Mamas on Bedrest: Why “NOT” Induce? Part I

January 28th, 2011

The next 2 blog posts will contain excellent information compiled by Chidlbirth Connection on labor induction. I am presenting the information here, as it is on their website because it is the most comprehensive information that I have seen. I could not do a more thorough review nor add anything pertinent to what has been written. For more information on Childbirth Connection, visit their website.

What is the bottom line about induction of labor?

Unfortunately, research provides very few simple answers about induction of labor. For many of the reasons women undergo induced labor, we simply lack the research to say for sure whether the benefits outweigh the harms. For other common reasons for induction, research actually suggests that waiting for labor is safer.

The safety and effectiveness of labor induction depends on the health of the woman and her baby, whether the woman has given birth before, the timing of the induction, the method used, the characteristics of the birth facility, and many other factors. When studies combine many women with different circumstances – as most studies and all systematic reviews do – it becomes impossible to say for sure what the risks and benefits of induction for an individual woman might be.

Despite these limitations, studies provide some consistent findings. These findings come from studies of elective induction of labor – that is, induction without a medical reason (King and colleagues 2010, a systematic review). Looking at the outcomes of elective induction lets us evaluate the outcomes of induction itself, rather than the outcomes of complications that led to the induction.

  • Elective induction before 41 weeks increases the chance of having a c-section if the cervix is “unripe,” especially in first-time mothers.
  • Using medications or procedures to “ripen” the cervix does not decrease the chance of a c-section.
  • Women in induced labor are more likely to request an epidural for pain relief than women in spontaneous labor. Epidurals introduce their own set of risks, including increased chance of instrumental vaginal delivery and fever in labor, which is often treated with antibiotics and may result in unnecessary tests and treatments for the baby and separation of the mother and baby after birth. (These and other risks are discussed in greater detail in our Labor Pain section.)

Induction methods also have a predictable effect on the type of care and monitoring you will need in labor. Induction of labor nearly always involves having at least one intravenous (IV) line, continuous electronic fetal monitoring, and medications after birth to reduce the risk of hemorrhage (excessive bleeding). The IV and fetal monitoring lines make it harder to move around in labor, which can increase pain. Many hospitals have policies that restrict what women can eat and drink when undergoing induction of labor.

In recent years, evidence has been mounting that elective delivery before 39 completed weeks clearly increases risks for babies. For optimal outcomes, women may also wish to avoid elective delivery at 40 or 41 weeks and to make informed decisions about this practice after 41 weeks.

In what circumstances does induction of labor improve health outcomes for the mother, baby, or both?

Although decisions about whether and when to induce labor must be individualized, a 2009 systematic review of the research on induction of labor (Mozurkewich and colleagues 2009) found only two conditions for which induction of labor seems to reliably improve health outcomes, and a later study identified a third (Koopmans and colleagues 2009). In all three cases, differences in important health outcomes were small and the studies left some important questions unanswered.

  • Pregnancy lasting beyond 41 weeks: Various studies have compared induction of labor at or after 41 weeks with expectant management, which involved repeated tests of fetal well-being between 41 and 42 weeks. Taken together, the studies suggest that for every 369 women induced during the week between 41 and 42 weeks, one stillbirth or neonatal death may be prevented. The risk of meconium aspiration syndrome (a serious illness that causes respiratory distress) may also be reduced, although studies have come to different conclusions on this outcome. The risk of c-section does not seem to be increased with induction between 41 and 42 weeks, and some studies have shown a decrease.
  • Prelabor rupture of membranes (PROM) at term (37-42 weeks): A large randomized controlled trial compared immediate induction with waiting up to three days for labor and only inducing before then if a complication developed. The study found that inducing right away was associated with a lower chance that the mother would develop an infection or the baby would go to the neonatal intensive care unit. Immediate induction did not affect the likelihood of c-section, newborn infection, or other important outcomes. These results suggest that early induction is the best approach. Several systematic reviews that relied on data from this large RCT came to the same conclusion. However, most women in the trial had vaginal exams before labor began, and those who carried Group B Strep (GBS, a bacteria that may be present in a woman’s vagina and raises the risk of infection for the baby) were not given antibiotics to prevent infection. Many caregivers and researchers believe that many infections reported in the trial might have been prevented by awaiting labor before performing a vaginal exam and providing antibiotics to women with GBS. These are standard practice in U.S. maternity care settings today.
  • Increased blood pressure near the end of pregnancy: High blood pressure that develops in pregnancy may occur without other symptoms or signs (known as gestational hypertension) or with protein in the urine (a more dangerous condition known as preeclampsia). High blood pressure can affect the flow of oxygen to the baby, increase the chance of complications during labor, and is a risk factor for rare but very serious outcomes like stroke and seizures.Researchers studied outcomes of women at or beyond 36 weeks of pregnancy who developed gestational hypertension (diastolic blood pressure – generally, the second number in a blood pressure reading – between 95 and 110) or mild preeclampsia (diastolic blood pressure between 90 and 110 and protein in the urine). The study found that inducing labor right away improved maternal outcomes. However, they defined “poor maternal outcome” to include any cases where women developed severe high blood pressure. Very few of these women experienced serious health problems as a result of the blood pressure increase. There were no significant differences in the number of serious problems like seizure, need for intensive care, or postpartum hemorrhage, although the study was too small to show whether there were differences in these uncommon outcomes. There were also no significant differences in newborn outcomes, although a later study showed that neonatal intensive care admission, need for artificial ventilation (a machine to help the baby breathe), low birth-weight, and jaundice were more common the earlier a woman with mild gestational hypertension was induced, with best outcomes in the group induced after 38 weeks (Koopmans and colleagues 2009; Barton and colleagues 2011).In the randomized controlled trial, women with mild preeclampsia (versus gestational hypertension), women having their first baby, and those with the least amount of cervical dilation were the most likely to benefit from a policy of early induction. This is most likely because preeclampsia is a more serious condition than gestational hypertension and first-time mothers and those who haven’t begun dilating would have remained pregnant longer, providing more opportunity for their condition to worsen.

