Midwives use dubious math to promote themselves

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Suppose you wanted to do a study that showed that a larger role for midwives could improve US healthcare outcomes. Imagine that you believed in your heart of hearts that midwifery care was better and you were sure that statistical analysis would prove your claims. Or, if you are cynical like me, imagine that you were intent on increasing midwife employment opportunities and you planned to massage the data until it showed what you wanted.

Where would you start?

The point of the paper is to try to create a relationship between midwifery and outcomes no matter how spurious or tenuous.

I know! You’d start by showing that outcomes improve as the numbers of midwives increase. You could show what happened to infant mortality as the number of midwives decreased dramatically in the early 20th Century and rose steeply at the end.


Oops! This shows that infant mortality dropped steeply as the number of midwives decreased sharply and that the increase in midwives at the end of the 20th Century had little to no impact.

Let’s look at maternal mortality.


That certainly doesn’t show that midwives improve outcomes. Moreover, US maternal mortality appears to have risen in the early 21st Century as the role of midwives increased (not shown).

Drat! I know. You could look at the density of midwives in each state and compare it to outcomes.

Here’s the density of CNMs per state:


And here’s perinatal mortality rate by state:


Dammit! That doesn’t prove the point, either. There are states with lots of CNMs that have poor mortality rates (Maine, Colorado) and states with few CNMs that have excellent outcomes (Nebraska, Iowa).

I’ve got it! You could create a composite score for midwifery integration and massage the components until it shows what you wanted it to show! That’s just what midwives have done.

The new paper is Mapping integration of midwives across the United States: Impact on access, equity, and outcomes by a group of authors containing Holly Powell Kennedy, former head of the American College of Nurse Midwives, Melissa Cheyney, forder Director of Research for the Midwives Alliance of North America, Marian MacDorman, Editor of the Lamaze owned Birth: Issues in Perinatal Care, and Eugene DeClercq, advisor to Ricki Lake on The Business of Being Born.

You’ll never guess what they found!

Using a modified Delphi process, we selected 50/110 key items to include in a weighted, composite Midwifery Integration Scoring (MISS) system. Higher scores indicate greater integration of midwives across all settings. We ranked states by MISS scores; and, using reliable indicators in the CDC-Vital Statistics Database, we calculated correlation coefficients between MISS scores and maternal-newborn outcomes by state …

The MISS scoring system assesses the level of integration of midwives and evaluates regional access to high quality maternity care. In the United States, higher MISS Scores were associated with significantly higher rates of physiologic birth, less obstetric interventions, and fewer adverse neonatal outcomes.

Who could have seen that coming??!!

Nina Martin of ProPublica reports on the results:

Now a groundbreaking study, the first systematic look at what midwives can and can’t do in the states where they practice, offers new evidence that empowering them could significantly boost maternal and infant health. The five-year effort by researchers in Canada and the U.S., published Wednesday, found that states that have done the most to integrate midwives into their health care systems, including Washington, New Mexico and Oregon, have some of the best outcomes for mothers and babies. Conversely, states with some of the most restrictive midwife laws and practices — including Alabama, Ohio and Mississippi — tend to do significantly worse on key indicators of maternal and neonatal well-being.

Sounds impressive on the surface, but if you dig deeper, you find a lot of problems with the analysis.

The most obvious problem is related to race. Since African Americans have 3X higher rates of perinatal and maternal mortality, we KNOW that the mortality rates in each state are related to the proportion of African Americans within the state. Let’s compare the midwifery integration scores to the “whiteness” of each state.

Here’s the midwifery integration scores:


Here is the “whiteness” of each state (created by inverting the colors on a map of the proportion of African Americans per state):


Although it doesn’t map exactly, it’s pretty clear that the whiter the state, the greater the midwifery integration. That’s not surprising since midwifery in the US is almost exclusively the province of white women. So while it looks as though midwifery integration is correlated with better outcomes, the reality is that midwifery integration is correlated with race and it is RACE that is correlated with outcomes.

That is not the only way that the authors have played fast and loose with the truth. Remember, the reason this paper exists is precisely because there is NO direct relationship either historical or by state, between the number of midwives and childbirth outcomes. The whole point of the paper is to try to create a relationship no matter how spurious or tenuous.

The authors created a composite score of maternity integration.

Using a modified Delphi process, we selected 50/110 key items to include in a weighted, composite Midwifery Integration Scoring (MISS) system.

What does that mean? It means that the authors convened a group of people deemed experts to decide what constituted midwifery integration and to give different weights to different factors.

They offered this example:


What is a summary score?

