Tuesday, May 6, 2014

HBAC

Let's discuss HBAC a little more. Again, for those not familiar with the acronyms:

VBAC -- Vaginal Birth After Cesarean
HBAC -- Home Birth After Cesarean
TOLAC -- Trial Of Labor After Cesarean (attempting a VBAC)
ERCD -- Elective Repeat Cesarean Delivery
RCS -- Repeat Cesarean Section

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April 4, 2017 Update: a new study from the Midwives Alliance of North America (MANA) confirms that attempting a VBAC at home comes with a much higher risk of neonatal death. The study Perspectives on risk: Assessment of risk profiles and outcomes among women planning community birth in the United States looked at planned, midwife-attended births in a home or freestanding birth center. (Note: in the study, they use the term LAC (Labor after Cesarean) instead of using the term TOLAC or attempted VBAC.)
Here are the neonatal mortality rates for women attempting birth at home or freestanding birth center:
Women with prior vaginal birth, no cesarean history: 1.03/1000
Women attempting VBAC with prior vaginal birth: 1.27/1000
Women attempting VBAC without prior vaginal birth: 10.2/1000

Yes, you read that outrageously awful rate correctly: 10 neonatal deaths per one thousand! Once again, all of these rates are far too high, but especially for women attempting a VBAC who have never had a vaginal birth.

Compare those rates to neonatal mortality rates for USA hospitals: 
Hospital CNMs (lower risk pregnancies) = 0.35/1000 to 0.55/1000
Hospital MDs (higher risk pregnancies) = 0.43/1000 to 0.63/1000
Hospital attempted VBACs* = 1.3/1000
Hospital repeat cesarean = 0.5/1000

The neonatal mortality rate for women attempting a VBAC with a midwife at home or in a freestanding birth center is an alarming, tragically high rate. Far too many babies dying preventable deaths.

* The hospital attempted VBAC group includes a higher risk group of women. It includes women with and without prior vaginal birth, with and without higher risk medical conditions and also includes fetal deaths - death of baby in uterus prior to onset of labor from 28 weeks gestation and beyond. Fetal deaths and higher risk pregnancies were not included in the home and birth center rates above (meaning, the mortality rates would be even higher for the home and birth center births if they were included).


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Perhaps you are wondering if 1052 HBACs in the MANA study is a large enough sample to draw any conclusions?

In short, the answer is yes. In long, keep reading.

I posed a question regarding this matter to a few experts: 2 doctors and 1 statistics professor. Is it possible that the increase risk of HBAC is due to chance? They each agreed that the increased risk is far too high to be due to chance, even considering the sample size of 1052. Statistical power comes into play here, which is affected by various factors - an important factor being the magnitude of the effect. Since the effect in this case is large, a sample size of 1052 births is adequate.

Here's what the statistics professor had to say about it: "Short answer: The [MANA HBAC] data set as a whole is not too small. The breech and VBAC groups are not too small. The preE and gestational diabetes groups are. The 1052 HBACs are too small a number to be totally sure what the risk of HBAC at home birth is, but it is NOT too small to be sure that it is much worse than hospital VBAC. It's kind of like, "I don't know exactly what breed that dog is, but it isn't a cat." Specifically, we can be 95% sure that the true probability of baby death from HBAC is AT LEAST 0.0025, that is, 2.5 deaths per thousand attempted HBACs with full-term babies."

And the response from one of the MDs: "It would be reasonable to argue the sample size is too small if one were arguing that you cannot draw any conclusions if, say, we were comparing a hospital death rate of 4/1000 and a homebirth death rate of 5/1000. The small homebirth sample size might mean that relatively small increased risk in the homebirth group was due to chance and that if we looked at 2000 HBACs, the death rate might be only 4/1000. But it is another thing entirely when the death rate in the HBAC group is astronomical. When the increase risk is dramatically higher, it is statistically unlikely to be due to chance."

Due to the huge increase of risk noted in the home TOLAC group (4.75 infant deaths per one thousand) versus the hospital TOLAC group (1.30 infant deaths per one thousand), we know it is far too high to be due to chance. It is due to the increased risk of attempting a VBAC outside of a hospital.

Another way to address this issue of sample size is to repeat the same study and see if the results are similar. And we can already do that. This is the second study done in the USA that addresses out-of-hospital attempted VBACs. The first was published in 2004 by the American College of Obstetrics and Gynecologists by Lieberman, et al.



