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VBAC and Pharmaceutical Induction: Help or Hindrance?
by Jennifer Jamison Griebenow, ICAN of the Bluegrass

 

You are 38 weeks pregnant. You want a VBAC. Your care provider has agreed to your plans. Now he or she is suggesting that you should have an induction of labor in order to increase your chances of achieving a VBAC. Is this what you want to do?

 

Induction is medically indicated only if you or your baby have a specific health problem, such as diabetes mellitus or eclampsia. No study has ever shown that routine induction improves birth outcomes.¹  Unfortunately, despite the lack of compelling evidence of its benefits, induction has become common for mothers, VBAC and others alike. But induction is not a neutral option simply because its use is widespread in the United States. There are several reasons why its use may actually lead you into a repeat cesarean, instead of helping you to achieve a VBAC.

 

Rates of Cesarean

 

Studies show that, in general, induction increases the cesarean rate instead of lowering it. In a recent VBAC study utilizing data from 1997 through 1999, the rate of vaginal delivery was higher in the spontaneous delivery group than in the induced group. Only 50% of the inductions led to successful VBACs.²  In another study, the risk of experiencing a cesarean was 1.5 times higher for induced labors than for spontaneous labors.³  Inducing labor in a first VBAC attempt increases the repeat cesarean rate.⁴

 

Advantages to Spontaneous Labor

 

The body prepares for birth by releasing hormones, which loosen tissue and bone in the pelvis to prepare for birth. The production of these hormones increases dramatically just before natural labor begins. Pitocin and other induction agents cannot create this effect. Also, when in labor, it is most helpful to be able to move around freely and to feel that you can cope with the contractions. This type of labor situation is rarely possible with an induction because you are usually confined to bed and monitored. Many women find laboring on their backs in bed increases the pain they experience. Also, in this situation you do not have gravity working with you.

 

Furthermore, the proper positioning of the baby and its head is helpful to facilitate the birth. During the final weeks and days of pregnancy, the baby will usually assume the best position for birth. Starting labor before the baby is ready to go can possibly slow or stall the labor. Although birth is certainly possible when the baby’s head is asynclitic (tilted or turned toward one side instead of tucked), asyncliticism is another obstacle which it is preferable to avoid. Some care providers will ascertain your baby’s position and can adjust its head to facilitate its descent. However, not all are skilled at these adjustments or willing to do them. This positioning process works itself out in most labors that are not artificially stimulated. In an induction, this is not as likely to happen, due to all the factors mentioned above.

 

Risks of Induction

 

Another element of choosing induction is that, along with increasing the risk of having another cesarean, you increase the risks to yourself and your baby. The induction adds to the stress the baby experiences, increasing the risk of fetal distress, especially where higher doses of oxytocin or misoprostol are used.^5,6,7  You must be carefully monitored because induction can lead to overly strong contractions. Tetanic contractions are more difficult for you and your baby to cope with, as there is not as much time between them for the baby to receive oxygen. In some cases, induction leads to abruption of the placenta.^8,9

 

Choosing induction makes it more likely a mother will choose or require an epidural to deal with the contractions.^10,11  Epidurals add another tier of risks to the labor, including spinal headache, temporary urinary incontinence, maternal hypotension, and long-term backache, headache, migraines, and numbness or tingling; there are rare cases of cardiac arrest, convulsions, allergic shock and respiratory paralysis.¹²  Epidurals increase the mother’s temperature, which in turn raises the baby’s temperature, so that the baby may require interventions after birth to test for infection. Furthermore, epidurals can lead to fetal distress since the drugs used enter the baby’s system.¹³  Epidurals tend to slow labor, which could lead to another cesarean for "failure to progress,"¹⁴ and using them increases the probability that forceps will be used since the mother is less able to push well.¹⁵  If you should have a cesarean for a failed induction or "failure to progress," you will have experienced the side effects and risks of major surgery as well as those of the induction, all of which could possibly have been avoided.

