CMSC Midwifery Database in Ontario

VBAC Risks and Benefits:
A Review of the Evidence
American College of Nurse Midwifery 2005
Washington, D.C.
“Hot Topics”
Betty-Anne Daviss, MA, RM
Adjunct Professor, Pauline Jewett Institute of Women’s Studies, Carleton
Kenneth C. Johnson, PhD
Centre for Chronic Disease Prevention and Control
Public Health Agency of Canada
Overview of NACC Study
NACC study example of a trend in the use of
single studies to drive practice
Implications for the way “science” is used
Repercussions for American women on choice
Repercussions internationally on women’s choice
Disturbing Trends
Single studies given more merit than warranted, often
ignoring systematic reviews
1. Hannah, The Term Breech Trial (2000)
2. Pang et al. Washington Home Birth Study (2002)
3. Lydon Rochelle et al., NEJM VBAC study (2001)
4. Lieberman et. al, NACC VBAC Study(2004)
Similarities in the Response to
The Single Studies
1. Studies adopted to practice in isolation of former
2. Adoption of intervention occurred largely because
of editorials and high profile granted to the studies,
regardless of merit.
3. Adoption almost immediate, prompted by hospital
meetings, obstetric association directives, and mass
Similarities in the Response to
These Single Studies
4. Evidence of flaws in the studies or
unwarranted conclusions were not published for
several months, by which time practice was
already changed, and reversal of the decision not
5. Lack of inter-disciplinary or consumer/
professional forums to discuss larger implications
of change of practice.
6. Adoption of each study increased intervention.
Meta-analyses Recommendations
Rosen, Dickinson and Westhoff.
Vaginal Birth after cesarean: a meta-analysis of morbidity
and mortality. Obstet Gynecol. March 1991
Roberts et al.
Trial of Labor or Repeated Cesarean Section Arch Fam Med
Mar/Apr 1997
Mozurkewich and Hutton.
Elective Repeat Cesarean Delivery vs. Trial of Labor:A
meta-analysis of the literature from 1989 to 1999 Am J
Obstet Gynecol Nov 2000
Meta-analyses Recommendations
1. Rosen, Dickinson and Westhoff:
VBAC appears to be a safe component of obstetric
care, and failed VBAC with consequent cesarean
poses no major risks.
Need to modify Cragin’s original dictum to “Once
a cesarean, a trial of labour should precede a
second cesarean except in the most unusual
Meta-analyses Recommendations
2. Roberts R, Bell H, Wall E, Moy J, Hess G, Bower H
In balancing the potentially competing values of
patient preferences vs cost containment, we
concluded that clinicians should counsel women
about the risks, benefits, and costs of TOL and
ERCS, and a guideline should recommend TOL,
but respect a woman’s preference for ERCS.
Meta-analyses Recommendations
3. Mozurkewich and Hutton.
Small increases in the uterine rupture rate and in fetal and
neonatal mortality rates may result from a trial of labor
compared to elective repeat cesarean section.
These increases may be counterbalanced by reductions in
maternal morbidity with a trial of labor, including febrile
morbidity, transfusion, and hysterectomy.
Either a trial of labor or elective repeat cesarean delivery
may be a reasonable option for women with at least one
previous cesarean delivery.
Single study adopted
Lydon-Rochelle et al.
Risk of uterine rupture during labor among
women with a prior cesarean delivery NEJM
Risk of Uterine Rupture During
Labor among VBACs (Lydon-Rochelle)
For women with one prior cesarean
delivery, the risk of uterine rupture is higher
among those whose labor is induced than
among those with repeated cesarean
delivery without labour. Labour induced
with a prostaglandin confers the highest
How the Study Was Used
NEJM Editorial extrapolated
recommendations not contained in the study
 Rather than commentary being we shouldn’t
do induction with VBACs, we shouldn’t do
 ACOG made use of the study at a press
conference to announce to the media the
increased dangers of VBAC
Repercussions of the LydonRochelle Study
All former meta-analyses ignored
 Changed practice within a couple of months
 Response in letters to the editor of the
NEJM and the BMJ not published for six
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% VBAC Low Risk* Mothers, U.S., 1990-2001
* Full-gestation(37+ weeks), vertex presentation, singleton births
Current Changes:
National Cesarean Rates
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
VBAC deliveries - USA 1989-2003
National Study of Vaginal Birth After
Cesarean in Birth Centers (NACC Study)
Prospective study of 1453 attempted
VBACs in 41 U.S. Birth Centers – 19902000
 24% transfer to hospital
 87% VBAC success
NACC Study Uterine Rupture
Perinatal Deaths Uterine Rupture
1 Previous
2 Previous
3 in 1271
3 in 99
NACC Study Perinatal Death
1 Previous
2 Previous
>or= 42 wks.
Fetal &
Neonatal Death
3 in 1271
Fetal &
Neonatal Death
3 in 99
1 in 46
NACC Study Conclusions
“Despite a high rate of vaginal births and few uterine
ruptures among women attempting VBACs in birth
centers, a caesarean-scarred uterus was associated with
increases in complications that require hospital
Therefore, birth centers should refer women who have
undergone previous cesarean deliveries to hospitals for
delivery. Hospitals should increase access to inhospital care provided by midwife/obstetrician teams
during VBACs.”