Summary scores combine many measures into one “overall” score, even though the individual measures may address quite different aspects of quality. While composites include a few measures that are highly related, a summary score reflects many more measures that may address different issues. However, all the measures are about a single specific provider or service.

What is weighting?

Summary scores must either give the same “weight” to all the measures they include or give some measures more weight than others. Weightings inherently involve judgments of what is more important and consequential. Individual report users may have different views on this than report sponsors, so the summary score may not reflect their preferences.

As you might imagine there are serious limitations to creating a weighted scoring system.

Sponsors who decide to set weights will need a strong rationale for their decision. Tips for weighting the measures include the following:

Involve people with multiple perspectives (clinicians, patients, managers, and payers) in setting the weights to make sure they are not biased in the direction of a single group’s perspective…

As the brief example offered by the authors demonstrates, weighting is deeply subjective. The authors of this study offer no rationale for weighting outcomes. Moreover, weighting offers an easy way to manipulate the data. Correlations that otherwise would not exist can be created by careful manipulation of relative weights.

The validity of a composite scoring system can be evaluated but as far as I can determine, the authors made no attempt to validate their scoring system.

The authors conclude (not surprisingly) that “greater midwifery integration” is associated with better outcomes:

This greater integration was significantly associated with higher rates of spontaneous vaginal birth, VBAC and breastfeeding at birth and at six months, as well as lower rates of obstetric interventions, preterm birth, low birth weight infants, and neonatal death…

They give lip service to the fact that correlation is not causation and then proceed to ignore it, spinning all sort of scenarios in which outcomes could be improved and money saved if only there were more jobs and autonomy for midwives.

The bottom line is this: there is NO historical correlation between number of midwives and outcomes and there is NO contemporary relationship between availability of midwives per state and outcomes. In response, midwives have created an unvalidated, subjective scoring system that purports to measure midwifery integration. Adjusting the weights of the variables leads to a possibly spurious correlation between midwifery integration and outcomes, a correlation that in no way proves causation.

What have these midwifery partisans demonstrated (beyond the fact that they are willing to go to great lengths to generated some sort of correlation)? Absolutely nothing.

50 Responses to “Midwives use dubious math to promote themselves”

  1. Tara Coombs Lohman
    February 26, 2018 at 11:30 am #

    Ewwwww…..two thoughts on that lovely little mental picture….1. I am not a chemistry major, but the prostaglandins that work so beautifully on direct contact, i.e. semen via intercourse, Cervidil, Prepidil, are probably going to be denatured on contact with stomach acid, right? Natural prostaglandins, produced by the parietal cells of the stomach, decrease the damage of stomach acid on the lining of the stomach, but the chemicals in semen are not going to survive the stomach environment, are they? And, 2. My husband is so shy he cannot perform with the cat in the room. The idea of us taking such measures to enhance my labor….pretty laughable. Very glad for the IV pitocin going into my vein, thank you.

    • Heidi
      February 26, 2018 at 12:15 pm #

      I think she believed there was a significant amount of oxytocin in it. She was clearly confusing IV pitocin and Cervidil anyway. I think Cervidil has components derived from pig semen but obviously is applied directly to the cervix and not given orally. I think there’s has to be a good reason pitocin is administered via IV though and not given orally but that thought didn’t seem to happen for her. I do wonder if the midwife wasn’t feeding her these BS beliefs though?

  2. MWguest
    February 26, 2018 at 3:40 am #

    Meanwhile in Bangladesh, birth moves to the hospital from the home, access to medicine and trained health care providers increases, and neonatal death drops.


    I don’t know how NPR can run that midwife puff piece one day, and this on another.

    • ukay
      February 26, 2018 at 5:33 am #

      Because, deep down, they think they are too special for the laws of nature to apply to them( unlike people in Bangladesh). They are not aware that they are spared because of the medical interventions they so love to decry. To them it must be due to their superiority. That is another reason why the NCB ideology is so racist and classist. (they being not the people at NPR but the people who call themselves progressive when they are just tone deaf and privileged)

    • kilda
      February 26, 2018 at 9:48 am #

      but, but, how can they just medicalize birth like that? I mean, I bet Bangladesh had a very low C section rate, which we all know is the outcome that matters! /s

    • mdcnm
      March 5, 2018 at 5:37 pm #

      Midwives are most commonly the ‘trained birth providers’ used in foreign countries – there are not nearly enough OBs to go around. And the graphs above, created by ACNM, are looking at CNMs, not CPMs – which means most most of those midwives are working in hospitals – not homes. Also, England has much better maternal mortality rates than we do in the US, and they credit midwives with many of those good outcomes, so the authors of this study are not along in drawing their conclusions. There will always be a need for OBs in this world – they do incredibly important work and certainly save lives – but there is also a place for midwives.