 

AROM (artificial rupture of membranes) is not recommended for induction. Once the bag of water is broken, the risk of infection increases and time limits are imposed upon most labors. Statistically speaking, the use of AROM raises rather than lowers your chance of cesarean section.^16,17

 

Babies whose births are induced appear to have a higher risk of prematurity.¹⁸  Despite the use of tests and a physician’s best efforts, there is no complete guarantee of maturity. Also, babies whose births are induced more often experience resuscitation, admission to the intensive care unit, and phototherapy to treat jaundice, which all tend to require separation from the mother.¹⁹

 

"But What if the Baby is Too Big"

 

A major concern doctors and women may have is the size of the baby. When you want a VBAC, and the diagnosis from your previous cesarean was cephalopelvic disproportion (a macrosomic baby, and/or a small maternal pelvis), it is understandable that your doctor may think you should have an induction at 37, 38, or 39 weeks to "prevent the baby from getting too big." However, this belief is not supported by the medical evidence.

 

Part of the now-increasing cesarean rate includes cesareans that are done without attempting labor, even in first time mothers, because the doctor thinks the baby is too big. A recent study showed that the rate of induction among all expectant mothers increased from 12.9% in 1980 to 25.8% in 1995, and it is quite likely that this trend has increased since 1995. This includes an almost unbelievable 23-fold increase in induction for macrosomia.²⁰  While true cephalopelvic disproportion can exist, the diagnosis is very subjective and varies widely among different care providers.²¹

 

Ultrasounds are often used at or near term for size estimations. However, ultrasound screening can only reliably identify normal weight babies, not unusually large or small babies.²²  Women predicted to have large for gestational age babies have more cesareans simply because the ultrasound appears to show a large baby, whether the baby actually is large or not.²³  Clinical estimations of fetal size are slightly more accurate than ultrasound, so there is no reason to rely on the ultrasound estimate.²⁴

 

Induction for Large Babies

 

Induction does not improve outcomes for large babies. A 1997 study compared the cesarean rates between mothers induced for suspected macrosomic babies and mothers with large babies who started labor spontaneously. The authors were surprised to find that the cesarean rate in the induced group was 36% compared to 17% in the group which labored spontaneously; they expected the two groups to have similar rates. Furthermore, the babies in the induced group were actually somewhat smaller than those whose mothers who delivered spontaneously. The authors conclude, "An increased risk of cesarean delivery was observed in subjects undergoing induction for the indication of fetal macrosomia. These data support a plan of expectant management [waiting for labor to begin on its own] when fetal macrosomia is suspected."²⁵  A 1993 study found that fewer than half of the babies estimated to be over 4000 g actually were, and the researchers concluded that inducing for supposed macrosomia increased the cesarean rate and provided no benefits.²⁶

 

When fetal macrosomia was suspected prenatally, the cesarean rate was 52%, versus 30% in mothers in which fetal macrosomia occurred without being previously suspected. The higher cesarean rate was caused by the increased induction rate and failed inductions. So, prenatal prediction of fetal macrosomia increased the cesarean rate and did not decrease the rate of shoulder dystocia, a situation where the baby’s shoulders do not deliver spontaneously, the main concern physicians have with large babies. The conclusion: "Ultrasonography and labor induction for patients at risk for fetal macrosomia should be discouraged."²⁷

 

Premature Rupture of Membranes

 

If a mother’s amniotic sac ruptures first and she does not soon begin having productive contractions, most physicians say that she must be induced and have the baby within 24 hours, citing the risk of infection. However, it appears to be vaginal exams which introduce bacteria into the mother.²⁸  If a woman avoids any exams, does not insert anything into the vagina, and stays out of the hospital, she is not as likely to contract an infection. She can monitor her temperature to verify that there is no infection.

