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Abstract

  1. Top of page
  2. Abstract
  3. Cause-and-Effect issues
  4. More than a scoring system
  5. Not a simple solution
  6. The randomized controlled trial
  7. References

ABSTRACT: “Preventive Labor Induction-AMOR-IPAT” is a method designed to time induction before the fetus becomes too large or the placenta dysfunctional. In two retrospective cohort studies and one randomized trial, the developers claim to have reduced cesarean section rates and improved newborn outcomes. These claims have yet to be substantiated in an adequately powered trial, but having decided on the need for an induction, the investigators do manage inductions in a woman-centered and intimate style that has merit. (BIRTH 36:1 March 2009)

A new approach to preventing or managing the plague of elevated worldwide cesarean section rates has caused much excitement in the recent literature, in clinical circles, and in the lay press. The approach, known as “Preventive Labor Induction-AMOR-IPAT,” was developed by James Nicholson, a family physician from Pennsylvania, who has been studying the method in a variety of settings in a series of cohort studies (1,2) and most recently in a small randomized controlled trial (3).

In essence, the investigators have created a tool to assess the likelihood that a particular pregnant woman will run into difficulty that will result in a cesarean section or a placenta/fetus that cannot withstand the stress of labor. Using the AMOR-IPAT scoring system, an ideal delivery date is computed for each woman. In practice, most women are induced at around 38 weeks’ gestation. Applied properly, the method requires maternity care practitioners to remain intimately and personally engaged with the laboring woman.

Cause-and-Effect issues

  1. Top of page
  2. Abstract
  3. Cause-and-Effect issues
  4. More than a scoring system
  5. Not a simple solution
  6. The randomized controlled trial
  7. References

Given the many studies that have shown that early induction causes a rise in cesarean sections and increased risk to the fetus through prematurity and other problems, the AMOR-IPAT method appears counterintuitive. In addition, the rather astonishing reductions in cesarean section rates reported in the cohort studies (1,2) (4% vs 16.7% in one cohort study and 5.3% vs 11.8% in another) were surprising. What is in dispute is whether the method was responsible for the cesarean reductions, or some other concurrent reason. A more detailed assessment of the study methods has been made elsewhere (4,5).

More than a scoring system

  1. Top of page
  2. Abstract
  3. Cause-and-Effect issues
  4. More than a scoring system
  5. Not a simple solution
  6. The randomized controlled trial
  7. References

It is most important to understand the functioning of the physician group applying the study approach. According to Dr. Wendy Barr (personal communication, November 17, 2008), who has extensive clinical experience with the AMOR-IPAT method, central to its success is what she calls the “Art of Induction,” that is, how the inductions are conducted. She elaborates:

The classic model for induction is based on a goal of a delivery within 24 hours. This means that labor is often rushed and intravenous Pitocin and artificial rupture of the membranes (AROM) are used early. In AMOR-IPAT, the goal of the induction is achieving a vaginal birth (with a healthy mom and baby), and time is not a factor. The induction uses a woman-centered approach that pays attention to circadian rhythms and quality-of-life factors such as eating, ambulation, and hygiene. A typical induction for a nulliparous woman with an unfavorable cervix would start at 7 pm after she has had dinner. She then comes to the hospital and cervical ripening with Cervidil would be given. If the woman requires medication for pain or sleep, that would also be provided, so that she rests through the night. In the morning, the Cervidil is removed at 7 am and the woman can eat breakfast, shower, and move around. Once she is comfortable, intravenous Pitocin is started for the next 8 hours or so. This usually results in about 50 percent of women entering active labor. They continue on Pitocin stimulation, receive AROM at cervical dilation of about 4 cm and epidural analgesia as requested. Birth occurs often within 24 hours. For the other half of women not yet in active labor (usually nulliparous women with an unfavorable cervix), the Pitocin is stopped in the evening, the woman is offered dinner, shower/bath, and ambulation—and either another dose of Cervidil or misoprostol is given. By the next morning, if the cervix is still unfavorable after breakfast, a shower/bath and ambulation are offered, a Foley balloon is placed, and Pitocin started (epidural being offered before the Foley balloon if desired). Once the cervix is 4 cm and the woman is having regular contractions on Pitocin and the station is - 2, AROM is performed--and usually delivery is achieved that day.

Women tolerate this method well because their needs are met (eating, sleeping, and bathing), and the timing is in line with their normal rhythms until active labor is achieved. The provider remains patient, and is often working in teams, which removes the influence of extreme sleep deprivation from the decision-making process and does not tie a single provider to the labor floor for 3 days (which would encourage a quick delivery but may influence a provider to jump to a cesarean). The unfortunate caveat to AMOR-IPAT is that some providers may only take away the timing of induction, while missing the full induction method and underlying birth philosophy.

The “Art of Induction,” as described by Dr. Barr, is missing from the publications on the method and explains much of the success of the AMOR-IPAT technique. Clinicians will recognize in her detailed description, inherent flexibility and a caring approach and respect for the woman’s dignity, as well as the recognition that for any labor to be successful, induced or not, attention to food, rest, and preserving the woman’s dignity must be appreciated. This background is needed for any analysis of the reported studies of the AMOR-IPAT method to be understood.

