A few weeks ago "Maria" asked me to take a look at a study she had seen that concluded that elective induction decreased cesarean rates while achieving equally good or better newborn outcomes. This was interesting because we have a bunch of studies on elective induction all concluding the opposite: induction increases the risk of surgical delivery. After reviewing the study, I thought it merited inclusion under "When Research Is Flawed"
(http://www.lamaze.org/Research/WhenResearchisFlawed/tabid/121/Default.aspx). This means, though, that my full analysis and deconstruction will have to wend its way through editing, formatting, and uploading, so while we're waiting, I thought I would give Maria and y'all the nutshell version. For starters, here is the citation and abstract from PubMed:

http://www.ncbi.nlm.nih.gov/sites/entrez?orig_db=PubMed&db=PubMed&cmd=Search&term=%22Annals%20of%20family%20medicine%22%5BJour%5D%20AND%202007%5Bpdat%5D%20AND%20Nicholson%5Bfirst%20author%5D

 Nicholson, J. M., Yeager, D. L., & Macones, G. (2007). 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, 5(4), 310-319.

PURPOSE: Annual cesarean delivery rates in North America are increasing. Despite the morbidity associated with cesarean delivery, a safe preventive strategy to reduce the use of this procedure has not been forthcoming. During the 1990s, clinicians in a rural hospital developed a method of care involving prostaglandin-assisted preventive labor induction. An inverse relationship was noted between yearly hospital rates of labor induction and cesarean delivery. The purpose of our study was to compare cesarean delivery rates between practitioners who often used preventive induction and practitioners who did not, while controlling for patient mix and differences in practice style. METHODS: Between 1993 and 1997, different hospital practitioners used risk-guided prostaglandin-assisted preventive labor induction with differing intensity. We used a retrospective cohort design, based on the practitioner providing prenatal care, to compare birth outcomes in women exposed to this alternative method of care with those in women not exposed. Multiple logistic regression analysis controlled for patient characteristics and clustering by practitioner. RESULTS: The exposed group (n = 794), as compared with the nonexposed group (n = 1,075), had a higher labor induction rate (31.4% vs 20.4%, P <.001), a greater use of prostaglandin E2 (23.3% vs 15.7%, P <.001), and a lower cesarean delivery rate (5.3% vs 11.8%, P <.001). Adjustment for cluster effects, patient characteristics, and the use of epidural analgesia did not eliminate the significant association between exposure to this preventive method of care and a lower cesarean delivery rate. Rates of other adverse birth outcomes were either unchanged or reduced in the exposed group. CONCLUSIONS: A preventive approach to reducing cesarean deliveries may be possible. This study found that practitioners who often used risk-guided, prostaglandin-assisted labor induction had a lower cesarean delivery rate without increases in rates of other adverse birth outcomes. Randomized controlled trials of this method of care are warranted.

The theory behind "preventive induction," which the investigators take pains to distinguish from plain old "elective induction," is that need for cesarean surgery for “cephalopelvic disproportion” and “uteroplacental insufficiency” increases with pregnancy duration past 37 completed weeks. Practitioners can therefore minimize the cesarean rate by inducing labor according to an individualized risk profile so as to ensure optimal gestational length. The investigators call their protocol "Active Management of Risk in Pregnancy at Term (AMOR-IPAT)." Isn't it special that they managed to work the Spanish word for love into their acronym? My favorite indication for AMOR-IPAT is "impending macrosomia."

You will have to wait for the "Flawed Research" posting to see all the details of my argument, but take it from me, what the investigators have measured is nothing more than differences in practice style and the placebo effect of thinking that preventive induction is efficacious. For example, it turns out that just having a family practice doc for a care provider, regardless of whether the FP is a low or high user of AMOR-IPAT, achieves the same reduction in cesarean rate as being a high user. It also turns out that the VBAC rate among high users is 93% compared with 69% among low users. And, of course, we have a large body of consistent research showing that you can achieve equally low cesarean rates and good outcomes without inducing 31%--or, for that matter, 20%--of your women.

What runs chills down my spine is how much this all sounds like the early studies of Active Management of Labor, right down to the misleading terminology and the cure for a problem that does not, in fact, exist. Stay tuned for complete coverage later and consider yourself forewarned of the next "new thing" in obstetric management.

-- Henci