New Study Reveals Non-Clinical Factors Have Significant Impact on VBAC

29 Jul

Although three out of four women who labor for a VBAC have safe normal births, routine repeat cesareans are still the norm in many countries. In the United States, women with a prior cesarean who want to plan a VBAC are at the mercy of the few providers and hospitals who will “allow” them to labor and reduce their own and their infants’ exposure to the adverse health outcomes associated with a surgical birth.

The number of women who do give birth vaginally after a prior cesarean vary widely among providers, hospitals, states, and countries.  To better understand the non-clinical factors that encourage women to labor after a prior cesarean and which models of care influence physicians and hospitals to support VBACs, researchers from Australia conducted a systematic review of 700,000 births in studies published up to 2008 that included data from several countries.  The review was published in the August 2011 issue of the Journal of Advanced Nursing.

Although studies have shown that clinical factors such as induction of labor, use of labor epidurals, and x-ray pelvimetry can impact VBAC success, the authors of this study focused on non-clinical, system-led interventions such as practice guidelines and physician characteristics that promote VBAC and increase the number of women who do end up having a normal birth.

Researchers found several non-clinical interventions that had a significant impact on increasing VBAC rates.

Provider Guidelines, Policies, and Programs for Cesarean or VBAC

After the publication of the first U.S. National Institutes of Health Consensus Development Conference on VBAC in 1980, the VBAC rate in ten hospitals increased from 11% to 29% and the overall VBAC rate rose from 6% to 16%.  When in 1992 Florida state legislation mandated the distribution of cesarean practice guidelines to all obstetricians the state VBAC rate increased from 22% to 31%. A 1996 study showed that across 55 U.S. hospitals VBAC rates increased from 12.6% to 18.5% when the then current ACOG guidelines were widely distributed. (The ACOG recommendation that emergency services be “immediately available” for all women laboring for a VBAC in hospital was first introduced in 1999 and has led to the most recently reported 8.4% national VBAC rate.)

When a small Canadian community hospital changed its practices following the National Canadian Consensus Conference on Aspects of Cesarean Birth (1985) the number of women who labored for a VBAC increased from 7% to 79%.

Local guidelines developed by individual U.S. hospitals also had an impact. When clinicians were encouraged to take a more conservative approach to cesareans, the number of women who labored for a VBAC increased from 32% to 84% and the number of women who did have a vaginal birth increased from 65% to 84%.

The successful approach to increasing VBAC in two studies (published in 2006 and 2008) had a long-term impact. After six years, despite the fact that the number of women with a prior cesarean doubled (7-14%) the number of women who labored for a VBAC remained high and VBAC births increased from 53% to 70%.  Only one study published in 2001 reported negative results, a 7% decline in VBACs despite hospital and management policies that encouraged physicians to support VBAC. This study reflected the national trend of declining VBACs following the 1999 ACOG guidelines.

Audit and Feedback

The audit and feedback approach establishes regular audits of individual physicians’  cesarean rates and the results are reported back to the physicians with the expectation that the high cesarean rate physicians would change their practice patterns and support VBAC.  Researchers found that in the three studies they reviewed, this approach was not very successful.  However, in one study in which physicians were audited and asked to defend their decisions to perform cesareans, over a 10-year period the cesarean rate decreased and the number of women who labored for a VBAC increased from 35.6% to 54.5%.

Style of Care

Researchers also looked at how VBAC attempts and rates differed with different hospital characteristics (size, tertiary or non-tertiary), physician practice style and women’s insurance status. Two studies showed that VBAC was more likely to occur in university/teaching hospitals but one study showed no difference. One study found that although VBAC rates varied from hospital to hospital, hospitals where women were allowed to labor longer had higher rates of successful VBACs regardless of the number of women who labored after a cesarean.

When looking at hospital characteristics researchers found that women were more likely to have a VBAC in hospitals with intermediate or high obstetric resources including a higher number of beds, births, and obstetricians. Women were also more likely to have a VBAC with a female physician, with an obstetrician rather than with a GP and in hospitals with an overall lower cesarean rate. In contrast, one study reported women under the care of a family physician  (81%) were much more likely to labor for a VBAC than women under the care of an obstetrician (51%) and were more likely to actually have a vaginal birth (76% vs. 64%).  In one study published in 1998, women were more likely to try for a VBAC (76%) when their obstetrician’s cesarean rate was below 15% compared to those whose overall rate was greater than 15% (45%).  Women cared for by the low cesarean rate physicians were also more likely to end up with a VBAC (83% vs. 66%).

With regard to insurance status, researchers found inconclusive results. When comparing women with private health insurance with women covered by the public health system, two studies found no difference between the groups. One reported that privately insured women were less likely to attempt a VBAC (50% vs. 64%), another showed a significantly lower VBAC rate in privately insured women (8.1%) than in women insured by the public health system (25%) and one reported a seven times higher repeat cesarean rate for women who were privately insured.

Information Provided To Expectant Mothers

Does providing information about elective repeat cesarean and VBAC during the prenatal period make a difference on women’s choice of birth after a prior cesarean? In a Canadian study of 11 hospitals where women were randomized to either receive an educational pamphlet or to have an individual discussion with a professional, slightly more women (53%) chose to labor for a VBAC after a discussion than after having received a pamphlet (49%).  A U.K. study looked at the effects of   two computer-based decision aids on decisional conflicts compared to usual care. Women who received usual care were somewhat less likely to have a VBAC  (30%) than women who were given the computer-based decision aids ((37%).  In one study a significantly higher number of women ((63%) who participated in a prenatal educational counseling program on choice of birth after a cesarean chose to labor compared with only 38% in the control group.

Overall Conclusions

The researchers who  reviewed these studies that covered a span of 20 years concluded that non-clinical factors do have a significant impact on women’s choice for VBAC and the number of women who subsequently do have a vaginal birth. The most significant difference seems to be local “ownership of the desire to reduce CS rates or increase VBAC rates.”  Also, individual physician characteristics may impact the number of women whose choose to labor for a VBAC and have a normal birth. The study also concluded that involving women more fully in decision-making and providing evidence-based information about their options should be incorporated into the care of all women with a previous cesarean section.

One Response to “New Study Reveals Non-Clinical Factors Have Significant Impact on VBAC”

  1. hélène vadeboncoeur August 8, 2011 at 6:55 am #

    Interesting, this systematic literature review on the factors that have a significant impact on VBAC. I want to comment on the Canadian study, in the site section Information provided to expectant mothers, where women were randomized at either receiving an educational pamphlet or have a discussion with a professional : first, the ‘intervention’ was not strong enough to produce any significant result (2 hours total : one hour with a research nurse – not a clinician -, and one hour with a woman who had had a VBAC. Although the idea of informing women about VBAC with more personal means than a pamphlet is interesting, women need more than that to overcome all the barriers the society and medical system has put in place to discourage them from wanting a VBAC or to scare them.

    Vadeboncoeur is the author of Birthing Normally After a Cesarean or Two (Fresh Heart Publishing).

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