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 - part two