2. Mishanina, E; Rogozinska, E; Thatthi, T; Uddin-Khan, R; Khan, KS; Meads, C (Jun 10, 2014). "Use of labour induction and risk of cesarean delivery: a systematic review and meta-analysis.". CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne 186 (9): 665–73. doi:10.1503/cmaj.130925. PMID 24778358.
3. Li XM, Wan J, Xu CF, Zhang Y, Fang L, Shi ZJ, Li K (March 2004). "Misoprostol in labor induction of term pregnancy: a meta-analysis". Chin Med J (Engl) 117 (3): 449–52. PMID 15043790.
4. Budden, A; Chen, LJ; Henry, A (Oct 9, 2014). "High-dose versus low-dose oxytocin infusion regimens for induction of labour at term.". The Cochrane database of systematic reviews 10: CD009701. doi:10.1002/14651858.CD009701.pub2. PMID 25300173.
5. Clark K, Ji H, Feltovich H, Janowski J, Carroll C, Chien EK (May 2006). "Mifepristone-induced cervical ripening: structural, biomechanical, and molecular events". Am. J. Obstet. Gynecol. 194 (5): 1391–8. doi:10.1016/j.ajog.2005.11.026. PMID 16647925.
6. Kelly AJ, Kavanagh J, Thomas J (2001). "Relaxin for cervical ripening and induction of labor". Cochrane Database Syst Rev (2): CD003103. doi:10.1002/14651858.CD003103. PMID 11406079.
7. Guinn, D. A.; Davies, J. K.; Jones, R. O.; Sullivan, L.; Wolf, D. (2004). "Labor induction in women with an unfavorable Bishop score: Randomized controlled trial of intrauterine Foley catheter with concurrent oxytocin infusion versus Foley catheter with extra-amniotic saline infusion with concurrent oxytocin infusion". American Journal of Obstetrics and Gynecology 191 (1): 225–229. doi:10.1016/j.ajog.2003.12.039. PMID 15295370.
8. American Congress of Obstetricians and Gynecologists, "Five Things Physicians and Patients Should Question", Choosing Wisely: an initiative of the ABIM Foundation (American Congress of Obstetricians and Gynecologists), retrieved August 1, 2013, which cites
   • American Academy of Pediatrics; American College of Obstetricians and Gynecologists. Guidelines for perinatal care (7th ed.). Elk Grove Village, IL: American Academy of Pediatrics. ISBN 978-1581107340.
   • ACOG Committee on Practice Bulletins (2009). "ACOG Practice Bulletin No. 107: Induction of Labor". Obstetrics & Gynecology 114 (2, Part 1): 386–397. doi:10.1097/AOG.0b013e3181b48ef5. PMID 19623003.
9. Ekaterina Mishanina et al., "Use of labour induction and risk of cesarean delivery: a systematic review and meta-analysis", April 2014, Canadian Medical Association Journal,
10. Heinberg EM, Wood RA, Chambers RB. Elective induction of labor in multiparous women. Does it increase the risk of cesarean section? 2002. J Reprod Med. 47(5):399-403.
11. Tim A. Bruckner et al, Increased neonatal mortality among normal-weight births beyond 41 weeks of gestation in California, October 2008, American Journal of Obstetrics and Gynecology,
12. Caughey, AB; Sundaram, V; Kaimal, AJ; Gienger, A; Cheng, YW; McDonald, KM; Shaffer, BL; Owens, DK; Bravata, DM (Aug 18, 2009). "Systematic review: elective induction of labor versus expectant management of pregnancy.". Annals of Internal Medicine 151 (4): 252–63, W53–63. doi:10.7326/0003-4819-151-4-200908180-00007. PMID 19687492.
13. "Doctors To Pregnant Women: Wait At Least 39 Weeks". 2011-07-18. Retrieved 2011-08-20.
14. Doheny, K. (2010, June 22). Labor Induction May Boost C-Section Risk. HealthDay Consumer News Service. Retrieved from EBSCOhost.
15. National Institute for Health and Clinical Excellence, "CG70 Induction of labour: NICE guideline", July 2008, retrieved 2012-04-10
16. Vernon, David, Having a Great Birth in Australia, Australian College of Midwives, 2005, ISBN 0-9751674-3-X
17. Roberts Christine L, Tracy Sally, Peat Brian (2000). "Rates for obstetric intervention among private and public patients in Australia: population based descriptive study". British Medical Journal 321: 140.
18. Yeast John D (1999). "Induction of labor and the relationship to caesarean delivery: A review of 7001 consecutive inductions.". American Journal of Obstetrics and Gynecology.
19. Simpson Kathleen R., Thorman Kathleen E. (2005). "Obstetric 'Conveniences' Elective Induction of Labor, Cesarean Birth on Demand, and Other Potentially Unnecessary Interventions". Journal of Perinatal and Neonatal Nursing 19 (2): 134–44. doi:10.1097/00005237-200504000-00010.
20. Caughey AB, Nicholson JM, Cheng YW, Lyell DJ, Washington E. Induction of labor and caesarean delivery by gestational age. Am Journal of Obstetrics and Gynecology . 2006;195:700–5.
21. A Gülmezoglu et al, Induction of labor for improving birth outcomes for women at or beyond term,2009,The Cochrane Library,
22. Caughey A. (8 May 2013). "Induction of labour: does it increase the risk of cesarean delivery?". BJOG 121 (6): 658–661. doi:10.1111/1471-0528.12329.

External links

• Harman , Kim (1999). "Current Trends in Cervical Ripening and Labor Induction". American Family Physician 60: 477–84.
• Inducing Labor – WebMD.com
• Induction of labour. Clinical guideline, UK National Institute for Health and Clinical Excellence, June 2001.
• Josie L. Tenore: Methods for cervical ripening and induction of labor. American Family Physician, 15 May 2003.
• "Catecholamines – blood ." National Library of Medicine . N.p., n.d. Web. 28 Mar. 2011. <http://www.nlm.nih.gov/medlineplus>.