Monday, November 06, 2006

What homebirth studies really show

Many homebirth advocates cite the following studies, because the authors claim that their studies show homebirth to be as safe or safer than hospital birth. It is very important to understand that these studies really show the opposite. Why the discrepancy? The authors are using the wrong control groups.

When making comparisons of homebirth and hospital birth, the hospital group must be as similar as possible to the homebirth group. The appropriate control group for homebirth studies is low risk white women at term. Race is an important factor in neonatal mortality and since over 98% of women who choose homebirth are white, the comparison group must be white also. The control group must resemble the homebirth group in risk factors. So if risk factors like prematurity, pregnancy complications and pre-existing medical conditions are excluded from the homebirth group, they must also be excluded from the comparison group.

Detailed neonatal mortality statistics are available from government bureaus of vital statistics. These neonatal mortality statistics are broken down by race, and often by pregnancy complications as well. Therefore, there is no excuse for not using the appropriate comparison group in a homebirth study; the data already exists.

Let's take a look at the four major North American studies of homebirth to see what the authors claim as compared to what the studies actually show:

study namedeath ratestudy control groupreal control group
The Farm10/100013/1000
(all US births)
Murphy and Fullerton4.1/1000
Johnson & Daviss2/10001.9/1000 (other homebirth studies)1.0/1000
You can see that in every case, the neonatal death rate for low risk white women during the same time period as the study is lower than the neonatal death rate in the homebirth group.

The bottom line is this: It is wrong to cite these studies as showing that homebirth is as safe as hospital birth, because that is not what they show. When the neonatal death rate at homebirth is compared to the neonatal death rate for low risk white women during the same time period, the homebirth group always has an excess rate of preventable neonatal deaths.


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