  3. Steph858
    February 25, 2018 at 10:24 am #

    Slightly OT: Did anyone else see this news story? http://www.bbc.co.uk/news/uk-wales-south-east-wales-42706652

    Two ways to read that:
    1. Privileged white woman write’s The Onion’s article on homebirth for them.
    2. Midwives suddenly oppose all-natural unmedicated vaginal birth now that they’re no longer invited.

    • Roadstergal
      February 26, 2018 at 11:24 am #

      “Doctors intervene too much, intervention is bad, it ruins the experience and creates problems when natural physiological processes proceed just fine on their own… but wait, you can’t just have _no_ intervention! Come back!!!”

  4. MaineJen
    February 24, 2018 at 2:41 pm #

    Those weighted score criteria are very telling. NOTHING there about patient safety or outcomes. Instead, it’s “Are pretend midwives allowed to do pretty much whatever they want with no supervision, up to and including prescribing medication? Yes? Awesome, you get a high score.”

  5. BeatriceC
    February 23, 2018 at 9:41 pm #

    Sooooo, completely off topic. Y’all remember Lily, the umbrella cockatoo I sometimes birdsit for? Well, her human’s troubles are taking longer to sort out than she had hoped. We signed long term foster care agreements earlier this week, and Miss Lily will be staying here for a little while. There is now an epic battle in progress for control of my left shoulder. https://uploads.disquscdn.com/images/6e9239b1b92c9f75aa7d652215d50686ec30624ab6f537c1224cf0b2445d13cb.jpg

    • Sarah
      February 24, 2018 at 3:10 am #

      The fact that you have a ducks top on seems appropriate.

      • Who?
        February 24, 2018 at 3:14 am #

        Well noticed!

      • BeatriceC
        February 24, 2018 at 12:37 pm #

        Don’t forget to notice the penguins on my pajama pants too! (It’s been really cold and I really like staying in my fuzzy warm pj pants as long as possible these past few days.)

        • Empress of the Iguana People
          February 24, 2018 at 6:42 pm #

          and the parakeet in the cage

          • BeatriceC
            February 24, 2018 at 6:47 pm #

            The lovebird is the one in the cage right behind me. The budgie’s cage is also behind me, but obscured. His cage is on a table between my desk and the window. For obvious reasons, I don’t let the big birds and the little birds out at the same time.

          • Empress of the Iguana People
            February 24, 2018 at 9:28 pm #

            Sorry, lovie, for misidentifying you. Please don’t poop on my quilts 😉

  6. MWguest
    February 23, 2018 at 8:52 pm #

    How is that not abuse?

    • Heidi
      February 23, 2018 at 9:18 pm #

      I don’t think the midwife (the infamous Lisa Barrett I think) forced it on her. In this case, it wasn’t clear if LB even suggested it. It was performed on her own husband. But whatever the case, the birth giver was convinced it was a suitable alternative to pitocin.

  7. MWguest
    February 23, 2018 at 8:38 pm #

    This is embarrassing. Appalling. Revealing of the gross ineptitude of midwives’ understanding of scientific evidence.

    a CNM

  8. Merrie
    February 23, 2018 at 8:35 pm #

    OMFG I can’t stand it. KILL ME NOW. https://www.propublica.org/article/midwives-study-maternal-neonatal-care

    • MWguest
      February 23, 2018 at 8:42 pm #

      Agree. This is crap. Total crap.

  9. yugaya
    February 23, 2018 at 5:34 pm #

    Wow, this is even worse junk science than MANA papers. Cheyney is getting pretty desperate….GOOD.

  10. yentavegan
    February 23, 2018 at 4:32 pm #

    Women like me, women from my socio-economic class are the target audience for studies like” Mapping Integration of Midwives across The United States….”. This study is meant to dazzle me and my ilk with fancy numbers and jargon so that when we brag about how “educated” we are on the topic of midwives/homebirth/birthcenters we can claim the higher ground. I will sheepishly admit that I don’t have the skills to deconstruct the flaws/lies/manipulations of the study. And neither will the women of the crunchysphere who will no doubt sing its praises at the next Seminar of VBAC, ICAN …etc…If given the chance I will re-direct attention to this website..but Dr. Amy is so maligned in the midwife/homebirth/lactation circles they refuse to open their minds to the truth….

    • Anna
      February 23, 2018 at 9:42 pm #

      8000% correct and the few NCB midwives that can read science and do know its bull will sit quietly while the advocates “educate” others.