The authors are two doctors and 3 midwives, including Kitty Ernst and Judith Rooks - two very well-respected nurse midwives. The study looked at out-of-hospital attempted VBACs in birth centers.

In the Lieberman study, there were 1453 labors/births. Let's compare the mortality rates to the MANA study:

Lieberman study = 4.82/1000
MANA study = 4.75/1000

Nearly identical results.

This increase risk (again, compared to the mortality rate of 1.3/1000 for hospital attempted VBACs) is not due to chance.

If you still don't believe that out-of-hospital attempted VBAC isn't substantially, horrifically riskier than hospital attempted VBAC.... then it's because you just don't want to.


HBAC... are there other risks?

In my first post regarding this issue, I said "Coincidentally, the MANA study infant mortality rate for HBAC mothers is consistent with the risk of uterine rupture (5 babies out of 1052 died in the MANA study; risk of uterine rupture is 5 per 1000). It is possible that all 5 deaths were due, directly or indirectly, to uterine rupture." So is it possible that all 5 deaths out of the 1052 attempted VBACs were due to complications from uterine rupture? Yes, it is. But we don't know. Because the MANA study authors neglected to provide information about the deaths. So let's look at other reasons why attempting a VBAC in an out-of-hospital setting is riskier. What risks are to be considered for a woman choosing HBAC ?

1. Risks of birth. Period. For any woman, giving birth in any setting, regardless of mode of delivery, regardless of birth attendant, regardless of intervention, there are risks inherently involved with childbirth. Shoulder dystocia, cord prolapse, fetal/neonatal hypoxia, placental abruption, congenital anomalies that require immediate access life saving equipment, etc. Birth is not without risk, no matter where birth takes place. There will be a certain amount of deaths that occur in all birth settings.

2. Risks of home birth in the USA. Home birth here in the States in and of itself is far riskier than hospital birth. Not a single study done on home birth here in the States supports home birth as an equally safe option to hospital birth -- not even the MANA study, not even for low risk women. There is also the 2015 New England Journal of Medicine study2014 Cornell study, the 2013 Grunebaum study, the 2013 Cheng study and the CPM2000 study. Each of the studies addresses planned, midwife-attended home births. Each show a dramatic increase risk for home birth. Home birth in the USA is not like home birth in any other first world country. Different system, different midwives.

3. Risk of placental abruption and placenta praevia. As discussed in the Lieberman study and here in this 2009 study by Yang et al., women with a previous cesarean section are at an increase risk for placental abruption and placenta praevia. These are life-threatening complications that require immediate medical help.

4. Risks of uterine rupture. We don't know the mortality rate specifically for uterine ruptures that occur in an out-of-hospital setting, but we do know that the baby needs to be delivered within 10-37 minutes. Information currently available regarding mortality rate for uterine rupture for attempted VBACs is for in hospital attempted VBACs. If you've ever been a part of a home birth transfer to a hospital (I have), you know that getting a laboring woman in a car (or ambulance), transferred, assessed at the hospital, prepped, and into an operating room takes a pretty good chunk of time.

5. Lack of Monitoring. Using a handheld Doppler monitor or a fetoscope is not the same as using Continuous Electronic Fetal Monitoring (CEFM). For women attempting a VBAC, CEFM is recommended by the ACOG (American College of Obstetricians and Gynecologists), American Academy of Family Physicians, RCOG (Royal College of Obstetricians and Gynaecologists), and SOGC (Society of Obstetricians and Gynaecologists of Canada). Maternal pain, bleeding, and other signs/symptoms are not as common as fetal heart rate abnormality when uterine rupture occurs. According to the latest research provided in the Guise study and from the VBAC bulletin of ACOG, fetal heart tracing abnormalities is the most common reported sign of uterine rupture.


Bottom Line: Attempting a VBAC outside of a hospital is risky business. If someone is telling you otherwise, it's because they either don't know about the increased risk or because they don't want you to know about the increased risk. 3-4 babies per 1000 dying preventable deaths is far too high. And for a woman attempting a home VBAC who has never had a vaginal birth before? At best, her baby has an increase risk of dying that is 8 times higher than attempting a hospital VBAC.




6 comments:

  1. And yet the supposed "expert" on VBAC, Jen Kamel, had a HBAC and thinks that anyone who says it's more dangerous than hospital VBAC is fear-mongering. She doesn't think that the MANA data is meaningful, well, because MANA said so. And yet it essentially duplicates the results found by Lieberman.