 

The rate of infant mortality and morbidity does not increase if you wait for labor to start on its own, although you may be in the hospital longer.²⁹  There is no significant difference in rates of infection or cesarean section whether you wait 24 hours or up to three days.³⁰  Some studies show an increased rate of operative delivery (cesarean or instrumental delivery) with induction, and no benefit to the fetus.³¹  "With expectant care about 70% of women will give birth within 24 hours and 85% within 48 hours. The majority of these women will derive little, if any, benefit from induction and a routine policy of induction of labor after PROM cannot be justified on the basis of the data that are available."³²

 

Going "Overdue"

 

Care providers may suggest or encourage induction of labor because a mother is past 40 weeks. However, medical evidence does not support induction if your pregnancy is postdates. Membrane sweeping has been shown in some studies to reduce the length of pregnancy,^33,34 but it is difficult to find current studies which address the outcomes for the fetus and the rates of cesarean section. In other words, membrane stripping does make the pregnancy shorter, but it does not necessarily lower your chance of a cesarean.

 

It is also wise to evaluate your due date. If your menstrual cycles are longer than 28 days, your pregnancies will necessarily be longer, because you did not ovulate and conceive until later in your cycle.

 

Risks of membrane stripping are infection, inadvertent rupture of the membranes, and problems due to an undiagnosed placenta previa.³⁵  While there is evidence that the risks for the baby increase somewhat after 41 or 42 weeks,^36,37 you still have to weigh the risks and benefits of the induction versus the risks of waiting for labor to begin spontaneously. "Postdates pregnancy is far from cut and dried. Testing in order to induce selectively introduces risks. Routinely inducing creates more problems than it solves. Letting nature take its course is generally best, although that is not risk free either. The reality is you pay your money and you take your choice."³⁸

 

Uterine Rupture

 

Finally, there is the issue of uterine rupture. The facts are clear: pharmaceutical induction increases the risk of uterine rupture.³⁹ The rate of rupture in a VBAC labor which is not induced is only 1/2 of one percent, less than your risk of experiencing several other major childbirth complications. However, when you add induction to the picture, the risks increase. A recent study which gained a great deal of media attention showed that in VBAC labors induced with Pitocin, the risk of rupture was .77%. With prostaglandin inductions, the rupture rate increased to 2.45%!⁴⁰

 

Almost every study verifies the risk of induction in VBACs, although some report no increase in rupture rate with induction.⁴¹ In a study which included 752 women, 12 uterine ruptures occurred, 11 of which were associated with the use of induction or augmentation or both. The authors stated that VBAC is safe, but VBAC with induction is not.⁴² In a study quoted above on the efficacy of induction, uterine scar separation was found to be 7% in the induced labors.⁴³

 

A review of almost 115,000 births in Canada confirmed that induction and augmentation of labor (using chemical agents to stimulate greater uterine activity in a labor which began on its own) are definite risk factors for uterine rupture.⁴⁴  Although augmentation of labor may be less questionable an option than induction because labor has already begun, the risk of rupture remains. A study from Israel concluded that using oxytocin and prostaglandin added to the risk of rupture.⁴⁵  Another study confirmed that spontaneous labors had a low (0.45%) risk of rupture, but that using prostaglandin gel increased the risk by 6.41 times.⁴⁶

 

Alternatives to Pharmaceutical Induction

 

Should one require an induction for a medical reason, what are the options? There are several options addressed, albeit briefly, in the medical literature. Sexual intercourse is cited by many midwives as effective, but there is little in the medical literature addressing its efficacy. Nipple or breast stimulation with an electric breast pump has been found to be as effective as oxytocin to start labor,⁴⁷ although it could have similar side effects and should be undertaken under the supervision of a provider experienced in it.

 

Acupuncture appears to increase the number of contractions.^48,49  Mechanical dilation, including the use of balloon catheters, is another non-pharmaceutical option that appears to be effective.^50,51  Using non-pharmaceutical forms of induction may have a higher failure rate than simply awaiting spontaneous labor if the baby is not ready to be born because it may not yet be positioned optimally, and without the bag of waters, may not be able to reposition. Data on the success of induction with non-pharmaceutical agents is difficult to come by. Should you wish to pursue information on the safety and efficacy of induction with these agents, and castor oil, cohoshes, and the like, you may refer, however, to the Midwife Archives at http://www.gentlebirth.org/archives/natinduc.html in order to make an informed decision.