What common “reasons” for induction are not supported by rigorous research?

For a surprising number of conditions, the effectiveness of induction has not been proven (Mozurkewich and colleagues 2009, a systematic review). Yet many women have induced labor with the understanding that they or their babies will benefit. More or larger studies are needed to confirm the benefits and harms of induction in these situations. These include:

  • Preterm prelabor rupture of the membranes (PPROM): A systematic review of 4 randomized controlled trials involving a total of 389 women with ruptured membranes between 30 and 36 weeks found no difference in important health outcomes between those who were induced right away and those who awaited labor. A new, larger study is currently underway.
  • Twin pregnancy: A single, small randomized controlled trial compared routine induction at 37 weeks with expectant management and found no differences in important health outcomes. More research is needed.
  • Gestational diabetes requiring insulin: One randomized controlled trial looked at the outcomes of 200 women randomized to be induced at 38 weeks or await labor. Those who awaited labor were more likely to have large babies. There were no differences in health outcomes for the mothers or babies, however. The trial may have been too small to detect these differences.
  • Intrauterine growth restriction (IUGR) at term: Two trials involving a combined 683 women found no benefit or harm to induction of labor for suspected IUGR at term. More and larger trials are needed.
  • Oligohydramnios (too little amniotic fluid): A single, small randomized controlled trial compared induction of labor with expectant management (watching fetal wellbeing closely until 42 weeks) for women with oligohydramnios at 41 weeks. The women were healthy and did not have other risk factors or complications. The study found no difference in maternal or newborn outcomes, but was too small to detect some important differences that may exist. No trials of induction for isolated oligohydramnios at other gestational ages were found.

For other conditions, the available evidence suggests induction is ineffective, harmful, or both (Mozurkewich and colleagues 2009, a systematic review). Despite the research, many caregivers continue to recommend induction of labor for these reasons. These reasons include:

  • Suspected macrosomia (too big baby): According to a systematic review of several studies involving over 3700 women, inducing labor when the caregiver believes the baby is large does not improve neonatal outcomes and appears to increase the chance that the woman will have a c-section.
  • Intrauterine growth restriction before term: A large, multi-center randomized controlled trial of over 1000 women with growth-restricted fetuses between 24 and 36 weeks and abnormal Doppler artery blood flow studies showed that induction increased the likelihood of c-section. In addition, babies born before 31 weeks in the induction group were more likely to have severe disabilities at 2 years of age than babies born before 31 weeks in the await labor group.


References

Barton JR, Barton LA, Istwan NB, et al. Elective delivery at 34(0/7) to 36(6/7) weeks’ gestation and its impact on neonatal outcomes in women with stable mild gestational hypertension. Am J Obstet Gynecol. 2011;204(1):44.e1-44.e5..

Boers KE, Vijgen SM, Bijlenga D, et al. Induction versus expectant monitoring for intrauterine growth restriction at term: Randomised equivalence trial (DIGITAT). BMJ. 2010;341:c7087

Koopmans CM, Bijlenga D, Groen H, et al. Induction of labour versus expectant monitoring for gestational hypertension or mild pre-eclampsia after 36 weeks’ gestation (HYPITAT): A multicentre, open-label randomised controlled trial. Lancet. 2009;374(9694):979-988.

Mozurkewich E, Chilimigras J, Koepke E, Keeton K, King VJ. Indications for induction of labour: A best-evidence review. BJOG. 2009;116(5):626-636.

 
King V, Pilliod R, Little A. Rapid review: Elective induction of labor. Portland: Center for Evidence-based Policy; 2010 Accessed January 5, 2011 at http://www.ohsu.edu/xd/research/centers-institutes/evidence-based-policy-center/med/index.cfm.

 

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