Using the same logic:
Because women of lower socio-economic
status have higher risk of perinatal death,
they should all go to the best tertiary care
Using Similar Logic:
Landon MB et al. found:
7 maternal deaths in 15, 801 elective cesareans
3 maternal deaths in 17, 898 attempted VBACs
We could therefore conclude that elective caesarean
section should not be done in academic institutions
Alternative Conclusions
Because in this study there was a high rate of
vaginal births and few uterine ruptures
among women attempting VBACs in birth
And because the perinatal mortality of 2 per
thousand in those with a single former
caesarean section is very low (consider the
overall perinatal mortality in the USA)
Alternative Conclusions
therefore, reflection for those planning VBACS in out of
hospital births should be more cautious if they have had
two former caesarean sections or are >=42 weeks.
Women should also be told about the risk of cesareans along
with the risks of VBACs and ruptures (Cesarean risks
include increased odds of infertility, miscarriage, ectopic
pregnancy, placenta abruption, praevia and accreta,
respiratory problems including persistent pulmonary
WHO: Beyond the Numbers
“Knowing the level of maternal mortality is not
enough; we need to understand the underlying
factors that led to the deaths.
“Each maternal death or case of life-threatening
complications has a story to tell and can provide
indications on practical ways of addressing the
Perinatal Audits
Individual Audit
Responsibilities when publishing the
Without giving context and precautions
about how “the numbers” will be used
Implications for the way “science” is used
Repercussions for American women on
Repercussions internationally on women’s
choice in VBAC
Repercussions Internationally
ACNM VBAC protocols – out-of-hospital
Are American standards based on research?
Reconsider what access to “immediate”
caesarean section means
Society of Obstetricians and
Gynaecologists of Canada
The word “timely” has replaced
30 minutes is timely enough
Choice of birth place is multi-factorial,
based on science, liability, culture
Evaluate where risks are to inform women
and caregivers
1. Lieberman E, et al. Results of the national study of
vaginal birth after cesarean in birth centers. Obstet
Gynecol. 2004;104:933-42.
2. Maternity Center Association. What Every Pregnant
Woman Needs to Know About Cesarean Section. New
York: MCA, 2004.
3. Landon MB. et al. Maternal and perinatal outcomes
associated with a trial of labour after prior cesarean
delivery. NEJM. 2004;351(25);2581-89.
4. Johnson KC and Daviss BA. Re:Results of the national
study of vaginal birth after cesarean in birth centers. Obstet
Gynecol. 2005 in Press April 2005.
Letters to the editor re Lydon-Rochelle
in BMJ December 2001
Daviss BA
1. Study’s focus on induction v spontaneous labour neglects
spontaneous delivery
(Study did not provide comparison group of women with
no intervention because did not stratify for oxytocic use)
Johnson K, Gaskin I
2. Safety of single-layer suturing in caesarean sections must
be proven (the apparent increase in TOL rupture rates in the
1990’s may have been caused by a change to single layer
suturing of the uterine incision – not evidence based)
Letters to the Editor re Lydon Rochelle
in NEJM Jan 2002
Heffner, L. Brigham and Women’s hospital
3. Study doesn’t provide incremental risks (absolute risks) of
perinatal mortality with each category of delivery, only the
relative risk of infant death should rupture occur
Incremental Risk:
Csect: 0.09 deaths per 1000
Spontaneous Labour: 0.28 deaths per 1000
VBAC Induction: 0.47 deaths per 1000
2% increase in perinatal mortality from 5.2 to 5.4 per 1000
Bottom Line: Study suggests non-induced VBAC may result in
less than 1 excess death per 5,000 births
Letters to the Editor re Lydon Rochelle
in NEJM Jan 2002
Weiss J, Bartlett, L Massachusetts Dep’t Public Health
4. Diagnostic codes (ICD 665.0 and 665.1) to identify
uterine rupture not used exclusively for ruptures.
Massachusetts’ study – with chart review:
½ of those coded to 665.0 & 665.1 – not ruptures
1/3 of ruptures missed – (coded using ICD Code 674)
Letters to the Editor re Lydon Rochelle
in NEJM Jan 2002
Magee, D
M.D., Massachusetts
8. Critiques Greene’s assertion that “most reasonable
women… would choose a caesarean if told uterine rupture
raises the risk of infant death by a factor of 10,” by
reminding readers this is a relative risk in a rare event.
Suggests instead the data from this particular article should
be presented as: “the rate of perinatal death with a repeated
cesarean is just over 3 in 1000 births; if you choose to have
a trial of labour, the rate is just below 6 in 1,000 births.
Letters to the Editor re Lydon Rochelle
in NEJM Jan 2002
Koroukian, S, Case Western Reserve University, Cleveland
7. Re-Green’s editorial: Greene discussed
informed consent. Will the information presented
to women undergoing primary caesarean include
the increased risk of uterine rupture in future even
without the spontaneous onset of labour? And the
near certainty of caesarean next time?
Conclusion on VBAC Issue
Study conclusions of questionable merit are being used in isolation
rather than as part of a synthesis of the literature
Publicity, not always merit, is dictating which studies become
Letters to the editor do not seem to be able to undo the political
drive to increase interventions based on these studies’
The more credibility the questionable studies are given the more
intervention will be subsequently required

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