 

Conclusion

 

In general, pharmaceutical induction as currently practiced in hospitals does not do what it promises. Instead of increasing your chances of a successful VBAC, it decreases them, and it does so at the same time that it makes your experience and your baby’s more dangerous. In case of medical need, induction can be a useful option, but it should not be chosen lightly. Should induction be required, it is important to ripen the cervix as much as possible before the induction to maximize your chances of success. Choose your care provider carefully and discuss your choices fully with him or her before you agree to induction of labor for a VBAC.

 

References
 

¹ Nichols CW. Postdate Pregnancy. Part I. A literature review. J Nurse-Midwifery 1985a;30(4)222-239.
² Sims EJ, Newman RB, Hulsey TC. Vaginal birth after cesarean: to induce or not to induce. Am J Obstet Gynecol 2001 May;184(6):1122-4.
³ Jarvelin MR, Hartikainen-Sorri AL, and Rantakallio P. Labour induction policy in hospitals of different levels of specialisation. Br J Obstet Gynaecol 1993;100(4):310-315.
⁴ Learman LA, Evertson LR, Shiboski S. Predictors of repeat cesarean delivery after trial of labor: do any exist? J Am Coll Surg. 1996 Mar;182(3):257-62.
⁵ Stubbs TM. Oxytocin for labor induction. Clin Obstet Gynecol 2000 Sep;43(3):489-94.
⁶ Wing DA. Labor induction with misoprostol. Am J Obstet Gynecol 1999 Aug;181(2):339-45.
⁷ Kolderup L, McLean L, Grullon K, Safford K, Kilpatrick SJ. Misoprostol is more efficacious for labor induction than prostaglandin E2, but is it associated with more risk? Am J Obstet Gynecol 1999 Jun;180(6 Pt 1):1543-50.
⁸ Kulkarni R, Hawkins K, Boyle AH. Placental abruption following vaginal administration of prostaglandin E2 for induction of labour. West Engl Med J. 1990 Dec;105(4):114-5.
⁹ Leung A, Kwok P, Chang A. Association between prostaglandin E2 and placental abruption. Br J Obstet Gynaecol. 1987 Oct;94(10):1001-2.
¹⁰ Rosenblatt RA, Dobie SA, Hart LG, Schneeweiss R, Gould D, Raine TR, Benedetti TJ, Pirani MJ, Perrin EB. Interspecialty differences in the obstetric care of low-risk women. Am J Public Health. 1997 Mar;87(3):344-51.
¹¹ Gucciardo L, Thoumsin H, Foidart JM. [The effects of labor induction on the progress of childbirth]. Rev Med Liege. 1998 Nov;53(11):665-8.
¹² Goer, Henci. Obstetric Myths versus Research Realities. Westport, CT: Bergin and Garvey, 1995. 254-255.
¹³ Ibid.
¹⁴ Rojansky N, Tanos V, Reubinoff B, Shapira S, Weinstein D. Effect of epidural analgesia on duration and outcome of induced labor. Int Gynaecol Obstet 1997 Mar;56(3):237-44.
¹⁵ Dublin S, Lydon-Rochelle M, Kaplan RC, Watts DH, Critchlow CW. Maternal and neonatal outcomes after induction of labor without an identified indication. Am J Obstet Gynecol 2000 Oct;183(4):986-94.
¹⁶ Brisson-Carroll G, Fraser W, Breart G, Krauss I, Thornton J. The effect of routine early amniotomy on spontaneous labor: a meta-analysis. Obstet Gynecol 1996 May;87(5 Pt 2):891-6.
¹⁷ Sheiner E, Segal D, Shoham-Vardi I, Ben-Tov J, Katz M, Mazor M. The impact of early amniotomy on mode of delivery and pregnancy outcome. Arch Gynecol Obstet 2000 Sep;264(2):63-7.
