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Electronic letters published:
![[Read Comment]](/icons/misc/sectionDOWN.gif){kind=icon}
Re: Impact of ACOG Guidelines on VBAC is Underestimated
Impact of ACOG Guidelines on VBAC is Underestimated
Re: Could pregnancy complications confound the relationship between route of delivery and outcomes?
Could pregnancy complications confound the relationship between route of delivery and outcomes?
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Susan Hughes, Fresno, CA, USA Research Director, UCSF Fresno Family and Community Medicine, John Zweifler
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Dr. Karel correctly identifies one of the limitations of using birth certificate data; unplanned VBAC deliveries are indistinguishable from planned VBAC deliveries. In our study this would underestimate the impact of the ACOG guideline revisions because unplanned deliveries would presumably remain similar over both time periods while considerably fewer planned VBAC deliveries occurred after the guideline changes. The fact that Black women have a higher rate of pre-term delivery could be a contributing factor to why our study found the decline of attempted VBAC delivery for Black women was 34% compared to a 45% decline for White women. The strength of our study was seven years of birth data from the state of California. Our evidence showed that newborn mortality was similar, regardless of delivery method, for normal and large birth-weight infants. Many factors contribute to the patient/provider decision between attempting a VBAC delivery and scheduling a repeat cesarean. Certainly the medico-legal risks and complexities of the consent process contribute to a provider’s willingness to counsel a patient to attempt a VBAC. How race and ethnicity factor into considerations regarding a VBAC delivery after previous cesarean is an area that still needs to be explored in a prospective manner and will require more variables than are available from a birth certificate. Zweifler J, Garza A, Hughes S, Stanich MA, Hierholzer A, Lau M. Ann Fam Med; 2006 May-Jun;4(3): 228-234. Competing interests: None declared |
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Daphne J. Karel, Greenwood, USA MD, Associate Faculty Family Medicine
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Zweifler et al in Vaginal Birth after Cesarean in California: Before and After a Change in Guidelines explored the impact of the 1999 ACOG guideline revision on vaginal birth after cesarean (VBAC) rates.(1,2) The authors attempt to measure the impact of the guideline revisions on the rate of VBAC in different populations by region, ethnicity, and education. If we want to demonstrate the true impact of these guidelines, other variables must be studied. The authors reported attempted VBAC rate and percent decline for the Black, Hispanic, and Asian populations, but these numbers do not accurately reflect the impact of the guidelines. Because of the data collection method, unintentional VBACs were included in the attempted VBAC numbers. Lack of obstetric care, precipitous delivery, and preterm delivery are all classified as VBAC by this method. Physicians have less control over unplanned VBACs, therefore the measured rate of change has been underestimated. This effect is more pronounced in populations that have a higher rate of unintentional delivery. For example, African-Americans have a higher rate of preterm labor.(3) Inadequate education, health care access barriers, and socioeconomic problems that contribute to preterm labor and out-of-hospital delivery are higher in some ethnicities and regions.(3,4) Barriers to adequate health care in minority groups are most pronounced in controversial interventions such as whether to schedule a repeat C-section or plan a VBAC. In our community, many obstetricians are unwilling to accept the medico-legal risk and increased time commitment of attempted VBAC in pregnancies where they are unlikely to get paid. Language barriers make the extensive consent for VBAC difficult. Migrants with C-section histories often have difficulty obtaining operative reports required for VBAC. Hispanic women in our community choose to stay with a more culturally friendly practice that no longer provides VBACs instead of transferring to an office providing both options. Restrictive ACOG VBAC guidelines combined with cultural and economic barriers complicate an already difficult issue. In a medical situation where there are two viable options, is there a loss of choice in some groups? Addressing this issue is vital to developing a culturally responsible community with equitable medical care. 1. Zweifler J. et al. Vaginal Birth after Cesarean in California: Before and After a Change in Guidelines. Ann Fam Med. May/June 2006. Vol 4(3):228-234. 2. ACOG Practice Bulletin #54: vaginal birth after previous cesarean. Obstet Gynecol. 2004.Vol 104:203-212. 3. Newton, Edward R. Preterm Labor, Preterm Premature Rupture of Membranes, and Chorioamnionitis. Clinics in Perinatology. Sept 2005. Vol 32(3):571-600 4. Institute of Medicine report on racial and ethnic disparities: Unequal Treatment; Confronting Racial and Ethnic Disparities in Health Care (national Academies Press, 2002) Competing interests: None declared |
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John A Zweifler, Fresno, Ca. Chief, UCSF Fresno Family and Community Medicine Dept.
