New Survey Shows High Success Rate for VBAC’s at Home

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by Karen Troy, PhD

The Midwives Alliance of North America (MANA) recently published data from a large and well-tracked series of planned home births, the result of a home birth registry program that was initiated in 2004 (1).  The data set included nearly 17,000 planned home births attended by a mix of midwives including CPMs (79%), CNMs (15%), and other unlicensed midwives.  Within this cohort were 1054 women with a history of cesarean section who were planning a vaginal birth after cesarean – VBAC – at home. (This is also referred to within the birth community as “HBAC” – home birth after cesarean).   Within this subgroup, 87% had successful vaginal births, with 94% of those births occurring at home and the remaining 6% occurring after a transfer to a local hospital.  This success rate is substantially higher than the 60-80% success rate reported across other large hospital-based cohorts (2) and likely reflects the high level of commitment to and support of natural birth, both from the mothers and their care providers.

The primary risk for women undergoing a trial of labor after a cesarean (TOLAC) compared to women with no history of a cesarean is uterine rupture, which can result in morbidity and mortality to mother and baby.  The American College of Obstetrics and Gynecologists estimates the overall risk of uterine rupture in women with a single low transverse cesarean scar to be approximately 0.7% (3) based on large hospital-based studies. For this reason, ACOG recommends that operating facilities be “immediately available” during TOLAC, a policy that has limited access to VBAC within smaller hospitals, and prevents many women with a history of a cesarean from choosing an out of hospital birth.  In the cohort reported by MANA, the intrapartum fetal death rate was significantly higher for women with prior cesarean compared to those without a history of cesarean (2.85/1000 versus 0.66/1000). For comparison, neonatal death rates for repeat cesarean and hospital VBAC were 1.03/1000 and 0.84/1000, respectively in one recent large series of low-risk births (4), and others have reported mortality rates of 1.77/1000 for primary cesarean births (5).

We at the International Cesarean Awareness Network (ICAN) find these statistics encouraging and applaud the Midwives Alliance of North America for collecting and presenting this data.  The data show that low-risk women who plan a VBAC at home have a high rate of success and a low rate of complications.  We believe all women have a right to choose their location of birth, and out of hospital birth can be safe for many women with a prior cesarean.  The data presented here give mothers important information that can help them understand the risks of HBAC so that they can make informed decisions in partnership with their care providers.  ICAN strongly encourages all women with a prior cesarean to educate themselves about birth options.  We believe that a more well-integrated and established continuity of care system that facilitated home to hospital transfers would improve home birth, and especially HBAC, safety.

The full study can be found here:

http://media.wix.com/ugd/7a9bd8_dccd61656b3346ca9647db9252cf389a.pdf

(1)  Cheyney M, Bovbjerg M, Everson C, Gordon W, Hannibal D, Vedam S. (2014) Outcomes of care for 16,924 planned home births in the United States: The Midwives Alliance of North America Statistics Project, 2004-2009. J Midwifery and Women’s Health 00:1-11 doi:10.1111/jmwh.12172

(2) National Institutes of Health Concensus Development conference statement: vaginal birth after cesarean: new insights March 8-10, 2010

(3)  ACOG Practice Bulletin No 115, August 2010 “Vaginal Birth after Previous Cesarean”  Obstetrics and Gynecology Vol 116 No. 2 Part 1

(4) Menacker F, MacDorman MF, Declercq E. (2010)  Neonatal mortality risk for repeat cesarean compared to vaginal birth after cesarean (VBAC) deliveries in the United States, 1998-2002 birth cohorts.  Matern Child Health J 14:147-154

(5) MacDorman, M. F., Declercq, E., Menacker, F., & Malloy, M. H. (2006). Infant and neonatal mortality for primary cesarean and vaginal births to women with ‘‘no indicated risk’’, United States, 1998–2001 birth cohorts. Birth, 333, 175–182.

4 Comments

  1. Kait February 28, 2014 12:37 pm  Reply

    Actually the statistics for this study would be 1/350 chance or 0.002857. Also, this is a finite study and while it can give a good picture of homebirth, it’s still susceptible to the Law of Large Numbers which says the observed percentage of outcomes in a finite number of trials will approach theoretical probability as the sample gets very large. This is also on a logarithmic scale. For complete accuracy we would need 1 million to 1 billion sample size.

  2. Sarah February 28, 2014 1:12 pm  Reply

    Love this! Good job at making the study easy to understand in relation to HBAC! I’d also like to point out that study shows that first time moms experience similar occurrence of neonatal death as VBAC moms in a home setting. I found this interesting because in IL it’s difficult to find midwives that will attend HBACs, but those same midwives will attend first time moms at home.

    Kait, a bigger sample would be great, but I wonder how many TOLAC home births there were over the time frame of the study… I can guarantee not 1 million. And I’ve never seen any birth study with a sample size that large. So, I’m not sure this isn’t an accurate sample without knowing how large the specific population was. Just to clear up confusion I had, 1/350 is the same as 2.85/1000 – for a second I thought you were saying it was sited incorrectly :)

  3. Kait February 28, 2014 6:21 pm  Reply

    Hi Sarah

    My comment seems really weird now because I was responding to someone else who has apparently deleted her comment. She was against homebirth saying that 1/200 babies would die, so I was clearing that up for her. (This is where the 1/350 comes in)

    I think this is an excellent article and that it gives us a good picture of homebirth even though all studies have variables to consider.

  4. Karen March 3, 2014 12:35 pm  Reply

    Kait, I agree the study has some limitations and in terms of sample size it’s substantially smaller than the hospital studies. It’s not perfect, but what I think is important is that it’s the first real step I’ve seen anyone take to assemble and report the data. What women and care providers choose to do with the data we cannot say, but at least now there are some hard numbers available to understand risk — a key prerequisite to making an informed decision. In terms of how the numbers are phrased — 1/350 versus 2.85/1000, I think stating these sorts of statistics in multiple ways is really helpful for people to wrap their brain around the numbers, so thanks for putting it into another context.

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