¹⁸ Molnar E, Sloboda L. [Induction of labor—personal results]. Med Pregl. 1991;44(7-8):323-5.
¹⁹ Boulvain M, Marcoux S, Bureau M, Fortier M, Fraser W. Risks of induction of labour in uncomplicated term pregnancies. Paediatr Perinat Epidemiol. 2001 Apr;15(2):131-8.
²⁰ Yawn BP, Wollan P, McKeon K, Field CS. Temporal changes in rates and reasons for medical induction of term labor, 1980-1996 Am J Obstet Gynecol 2001 Mar;184(4):611-9. ²¹ Sheehan KH. Caesarean section for dystocia: a comparison of practices in two countries. Lancet 1987;1(8532):548-551.
²² Mintz MC and Landon MB. Sonographic diagnosis of fetal growth disorders. Clin Obstet Gynecol 1989;161(3):646-653.
²³ Levine AB, Lockwood CJ, Brown B, Lapinski R, Berkowitz RL. Sonographic diagnosis of the large for gestational age fetus at term: does it make a difference? Obstet Gynecol. 1992 Jan;79(1):55-8.
²⁴ Chauhan SP, Cowan BD, Magann EF, Bradford TH, Roberts WE, Morrison JC. Intrapartum detection of a macrosomic fetus: clinical versus 8 sonographic models. Aust N Z J Obstet Gynaecol. 1995 Aug;35(3):266-70.
²⁵ Leaphart WL, Meyer MC, Capeless EL. Labor induction with a prenatal diagnosis of fetal macrosomia J Matern Fetal Med 1997 Mar-Apr;6(2):99-102.
²⁶ Combs CA, Singh HB, and Koury JC. Elective induction versus spontaneous labor after sonographic diagnosis of fetal macosomia. Obstet Gynecol 1993:81(4):492-496.
²⁷ Weeks JW, Pitman T, Spinnato JA 2nd. Fetal macrosomia: does antenatal prediction affect delivery route and birth outcome? Am J Obstet Gynecol 1995 Oct;173(4):1215-9.
²⁸ Seaward PG, Hannah ME, Myhr TL, Farine D, Ohlsson A, Wang EE, Hodnett E, Haque K, Weston JA, Ohel G. International multicenter term PROM study: evaluation of predictors of neonatal infection in infants born to patients with premature rupture of membranes at term. Am J Obstet Gynecol. 1998 Sep;179(3 Pt 1):635-9.
²⁹ McCaul JF 4th, Rogers LW, Perry KG Jr, Martin RW, Allbert JR, Morrison JC. Premature rupture of membranes at term with an unfavorable cervix: comparison of expectant management, vaginal prostaglandin, and oxytocin induction. South Med J. 1997 Dec;90(12):1229-33.
³⁰ Shalev E, Peleg D, Eliyahu S, Nahum Z. Comparison of 12- and 72-hour expectant management of premature rupture of membranes in term pregnancies. Obstet Gynecol. 1995 May;85(5 Pt 1):766-8.
³¹ Ottervanger HP, Keirse MJ, Smit W, Holm JP. Controlled comparison of induction versus expectant care for prelabor rupture of the membranes at term. J Perinat Med. 1996;24(3):237-42.
³² Keirse MJ, Ottervanger HP, Smit W. Controversies: prelabor rupture of the membranes at term: the case for expectant management. J Perinat Med. 1996;24(6):563-72. Review.
³³ Magann EF, McNamara MF, Whitworth NS, Chauhan SP, Thorpe RA, Morrison JC. Can we decrease postdatism in women with an unfavorable cervix and a negative fetal fibronectin test result at term by serial membrane sweeping? Am J Obstet Gynecol. 1998 Oct;179(4):890-4.
³⁴ O’Brien JM, Mercer BM, Cleary NT, Sibai BM. Efficacy of outpatient induction with low-dose intravaginal prostaglandin E2: a randomized, double-blind, placebo-controlled trial. Am J Obstet Gynecol. 1995 Dec;173(6):1855-9.
