Posted by: notdeaddinosaur | November 5, 2009

Tweaking the Tail of the Home Birth Tiger

Science Blogs has a new contributor: Dr. Amy Tuteur, an OBGYN who elicits, shall we say, very strong reactions among her readers.

Dr. Amy’s debut post trumpets “The Tragic Toll of Home Birth!” (The exclamation point isn’t actually there, but doesn’t it sound like it should be?) Reading through it, though, sounds more like a screed against midwives — specifically those who are not CNMs (Certified Nurse Midwives) — than home birth per se. She includes this nifty chart to demonstrate her point:

Let’s see. According to these numbers, non-CNMs do indeed have higher neonatal mortality rates than either MDs or CMNs, however MDs have nearly double the mortality rate of CNMs! Wow. If I really want to be safe, I should go to a midwife.

Then again, that table doesn’t actually say anything about home birth. It just breaks down mortality figures by birth attendant. As it happens, the database Dr. Amy links is ridiculously easy to navigate. (Go and play with it.) In fact, I was able to come up with this breakdown of home birth vs. hospital birth, by birth attendant, using the same remaining parameters as Dr. Amy (2003-2004; white women, 37+ weeks, ages 20-45):

[Sorry I can’t manage it in a nifty table format]

In Hospital:
CNM: Deaths: 107, Births: 292,422, Deaths/1,000 births: 0.37
MDs: Deaths: 2,118, Births: 3,498,447, Deaths/1,000 births: 0.61
Other Midwives: Deaths: 2, Births: 4,323, Deaths/1,000 births: Suppressed

Not in Hospital:
CNM: Deaths: 6, Births: 11,853, Deaths/1,000 births: Suppressed
MD: Deaths: 7, Births: 2.689, Deaths/1,000 births: Suppressed
Other Midwives: Deaths: 20, Births: 16,613, Deaths/1,000 births: 1.20

(Note: Rates are suppressed when the numerator is less than 20, because the figure does not meet the NCHS standard of reliability or precision.)

Source: United States Department of Health and Human Services (US DHHS), Centers of Disease Control and Prevention (CDC), National Center for Health Statistics (NCHS), Office of Analysis and Epidemiology (OAE), Division of Vital Statistics (DVS), Linked Birth / Infant Death Records 2003-2005 on CDC WONDER On-line Database. Accessed at http://wonder.cdc.gov/lbd-current.html on Nov 5, 2009 11:45:58 AM

So what does this really mean? It means that a total of 33 babies who were born at home between 2003 and 2004 died in their first month of life. Yes, more of them had mothers who were attended by non-certified midwife than by a CNM or MD. By contrast, if you add them up, there were 2,227 babies born in hospitals who didn’t make it past a month either. The rates for total mortality by place of birth including all birth attendants is 0.59 per thousand births for hospitals and 1.06 for “not in hospital”.

Okay, then. Say we admit that, taking all comers, a baby is about twice as likely to die if born at home than in a hospital, or even three times as likely if attended by a lay midwife. Sounds pretty scary, no? Well, no.

It’s the age old difference between absolute and relative risk. Take TBTAM’s trick of using a piece of graph paper with 1,000 squares, and see what the difference is between having one square colored in, or two (or even three). Combine that with the tiny absolute numbers of women who want to give birth at home in the first place (I didn’t want to have to clean up after it, frankly) and the whole thing starts looking more like the ideological witch hunt against midwifery that it actually is, and a whole lot less like a noble call to save large numbers of innocent babies from their mothers’ intransigence.

News flash: people choose home birth over a hospital experience for many reasons, and will continue to do so even in the light of these statistics. Why? For the same reason they ride motorcycles, some of them without helmets. They feel that the advantages to them outweigh the risks. How can they best minimize the risk? By selecting a birth attendant with appropriate training and experience, for one. More training for midwives? I’m all in favor. But demonizing the entire home birth community by condemning their “Tragic Toll” is uncalled-for.

If you want to talk about “Tragic Tolls”, Dr. Amy, check this out:

The National Child Abuse and Neglect Data System (NCANDS) reported an estimated 1,760 child fatalities in 2007.

Now that’s tragic.

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