Not a simple solution

  1. Top of page
  2. Abstract
  3. Cause-and-Effect issues
  4. More than a scoring system
  5. Not a simple solution
  6. The randomized controlled trial
  7. References

Initial reading of the AMOR-IPAT method of preventive labor induction indeed makes it appear as if the scoring system and timing of the induction tells the tale. This interpretation seems too simple to be accepted, which is why Dr. Barr’s expansion is so helpful. Nicholson and the AMOR-IPAT study physicians have a practice style very different from the usual care group. They are a dedicated group with a coherent philosophy who practice an intimate and engaged style of care that is not representative of usual care. This approach allows them to use the method and obtain good maternal results. The AMOR-IPAT group maintains a substantially lower epidural analgesia rate than the usual care group (and they use their epidurals during the active phase of labor). This is one feature of their intimate and engaged style (6) that avoids many malpositions (7), and they spend more time with their patients.

Based on the cohort studies (1,2), the developers of AMOR-IPAT method do not convince that their intervention was the reason for the outcomes favoring their approach. Many confounders, demographic imbalances, and biases were at play, the most important being the Hawthorne or experimental effect caused by the enthusiasm of the developers of the method. This factor raised concern that if the approach were to be taken up by physicians less committed to intimate and personalized care than the investigators and their disciples, our already industrialized maternity care patterns would be augmented by yet another reason to consider birth as a pathological event in waiting.

The randomized controlled trial

  1. Top of page
  2. Abstract
  3. Cause-and-Effect issues
  4. More than a scoring system
  5. Not a simple solution
  6. The randomized controlled trial
  7. References

To their credit, the AMOR-IPAT investigators have conducted a randomized trial (3), which was necessary to eliminate study biases. It involved only study physicians who were not part of the group developing the approach, so that one could appreciate what might happen if the method were to come into general usage. In this trial, the investigators have overcome many issues and concerns inherent in their previous retrospective cohort studies. Cesarean section was still the primary outcome, but in this unblinded trial, no statistical difference was found between the experimental and the control arms. Moreover, the cesarean section rate in both arms was exceedingly low (10.3% vs 14.9%), leading to questions of generalizability.

Having found no statistical difference in their primary outcome, the authors went on to describe a very large number of secondary outcomes, claiming that the experimental group had a lower neonatal intensive care unit admission rate, a higher uncomplicated vaginal birth rate, and lower mean adverse outcomes index score, compared with the usual care group. These created compound scores were not reflected in any accepted measures of newborn illness. Thus there was no difference in thick meconium, late decelerations, bradycardia, tachycardia, respiratory disorders, or low Apgar scores, and only one baby reached the more intensive special care baby unit. So what were the newborns admitted for? Likely, conditions of a transitional nature that are always subject to judgment calls. Moreover, differences in the two composite measures were driven by the neonatal intensive care unit outcomes. In addition, one of the composite measures, the constructed “uncomplicated vaginal birth,” is an ad hoc measure, whereas the other, while previously reported, is unvalidated.

Since Nicholson et al (3) claim to have been underpowered for the primary outcome, they now plan a larger randomized trial. Until they conduct one, it would be wise to reserve judgment on this method and refrain from promoting its application under the conditions of usual practice, where results are likely to be considerably less desirable than those in the hands of this dedicated group, who care for their patients with an induction approach and style to be emulated, even without application of the scoring method of “AMOR-IPAT.”

References

  1. Top of page
  2. Abstract
  3. Cause-and-Effect issues
  4. More than a scoring system
  5. Not a simple solution
  6. The randomized controlled trial
  7. References
  • 1
    Nicholson JM, Kellar LC, Cronholm PF, Macones GA. Active management of risk in pregnancy at term in an urban population: An association between a higher induction of labor rate and a lower cesarean delivery rate [see comment]. Am J Obstet Gynecol 2004;191(5):15161528.
  • 2
    Nicholson JM, Yeager DL, Macones G. A preventive approach to obstetric care in a rural hospital: Association between higher rates of preventive labor induction and lower rates of cesarean delivery. Ann Fam Med 2007;5(4):310319.
  • 3
    Nicholson JM, Parry S, Caughey AB, et al. The impact of the active management of risk in pregnancy at term on birth outcomes: A randomized clinical trial. Am J Obstet Gynecol 2008;198(5):511.e1511.e15.
  • 4
    Klein MC. Association not causation: What is the intervention? Ann Fam Med 2007;5(4):294297.
  • 5
    Klein MC, Kaczorowski J, Brant R. “Preventive induction” fails to demonstrate benefits for mothers or newborn infants. Am J Obstet Gynecol (In press).
  • 6
    Klein MC, Grzybowski S, Harris S, et al. Epidural analgesia use as a marker for physician approach to birth: Implications for maternal and newborn outcomes. Birth 2001;28(4):243248.
  • 7
    Yancey MK, Zhang J, Schweitzer DL, et al. Epidural analgesia and fetal head malposition at vaginal delivery. Obstet Gynecol 2001;97(4):608612.