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Lauredhel is an Australian woman and mother with a disability. She blogs about disability and accessibility, social and reproductive justice, gender, freedom from violence, the uses and misuses of language, medical science, otters, gardening, and cooking.

This author has written 1617 posts for Hoyden About Town. Read more about Lauredhel »

25 responses to “That Homebirth Study in South Australia”

  1. cim

    So the total rate of death for planned home births is statistically indistinguishable from the rate for planned hospital births but the rate for a particular cause of death is statistically significantly higher for planned home births. Therefore, the rate for other unspecified causes of deaths must be higher for planned hospital births, which means that the same data and methodology, but picking a different cause of death, would show that hospitals were really risky (for that cause).

    I think the extrapolation from “1 death” to “greater risk for that cause of death” is statistically sound, though – the 95% confidence interval stretches from 1.81 to 103.7 – it’s not possible to say with any certainty at all how much riskier giving birth at home is, but it is possible to say that, were it equally risky, it would be very unlikely that there would have been any deaths at all. Of course, highlighting this particular cause when the all-cause death rate is essentially identical gives a very misleading impression.

  2. AMM

    I think the extrapolation from “1 death” to “greater risk for that cause of death” is statistically sound, though

    I disagree. With such small numbers, the idea of applying statistical methods is nonsense. The premise of all statistical methods is that you have large samples, large enough to swamp out the noise. In this case, you have a sample of 1. In order to come up with a meaningful number for the actual risk, you’d have to have, say, 100.

    I mean, even the numbers themselves indicate that they should at the very least be taken with many grains of salt. Look at that range: “1.81 to 103.7″.[*] That’s really saying that they don’t even know the order of magnitude of the “true” risk ratio. It’s saying that it is probably not as big as 1000. The lower number is statistically meaningless, but since there was one death, you know the risk isn’t zero. That’s all you know.

    The people who wrote the article obviously don’t have a clue about statistics (or they chose to ignore it), they just plugged the data into a statistics program and blindly copied the output into the article, spurious precision and all. After all, the computer never lies, right?

    [*] Imagine if someone told you that a tree’s height was “between 1.81 to 103.7 feet.” How seriously would you take the “1.81″? Or the 3.7?

  3. Kristian

    Hi, thanks for this! Especially in context of this article I read immediately after yours, if you haven’t seen it already:

    http://www.news.com.au/national/overdue-pregnant-nsw-woman-gets-police-check-up/story-e6frfkvr-1225820277538

  4. The AMA trots out another media bonanza piece of crap » Janet Fraser - Where birth and feminism intersect.

    [...] out Lisa Barrett’s blog and Hoyden About Town for a full breakdown. I also look forward to hearing from Henci Goer on this [...]

  5. beloved

    Thank you for this brilliant piece. Now if only we could convince journalists that reading past the synopsis and the press release might be worth their time.

  6. Ali

    Thank you for this piece. I feel so very tired and exasperated at the medical establishment’s propaganda campaign against homebirth and the fact that so many people seem blissfully content to let it all happen. Thank you again.

  7. mockturtle

    I disagree. With such small numbers, the idea of applying statistical methods is nonsense. The premise of all statistical methods is that you have large samples, large enough to swamp out the noise. In this case, you have a sample of 1. In order to come up with a meaningful number for the actual risk, you’d have to have, say, 100.

    The sample size for planed homebirths that occurred at home isn’t 1, it’s 792. However the number of events within that sample group is 1. The distinction is important because the analysis isn’t done on the number of events, it’s done on the odds/risk which are calculations from the sample based on the contrast between events and non-events. A small number of events, as seen here, doesn’t create a problem for noise (which is dealt with in ways beyond pure size of study – “large enough” is certainly more appropriate than “the bigger the better”), though it will render certain methods of data collection and analysis more appropriate than others.
    (You probably know all this – but i thought I’d break it down a little for those who don’t)

    I mean, even the numbers themselves indicate that they should at the very least be taken with many grains of salt. Look at that range: “1.81 to 103.7?.[*] That’s really saying that they don’t even know the order of magnitude of the “true” risk ratio.

