Grounded Parents does a hatchet job on my analysis of the MANA statistics paper


Jamie Bernstein, in a guest post at Grounded Parents, has performed a hatchet job on my analysis of the paper from the Midwives Alliance of North America (MANA), which claimed that homebirth is safe when it’s own data showed the opposite.

The worst part is that Bernstein, described as Skepchick’s resident stats junkie/guru, was incredibly sloppy. There are at least 8 separate errors of fact, of numbers or of math. Frankly, I think Berstein and Grounded Parents owe me an apology and well as owing their readers a correction of the many egregious errors.

Jamie failed to understand the most basic fact about the MANA data. This is not a study; it is a non-randomized survey, which was ignored by more than 70% of the midwives who were supposed to participate. Even then, 25% of the respondents did not provide complete data. Far from being a “study,” this represents MANA’s best efforts to cherry pick it’s own data. That’s what makes the high mortality rate so concerning.

Let’s go through Bernstein’s error one by one:

1. Bernstein wrote: “I clicked the link Dr. Tuteur gave where she got the Citizens for Midwifery quote but didn’t see anything with that quote or numbers on the linked page. I did download and read the study which these numbers supposedly came out of …”

How could you not find it? I gave an exact quote in my piece and linked to the place where the original can be downloaded? It is on page 3 of the 5 page CfM press release, the beginning of the second full paragraph. Please check to confirm.

2. Bernstein wrote: “I’m not really sure exactly where this quote came from and these numbers don’t seem to match anything in the study.”

Wrong again. On page 7 of the study, under the section Fetal and Neonatal Morbidity and Mortality, second full paragraph, last sentence: “When lethal congenital anomaly-related deaths were excluded (n = 0 intrapartum, n=8 early neonatal, n = 1 late neonatal), the rates of intrapartum death, early neonatal death, and late neonatal death were 1.30 per 1000 (n = 22), 0.41 per 1000 (n = 7), and 0.35 per 1000 (n = 6), respectively (Table 5).”

1.3+ 0.41+ 0.35 = 2.06

Bernstein quoted those exact numbers but never bothered to add them together to get the total.

3. She wrote: “First of all, can I first point out that it’s a 4x increase, not 5.5x (1.6/0.4 = 4).”

Except that the correct number of MANA deaths was 2.06/1000 not 1.6/1000.

4. She wrote: “I seriously have no idea how Dr. Tuteur came up with 5.5x or 450% increase in mortality from the numbers that she cited.”

That says more about Bernstein than about me. I explained how I got it in my post and I just explained it again.

5. Bernstein wrote: “What we’re really looking at here is a risk of death increasing from 0.0004% to 0.0016%. This is a difference of 0.0012 percentage points.”

No, that’s not what we are looking at. Bernstein is off by more than 100 fold. 0.4 deaths/1000 is 0.04%. She added two extra zeros. The homebirth death rate was 2.1/1000, which is 0.21%. So the difference is 0.17%. That sounds like a tiny number, but when you are talking about thousands of births, it’s the difference between 4 deaths for every 10,000 babies born in the hospital and 21 deaths for every 10,000 babies born at home.

6. Bernstein wrote: “All we know about the info Dr. Tuteur got from the CDC website was that it was for white women with low-risk births. This includes hospital births, homebirths, and births in locations other than the home and hospital (though she labeled them as hospital births on the chart she posted).

Clearly she never bothered to look at the CDC Wonder database, which contains an complete description of contents. I specifically noted that I looked at white women, 37+ weeks, 2500 gm babies.

7. Bernstein wrote: “This includes hospital births, homebirths, and births in locations other than the home and hospital (though she labeled them as hospital births on the chart she posted).”

Wrong again! I did not include locations other than home or hospital and label them hospital births. I don’t know where she got that idea.

8. She wrote: “Women who choose to have a homebirth are likely very different from all white women giving birth, so it’s not really a fair comparison.”

Really? White women who give birth in the hospital tend to be younger, poorer, of lower socio-economic class and more likely to smoke than the homebirth group, which means that the 450% higher homebirth death rate actually UNDERCOUNTS the difference in deaths between home and hospital.

Finally, Berstein wrote: “The “homebirths are killing babies” review by Dr. Amy Tuteur was less “focusing on some parts of the study while downplaying others” and more just a sloppy and unscientific attempt at calculating relative risk by using two completely non-comparable data sources in order to scare readers away from homebirths.”

No, what’s sloppy and unscientific is Bernstein’s hatchet job. She is WRONG about the numbers, WRONG about the math, WRONG about the quotes, WRONG about the CDC Wonder database, WRONG about the differences between the home and hospital group and therefore, completely WRONG about her conclusion.

I hope Bernstein and Grounded Parents will acknowledge these errors and correct them. I’d like to see them apologize.

It’s the least they can do after writing and publishing this sloppy hatchet job.