    • InfiniteSovereign
      February 26, 2018 at 1:49 pm #

      Oh no, you can’t link anything written by Dr. Amy to these people. They are absolutely, 100% closed off to anything she has to say, no matter how factual, accurate, or well supported. I try to find other sources corroborating Dr. Amy’s info and share those when possible, but mostly I don’t bother. It falls on deaf ears. The natural childbirth/ crunchy community is very much a cult. I am an ex-homebirther and still have many friends in the crunchy community. As with other world views, you are expected to but the whole philosophy part and parcel.

      A DEM on my friends list shared the study referenced in the article. She is one who attends twin homebirths. Even many of the most extreme NCBers in our community won’t touch a twin birth . . .

  11. AnotherOor
    February 23, 2018 at 1:11 pm #

    Totally OT, can I comment on the second map, the one of maternal mortality by state? The cartography is horrific! I make maps for a living and it hurts me to see a divergent color scheme used for this data, as well as seemingly random saturation values for the colors used. It’s impossible to tell at a glance which states have higher and lower rates of maternal mortality, and one must constantly refer back to the legend to try and figure out what one is looking at. Tragic. You’d think the CDC could do better but this is what happens when people are taught to use mapping software with no appreciation for or training in cartographic principles. It’s a dying art.

    • Ms. Sweaterfan
      February 23, 2018 at 1:56 pm #

      I went back and looked at the map after reading your comment and you’re totally right – it’s laughably bad! I can’t believe someone decided to go medium blue, then really light blue, then really dark blue in that order?!?!

  12. Sarah
    February 23, 2018 at 12:48 pm #

    Love the assumption that a higher rate of VBACs must be a good thing.

    • Anna
      February 23, 2018 at 9:43 pm #

      Successful VBACs is the important measure in NCB, not the perinatal mortality rate of said VBACs.

      • Roadstergal
        February 26, 2018 at 11:26 am #

        “Successful” meaning “the kid came out of the vagina,” not “the kid is fine.”

  13. Merrie
    February 23, 2018 at 1:08 am #

    I love how that scoring metric lumps CPMs and CMs/CNMs all together as if they are at all comparable. Huge eye roll.

    • AnotherOor
      February 23, 2018 at 1:13 pm #

      Is there anywhere that CPMs have the ability to write prescriptions? I should certainly hope not!

      • Heidi
        February 23, 2018 at 1:57 pm #

        Well, they can write “prescriptions” for castor oil, essential oils, sachets of herbs to plunk in the birthing pool, and a mouthful of semen for the nacheral oxytocin when you are hemorrhaging or have a twin stuck. But no, I’m pretty sure CPMs can’t write actual prescriptions. RNs, who are arguably much more qualified and educated than a CPM can’t write a prescription for a dose of Advil or even a Tums in the hospital. They literally have to have a doctor’s order.

        • February 23, 2018 at 8:46 pm #

          Oh god, a mouthful? Thanks for that visual.

      • MWguest
        February 23, 2018 at 8:46 pm #

        CPMs cannot write prescriptions. This does not prevent CPMs from obtaining and administering prescription medications. Sometimes there are more dicey ways of doing this than others.

        Usually if CPMs are licensed by the state where they are working, there is some way for them to obtain prescription medications – usually oxygen, Pitocin, Cytotec, Methergine, RhoGAM, IV fluids, erythromycin eye ointment, Vitamin K injection.

        (I do not believe that CPMs are adequately trained to administer medications independently.)

  14. BeatriceC
    February 22, 2018 at 4:36 pm #

    Data torture is the bane of my existence. When I was teaching statistics at a community college, I’d always get the “but when are we ever going to use this” question. THIS. This, my former students, is exactly what I meant when I told you that the purpose of my class was not to turn you into statisticians, but to arm you with enough knowledge to call bullshit when an unscrupulous “researcher” attempts to lie to you by manipulating data.

    • PeggySue
      February 22, 2018 at 5:49 pm #

      Totally love the phrase “data torture.” Totally love.