    While I absolutely agree with the first sentence, the size of the range isn’t implying that at all. It’s just saying that they can’t be very sure or specific about it.In my experience stats is more about finding what isn’t true than what is, so the range is always indicative even when it’s so large that you can’t be confident (heh) about the true answer. So in answer to the tree question, I don’t think I’d have quite the response you’re looking for. ;)

  8. Ariane

    I saw an article in the Terror today which seemed to indicate that a hospital had sent police to the house of a woman who had refused a hospital induction whilst also under the care of a private midwife and intending to have a home birth. I didn’t read it in detail (it’s the Terror after all, who knows whether there’s any truth in it anywhere?) but I frankly don’t care if she was bungy jumping, no-one gets to over-ride her decisions about that baby until it’s born. There has to be a line in the sand at which the interests of the baby are allowed to be considered independently of the mother’s, and I can’t imagine any line other than when the baby is, in fact, independent of the mother by means of birth.

    In terms of this study, the 1 isn’t enough to convince me. Yes, it’s outside the 95% confidence interval, but stats on the whole is not good with outliers. This one may or may not be an outlier, but there’s nothing in the data to say either way. Physical sciences “untainted” with free will throw up outliers. So I agree that the sample size of the event doesn’t generally matter, but I can tell you that I’m not going to be convinced by one Higgs Boson (which will, if it is found, be found by looking for events in sample sizes of gazillions).

  9. Linda McHale

    Such blatant hatred,,,, or maybe FEAR is the real feeling that the doctors have for the midwives. The state of mind that accepts birth and respects women can’t be held in the same mind that holds fear of birth and women. I wish they would stop their fear campaign and sign on to real caring. They might actually become fulfilled and happy in their work.

  10. lauredhel

    The press has started up today as expected, complete with the outright lies you’d expect from someone who just read the AMA press release and didn’t bother with the source:

    However, babies were seven times more likely to die from complications during a homebirth than a planned hospital delivery.

    This isn’t just twisted statistics and poor interpretation; it is outright untrue.

  11. Weekly News Round-Up, 1/17 « Women’s Health News

    [...] Lauredhel at Hoyden writes about another study I haven’t yet read, That Homebirth Study In South Australia. [...]

  12. David Jackmanson

    I’m working on a story for 4ZZZ-FM news on Monday morning, (and, I hope, a longer one for the current affairs show Brisbane Line on Tuesday afternoon) based on the analysis here. Having looked at the report, two lines jump out:

    “Although our study has shown few adverse outcomes from planned home births in SA, small numbers with large confidence intervals limit interpretation of these data”. [Doesn't that mean that any interpretation either way should be limited?]

    “Nonetheless, in the 16-year study period there were only three perinatal deaths for which one can reasonably assume that a different choice of care provider, location of birth, or timing of transfer to hospital might have made a difference to the outcome.”

    I’m also trying to grasp the idea of confidence levels. The confidence intervals of 1.53-38.57 for the sevenfold risk and 8.02-88.83 for the 27-fold risk seem remarkably large.

  13. David Jackmanson

    Also,

    “Infants born after transfer to hospital were three times more likely to have an Apgar score of < 7 at 5 minutes than infants from planned hospital births"

    Presumably infants born after transfer to hospital are going to be in the highest category of risk for low Apgar scores. If they looked like they were going to be fine, they wouldn't be transferred to hospital, and if they looked like they were going to have problems they would be transferred, and so lower Apgar scores would be far more likely.

  14. Australian Medical Association’s misleading spin on homebirth deaths exposed by @hoydenabouttown blog « 4ZzZFM NEWS

    [...] misleading spin on homebirth deaths exposed by @hoydenabouttown blog Jump to Comments The Hoyden About Town blog has criticised the Australian Medical Association’s presentation of a study on deaths during homebirth in [...]

  15. Emma Someone
  16. lauredhel

    David: Yes, it makes no sense to try to prove any sort of point about anything with the post-transfer Apgar scores. There is no data on a group of planned hospital births in which major complications occurred, so there’s no appropriate comparison group.

    You need to also take a closer look at those “three intrapartum asphyxia” deaths in the ‘planned home birth’ group. Two occurred in hospital. And we also need to take a close look at why two of the women in the study chose to delay transfer to hospital; how about a root cause analysis involving previous horrendous experiences in hospital? Either way, “Midwives are dangerous!” is not the message.