    If you are contemplating a HBAC and think that you have been educated about the risks at VBAC facts, you should think again.

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  2. I wouldn't take a medicine that increases my risks for a serious complication by 3-4 per 1000 people taking it. That is a large chance.

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  3. I completely agree that HBAC risks are astronomical and that the only place where a TOLAC should be attempted is a hospital. But there are two barriers to asking all HBAC'ing mothers to consider a hospital instead:

    (1) VBAC bans. Some women do not have access to a local hospital that will support a TOLAC, even when they are optimal candidates for it, so rather than sacrifice their bodily autonomy and submit to unnecessary surgery, they will go with the riskier HBAC option.

    (2) Hospital staff who will bully and badger a woman into unnecessary interventions or just perform procedures on her without her consent. The recent NYT story about the VBAC'ing mother who was forced to have a cesarean in New York is one dramatic example.

    Anybody who is truly concerned about ending HBAC and persuading all VBAC women to birth in a hospital should be looking to address those two things. Those who don't or won't remind me of pro-lifers who say they want to put an end to abortion, but refuse to address the social and economic factors that often lead women to choose abortion.

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    1. I'm not trying to end HBAC. I'm providing information so that women who are considering HBAC can make a truly informed decision.

      As I wrote above, I do not agree with VBAC bans. Nor do I think it's ok for anyone to be bullied or badgered into anything, anywhere, any time. But that does not mean that until VBAC bans are all lifted, and until all hospital staff can figure out how to be supportive and give personal care, that no one should offer up the truth about the risks of HBAC.

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    2. Hi Dani,

      I think you misunderstand me. I wasn't accusing you of being such a person. You're one of the more balanced persons that I know of amidst the natural birth/homebirth vs. medicated birth debate and I appreciate your blog.

      Of course there's nothing wrong with informing on the risks of HBAC. I just wanted to point out that for a lot of women, there is no "informed choice" to make. The only choice is between (the ironically named) ERCD and HBAC.

      One site that I did have in mind is the SOB Web site. Tuteur is on a mission to end homebirth, but isn't particularly dedicated to ending VBAC bans and outright sneers at those who endure trauma at their hospital births. Seems to me that if she were truly invested in ending risky homebirths, her site would be ground zero for putting an end to VBAC bans and advocating for human rights in childbirth, but it isn't.

      In contrast, NCBers say a lot of things that are full of crap, but they are genuinely dedicated to ending VBAC bans and abuse of laboring women in hospitals, and if you've had an atrocious experience at the hospital, they will listen, sympathize, and try to comfort you.

      Anyhow, I think you do good work here, and thanks for the post on HBAC.

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    3. Thank you for clarifying and I appreciate what you are saying.

      I don't see Dr. Tuteur on a mission to end home birth... but she makes it clear she wants to abolish the CPM credential. She has a lot of respect for CNMs (as a whole) and there are several (including home birth CNMs) who follow and regularly comment on her blog.

      "In contrast, NCBers say a lot of things that are full of crap, but they are genuinely dedicated to ending VBAC bans and abuse of laboring women in hospitals, and if you've had an atrocious experience at the hospital, they will listen, sympathize, and try to comfort you."

      Yes, they will listen and sympathize when you have a bad hospital experience. But on the flip side, if a woman has had a bad home birth experience, she's often cast aside, encouraged not to share her story, told she is a fear mongerer, etc etc.

      "[Tuteur] outright sneers at those who endure trauma at their hospital births." can you give an example? I'm in a few groups on Facebook that Dr. Tuteur is in and women have shared bad hospital experience stories and she has been supportive. I've also read on her blog her own issues with hospitals / the medical system (I believe the post I'm thinking of specifically had to do with her dad??). She just recently wrote about how wrong it was for that doctor to perform a c-section on that woman without her consent.

      "Of course there's nothing wrong with informing on the risks of HBAC. I just wanted to point out that for a lot of women, there is no "informed choice" to make. The only choice is between (the ironically named) ERCD and HBAC. "

      For women to be forced to make that choice is awful. It's AWFUL. The choice is limited but it's still a choice and they deserve to know (unbiased) risks/benefits of each. But I have seen a lot in forums and on the internet that HBAC risks are blown off and/or minimized, that the MANA data for HBACs is ignored, etc... and that's not right.

      "Anyhow, I think you do good work here, and thanks for the post on HBAC."

      I appreciate that greatly and your thoughts as well. :)

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