      • Roadstergal
        February 22, 2018 at 7:37 pm #

        “Torture the data until it confesses.” Yep. And the information you get is just as accurate as that extracted from humans in the same manner…

    • Casual Verbosity
      February 22, 2018 at 5:51 pm #

      In my state in Australia it is not currently compulsory to do mathematics in year 11 and 12; the only compulsory subject is English. This suited me well because I always found maths challenging. (It wasn’t until university that I discovered I tend to reverse numbers and put decimal points in the wrong place, so it turns out I’m not as bad at maths as I thought.) However, after studying a crap-tonne (valid metric) of statistics and research methods in my undergrad psych degree, I came to the opinion that I would be all for compulsory mathematics or compulsory science if they offered a course in statistics and research methods. Since we are constantly being bombarded with “science” and asked to use it to make decisions about our lives, I think it’s important that people have enough knowledge to at least be able to spot blatant bull-shit. You don’t necessarily need to be able to calculate the stats yourself by hand, but by learning how the processes work you can recognise when someone is manipulating their data to serve their agenda. I think that is a vital 21st century life-skill.

      • Anna
        February 22, 2018 at 7:53 pm #

        Thats crazy! When I went through in the mid to late 90s we had to do Maths in Year 11 – business math, applied math or general math if we weren’t going for a science or math based uni degree and Maths 1 and 2 if you were. In Year 12 you had to do at least one qualitative experimental for the uni track, but it didn’t have to be Math. I chose biology because I already knew I wanted to do a BA.

        • Casual Verbosity
          February 22, 2018 at 9:02 pm #

          I’m not against non-compulsory mathematics as the form in which maths is taught here at year 11 and 12 level is not really relevant for a lot of people. The general maths course is often regarded as a bit of a farce, and Advanced maths (which is the standard level) is far more complex than anyone will need unless they go into a mathematics or physics based degree. I also think it’s important to give students as much freedom to choose their own subjects as possible to maximise engagement as well as enabling all students to do as well as possible, not just those that are good at the compulsory subjects.

          • Anna
            February 22, 2018 at 9:44 pm #

            True. I personally saw little value in doing maths because I knew what I wanted to do. I would have been up shit creek though had I changed my mind and wanted to do a science based degree. I think there probably should be some Maths in Year 11 at least but thats just a 2cent opinion, not really based on any great wisdom or body of knowledge in the subject.

          • Who?
            February 23, 2018 at 12:59 am #

            My daughter (now an engineer) tutored a lot of high school maths during university (2012-2016). She thought the general maths subject was actually really hard to do well in, and that the hardest subject in senior was the advanced maths subject: harder than physics or the non-mainstream advanced maths subject.

            She encouraged her students who wanted to go to uni to do the advanced maths subject on that basis, as they would work just as hard and get more credits towards their uni entry scores. She turned quite a few non-maths students into maths students in the process.

      • BeatriceC
        February 22, 2018 at 8:31 pm #

        In every US state I’m familiar with, mathematics is only required through grade 11. But that only gets you through basic algebra (split into two years) and geometry. We really need to do a better job for exactly the reasons you described. Honestly, fiascos like Brexit and the current president are caused, in part, by people failing to understand when they’re being manipulated and outright lied to.

        • Casual Verbosity
          February 22, 2018 at 9:04 pm #

          I’m not sure what you’re classing as basic algebra, but in Australia we finished what we would consider to be basic algebra and geometry in the junior years. So if you complete up to year 10 in maths you have got enough of the basics to be able to get by. However, your conception of basic algebra might be different to ours.
          At any rate, we are living in a data-driven society and if people don’t learn how to understand data, then we’re going to see a lot of poor decision making like Brexit and Trump.

          • BeatriceC
            February 22, 2018 at 11:15 pm #

            This gives a rough breakdown of Algebra 1 and 2 in the US, though some of these topics aren’t taught in any real depth, and I disagree that trigonometric functions are taught in Algebra at all. In the US that’s normally taught in a completely separate trigonometry class, or in combined trig/pre-calculus algebra class (that delves more deeply into those scarcely touched on topics mentioned previously.)


  15. mostlyclueless
    February 22, 2018 at 4:06 pm #

    I wonder what causes such stark differences between neighboring states, eg (if I’m understanding the map right) Georgia’s perinatal mortality rate is far lower than neighboring Alabama’s.

    • Roadstergal
      February 22, 2018 at 7:41 pm #

      I dunno, but the data I can dig up on median income has Georgia at #32 and Alabama at #47. (And Mississippi, at #50, has pretty atrocious mortality, too.) I wouldn’t be surprised if there’s also an influence of a combination of high African-American population and fairly entrenched systemic racism…

      • J.B.
        February 26, 2018 at 1:22 pm #

        Possibly reflecting that Atlanta is a huge portion of Georgia’s population.

    • Merrie
      February 26, 2018 at 1:25 pm #

      Probably partly statewide policies, partly Atlanta like someone else said… It is a statewide average. I don’t doubt that there are portions of Georgia that are demographically similar to portions of Alabama and have similar rates.

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