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Dr. Viswanathan points out the importance of accounting for pregnancy complications when evaluating studies of delivery outcomes. In fact, as we reported in our study, in a regression analysis including only newborns of normal and large birth weight, pregnancy complication was the only significant predictor of neonatal mortality.(1). However, suggesting that the major finding of our study was that the risk of neonatal mortality is higher with attempted vaginal birth after cesarean (VBAC) than with repeat cesarean birth is a misrepresentation. Our two major findings, as stated in the conclusion of our abstract, were: neonatal and maternal mortality rates did not improve despite increasing rates of repeat cesarean delivery during the years after the American College of Obstetricians and Gynecologists (ACOG) 1999 VBAC revision, and women with infants weighing 1500 gms or more encountered similar neonatal and maternal mortality rates with VBAC or repeat cesarean delivery. The authors believe our study significantly contributes to the evidence base by identifying that excess neonatal mortality when attempting a VBAC is isolated to the less than 1500 gm birth weight category. In our article, we propose plausible explanations for this observation. Although our study was limited to neonatal mortality due to the constraints of birth certificate information, our data suggests studies that found higher rates of neonatal complications should be reviewed to see if complications are also concentrated in very low birth weight infants. Ultimately we agree with Dr. Viswanathan that women considering VBAC should be provided with a balance presentation based on evolving evidence, including the encouraging findings regarding VBAC outcomes found in our study. (1)Zweifler J, Garza A, Hughes S, Stanich MA, Hierholzer A, Lau M. Annals of Family Medicine; 2006;4(3): 228-234. Competing interests: None declared |
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Meera Viswanathan, Durham, USA Health Services Research Analyst, RTI International
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In their study of neonatal mortality, Zweifler et al. suggest that the risk of neonatal mortality is higher with attempted vaginal birth after cesarean (VBAC) than with repeat cesarean birth.(1) Their analysis covers a period (1996-2002) that includes changes in the American College of Obstetricians and Gynecologists (ACOG) guidelines to discourage VBAC in situations in which women lack access to emergency physicians. Their study also shows that the risk of neonatal deaths was higher in the period following the ACOG guideline revision, during which VBAC rates plummeted. How are readers to assess evidence of an increased risk of neonatal mortality with attempted VBAC against evidence of an increased risk of neonatal mortality after the implementation of policies restricting VBAC? The authors do not directly provide answers to this conundrum, but some clues emerge from their other findings. The authors note that "recorded pregnancy complication rates were higher in women who attempted VBAC than those who had a repeat cesarean section." In addition, they report that the percentage of decrease in attempted VBAC between the two periods was less in “those with pregnancy complications." Together, these findings suggest that healthier women were less likely to have attempted VBAC after the revision of ACOG guidelines than before the revision. Could the decline in the relative proportion of healthier women with attempted VBAC from 1996 to 2002 explain the rise in risk of neonatal mortality following the ACOG revision? Could this factor account as well for the rise in the risk of neonatal mortality following a VBAC? Our systematic review of cesarean delivery on maternal request examined a wide range of outcomes, including maternal and neonatal mortality, following planned cesarean delivery and planned vaginal delivery.(2) Our analysis suggests that the underlying health status of the women in studies comparing vaginal delivery to cesarean delivery could confound the relationship between route of delivery and outcomes. With current coding systems, many retrospective studies cannot distinguish adequately between planned and unplanned routes of delivery, nor can they account for medical indications that shape the decision on planned route of delivery. Nevertheless, policies continue to be based on evidence from such studies, with unintended, and possibly disastrous, consequences for women as they weigh the choice between planned vaginal delivery and planned cesarean delivery, whether for the primary birth or for subsequent births. As researchers, we have a collective responsibility to improve the quality of that evidence through prospective comparisons of outcomes that account clearly for underlying health conditions and planned route of delivery. (1)Zweifler J, Garza A, Hughes S, Stanich MA, Hierholzers A, Lau M. Annals of Family Medicine; 2006;4(3): 228-234. (2)Viswanathan M, Visco AG, Hartmann K, Wechter, ME, Gartlehner G, Wu JM, Palmieri R, Funk MJ, Lux, LJ, Swinson T, Lohr KN. Cesarean Delivery on Maternal Request. Evidence Report/Technology Assessment No. 133. AHRQ Publication No. 06-E009. Rockville, MD: Agency for Healthcare Research and Quality. March 2006. Competing interests: None declared |
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