    The homebirth have been closely scrutinised. How about let’s apply the same scrutiny to the hospital births, if we’re serious about saving lives? There are far far more deaths in hospital; if intrapartum asphyxia is preventable, as the AMA seems to be saying, then adjustments to care there has the potential to save many more – 87, in this sample. 87 intrapartum asphyxia deaths in hospital. Why is the media producing conspicuous grief and concern over one baby dying at home, and ignoring the 87 intrapartum asphyxias in hospital? Why are they not questioning the massive increase in surgery and injury that occurs in hospital for no improvement in perinatal death rate?

    There is a take-home message from this study, and it’s exactly the same as for the recent Canadian study. The medical profession likes to scream about dead babies and bleeding mothers in its ongoing fight against losing “control” of birth. This home birth group was not a carefully selected low risk group – it included women with twins, previous C sections, post-term pregnancies, fetuses with known lethal anomalies and so on. Yet, the perinatal mortality and postpartum haemorrhage rates in the planned homebirth and planned hospital birth groups were exactly the same. The homebirth group achieved this superbly low perinatal mortality with far fewer operations and half the neonatal intensive care. If past studies can be drawn on, this means they likely also achieved this superbly low perinatal mortality – the same perinatal mortality that the AMA crows about as being among the ‘best in the world’ – at low costs and with greater satisfaction of the people involved.

    But you won’t see that in the papers.

  17. chloe

    Thank you very much for posting very informative, however it still dosent asnwer the question as to why the AMA is trying to force hospital confinement upon pregnant women, whilst the rest of the population still has the basic civil, legal right to refuse treament. Why is it i can refuse chemo if i have cancer, but i am required by law to birth my baby in a clinical frightening environment where i am at the very least ten times more likely to pressured into unecessary medical procedures. This law is a blatant abuse of the rights of women to their own bodies, whats next, abortion becomes outlawed and the fetus is given legal rights so that every woman who aborts is accused of murder. Is this just a case of an overcontrolling medical assosiation and a religiously biased government body? It certainly makes me wonder?

  18. MomTFH

    Thanks for this.

    I think the statistical concept that is relevant to this discussion is power and effect size. A study has to have an adequate number of subjects to have adequate power and adequate effect size.

    The smaller the difference you are looking at, (say, one in more than 1000), the larger the N necessary.

  19. Rebekka

    Chloe, as I understand, this isn’t the case: “Why is it i can refuse chemo if i have cancer, but i am required by law to birth my baby in a clinical frightening environment where i am at the very least ten times more likely to pressured into unecessary medical procedures.”

    Don’t get me wrong, I’m 100% against these laws – midwifery should be the standard of care. But what the laws do is essentially outlaw homebirth midwifery – they do *not* force women to birth in a clinic, nor do they mean you can’t refuse treatment. The laws do not outlaw unassisted homebirth.

  20. AMA misleads on homebirth death figures: Interview w AMA Pres + Home Birth Australia Sec « 4ZzZFM NEWS

    [...] a journal article claiming a seven-fold increase in risk of death for children born at home. The Hoyden About Town blog published an article explaining how talking about the seven-fold increase…, as it involved only nine deaths over a thousand planned homebirths in fifteen years. The study [...]

  21. lauredhel
  22. Graham

    Seems pretty poor evidence – I’m far from a methodological purist, but if ever there was a need for an RCT to establish safety, this was it. There are so many potential confounding variables and differences between the home and hospital groups that any comparison is highly suspect (even if obvious risk factors are adjusted for). There are longstanding calls for an RCT of home v hospital birth (e.g. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2350434/), but recruitment tends to be problematic, because of resistance to randomisation (e.g. http://www3.interscience.wiley.com/journal/122206818/abstract).

  23. The Down Under Feminists Carnival is here! « The Radical Radish

    [...] Will You Be Ready For Your First Time? posted at Hoyden About Town. And she also examines That Homebirth Study in South Australia that was blatantly misrepresented in the media, also at Hoyden About [...]

  24. Ninth Carnival of Feminist Parenting « Mothers For Women’s Lib

    [...] talks about That Homebirth Study in South Australia, and how the data has been skewed by the obstetric community to mean something totally different to [...]

  25. Ninth carnival of feminist parenting « Spilt Milk

    [...] And if you weren’t already skeptical about the AMAs anti-homebirth position, you will be after reading Lauredhel’s explanation of That Homebirth Study in South Australia. [...]

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