³⁵ Satin AJ and Hankins GD. Induction of labor in the postdate fetus. Clin Obstet Gynecol 1989;32(2):269-277.
³⁶ Devoe LD, Sholl JS. Postdates pregnancy. Assessment of fetal risk and obstetric management. J Reprod Med. 1983 Sep;28(9):576-80.
³⁷ Divon MY, Haglund B, Nisell H, Otterblad PO, Westgren M. Fetal and neonatal mortality in the postterm pregnancy: the impact of gestational age and fetal growth restriction. Am J Obstet Gynecol. 1998 Apr;178(4):726-31.
³⁸ Goer, Henci. Obstetric Myths versus Research Realities. Westport, CT: Bergin and Garvey, 1995. 182-183.
³⁹ Zelop CM, Shipp TD, Cohen A, Repke JT, Lieberman E. Trial of labor after 40 weeks’ gestation in women with prior cesarean. Obstet Gynecol 2001 Mar;97(3):391-3.
⁴⁰ Lydon-Rochelle M, Holt VL, Easterling TR, Martin DP. Risk of uterine rupture during labor among women with a prior cesarean delivery. N Engl J Med 2001; 345(1): 3-8.
⁴¹ Nwachuku V, Sison A, Quashie C, Chau A, Yeh S. Safety of misoprostol as a cervical ripening agent in vaginal birth after cesarean delivery. Obstet Gynecol 2001 Apr;97(4 Suppl 1):S67.
⁴² Blanchette H, Blanchette M, McCabe J, Vincent S. Is vaginal birth after cesarean safe? Experience at a community hospital. Am J Obstet Gynecol 2001 Jun;184(7):1478-84; discussion 1484-7.
⁴³ Sims EJ, Newman RB, Hulsey TC. Vaginal birth after cesarean: to induce or not to induce. Am J Obstet Gynecol 2001 May;184(6):1122-4.
⁴⁴ Baskett TF, Kieser KE. A 10-year population-based study of uterine rupture. Obstet Gynecol 2001 Apr;97(4 Suppl 1):S69.
⁴⁵ Shimonovitz S, Botosneano A, Hochner-Celnikier D. Successful first vaginal birth after cesarean section: a predictor of reduced risk for uterine rupture in subsequent deliveries. Isr Med Assoc J 2000 Jul;2(7):526-8.
⁴⁶ Ravasia DJ, Wood SL, Pollard JK. Uterine rupture during induced trial of labor among women with previous cesarean delivery. Am J Obstet Gynecol 2000 Nov;183(5):1176-9.
⁴⁷ Chayen B, Tejani N, Verma U. Induction of labor with an electric breast pump. J Reprod Med. 1986 Feb;31(2):116-8.
⁴⁸ Dunn PA, Rogers D, Halford K. Transcutaneous electrical nerve stimulation at acupuncture points in the induction of uterine contractions. Obstet Gynecol. 1989 Feb;73(2):286-90.
⁴⁹ Tsuei JJ, Lai Y, Sharma SD. The influence of acupuncture stimulation during pregnancy: the induction and inhibition of labor. Obstet Gynecol. 1977 Oct;50(4):479-8.
⁵⁰ Atad J, Bornstein J, Calderon I, Petrikovsky BM, Sorokin Y, Abramovici H. Nonpharmaceutical ripening of the unfavorable cervix and induction of labor by a novel double balloon device. Obstet Gynecol. 1991 Jan;77(1):146-52.
⁵¹ Manor M, Blickstein I, Ben-Arie A, Weissman A, Hagay Z. Case series of labor induction in twin gestations with an Intrauterine Balloon catheter. Gynecol Obstet Invest. 1999;47(4):244-6.

 

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wp_pharma.doc                                                                         11/17/2001
                                                                                                ©2001 ICAN, Inc.