Labor induction

Labor induction
Intervention
ICD-9-CM	73.0-73.1

Labor induction is a method of artificially or prematurely stimulating childbirth in a woman.^[1]

Indications

Common suggested reasons for induction include:

• Postterm pregnancy, i.e. if the pregnancy has gone past the 42 week mark.
• Intrauterine fetal growth retardation (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.^[2]
• Premature termination of the pregnancy (abortion).
• Scheduling concerns.
• Fetal death in utero.
• Twin pregnancy continuing beyond 38 weeks.

Methods of induction

Methods of inducing labor include medication and processes.

If an induction causes complications during labor, a Caesarean section is almost always conducted. An induction is most likely to result in successful vaginal delivery when a woman is close to or in the early stages of labor. Signs of impending labor may include softening of the cervix, dilation and increasing frequency or intensity of contractions. The Bishop score may be used to assess the advisability of induction, and is based on such factors.

Medication

• Intravaginal, endocervical or extra-amniotic administration of prostaglandin, such as dinoprostone or misoprostol.^[3] In the few controlled trials that have been done, extra-amniotic administration appears to be more efficient than intravaginal or endocervical administration of prostaglandins in labor induction, with no differential effects on other outcome measures.^[4]
• Intravenous administration of synthetic oxytocin preparations, such as Pitocin.
• Natural Induction - Many midwives or other holistic providers practice "natural" induction, which may include use of herbs, castor oil or other medically unconventional agents to stimulate or advance a stalled labor.
• Use of mifepristone has been described.^[5]
• Relaxin has been investigated,^[6] but is not currently commonly used.

Processes

• "Membrane sweep", also known as membrane stripping, or "stretch and sweep" in Australia and the UK - during an internal examination, the midwife moves her 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")

When to induce

Until recently, the most common practice has been to induce labor by the end of the 42nd week of gestation. This practice is still very common. In the UK, a dating scan is usually conducted around the 12th week of pregnancy to determine the estimated due date. Research suggests that scans done after this date can cause the estimated due date to become less accurate, with the longer time that passes. In the cases of late dating scans, the estimated due date is less accurate which could therefore provoke a woman to be induced unnecessarily. While recent studies have shown a very slightly increased risk of infant mortality for births in 41st and particularly 42nd week of gestation, as well as a slightly higher risk of injury to the mother and child.^[7] The recommended date for induction of labor has therefore been moved to the end of the 41st week of gestation in many countries including Sweden and Canada.^{[citation needed]}

Inducing labor before 39 weeks increases the risk of complications and premature death, from factors including under-developed lungs, infection due to under-developed immune system, problems feeding due to under-developed brain, and jaundice from under-developed liver. Some hospitals in the United States noticed an significant increase in neonatal intensive care unit patients when women schedule deliveries for convenience, and are taking steps to reduce induction for non-medical reasons.^[8]

The odds of having a vaginal delivery after labor induction are assessed by a "Bishop Score". ^[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 open it is. The score goes by a points system depending on five factors. Each factor is scored on a scale between 0-3, any score that adds up to be less than 5 holds a higher risk of delivering by cesarean section. ^[10]

Criticisms of induction

Induced labor tends to be more intense and painful for the woman. This can lead to the increased use of analgesics and other pain-relieving pharmaceuticals.^[11] These interventions have been said to lead to an increased likelihood of caesarean section delivery for the baby.^[12] However, studies into this matter show differing results. One study indicated that while overall cesarean section rates from 1990-1997 remained at or below 20%, elective induction was associated with a doubling of the rate of caesarean section .^[13] Two more recent studies have shown 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.^[14][15] Research published in the Journal of Perinatal and Neonatal Nursing 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.^[16].

With early induction comes the increased risk of a caesarian section. A benefit to vaginal births are that the pressure of the birth canal helps squeeze out fluid from the babies lungs, which helps prevent Transient Tachypnea. ^[17].

See also

• Tocolytics, labor repressants

References

1. ^ Houghton Mifflin Company, (2006): The American Heritage Dictionary.
2. ^ Allahyar,J. & Galan, H. "Premature Rupture of the Membranes."; also American College of Obstetrics and Gynecologists.
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. ^ A Guide to Effective Care in Pregnancy and Childbirth. Murray Enkin, Marc J.N.C. Keirse, James Neilson, Caroline Crowther, Lelia Duley, Ellen Hodnett and Justus Hofmeyr. (Oxford University Press, 2000) [1] [2]
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. ^ 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, [3]
8. ^ "Doctors To Pregnant Women: Wait At Least 39 Weeks". 2011-07-18. http://www.npr.org/templates/transcript/transcript.php?storyId=138473097. Retrieved 2011-08-20. 
9. ^ Faulkner, J. (2008). The truth about induction. Fit Pregnancy, 15(2), 44-46. Retrieved from EBSCOhost.
10. ^ Doheny, K. (2010, June 22). Labor Induction May Boost C-Section Risk. HealthDay Consumer News Service. Retrieved from EBSCOhost.
11. ^ Vernon, David, Having a Great Birth in Australia, Australian College of Midwives, 2005, ISBN 0-9751674-3-X
12. ^ Roberts, Tracy, Peat, 2000 Rates for obstetric intervention among private and public patients in Australia: population based descriptive study Christine L Roberts, Sally Tracy, Brian Peat, "British Medical Journal", v321:140 July 2000
13. ^ Yeast, John D., Induction of labor and the relationship to caesarean delivery: A review of 7001 consecutive inductions., March 1999, American Journal of Obstetrics and Gynecology, [4]
14. ^ 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.[5]
15. ^ A Gülmezoglu et al, Induction of labor for improving birth outcomes for women at or beyond term,2009,The Cochrane Library, [6]
16. ^ Kathleen R. Simpson and Kathleen E. Thorman, "Obstetric 'Conveniences' Elective Induction of Labor, Cesarean Birth on Demand, and Other Potentially Unnecessary Interventions," Journal of Perinatal and Neonatal Nursing 19, no. 2 (2005):134-44
17. ^ Megerian, MD, PhD, FAAP, J. Thomas; et al. (September 2010). "Transient Tachypnea of Newborns". Langone Medical Center. EBSCO Publishing. http://www.med.nyu.edu/content?ChunkIID=102753. Retrieved 22 July 2011. 

External links

• Family.doctor.org
• Harman & Kim. "Current Trends in Cervical Ripening and Labor Induction" American Family Physician 1999; 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>.