Wednesday, January 10, 2007

Additional data: hospital death rates are lower than claimed by Johnson & Daviss

I have returned repeatedly to the fact that Johnson & Daviss used the wrong comparison (cohort) group in their study in order to make the neonatal mortality rate of 2/1000 look better by comparison. They claim a neonatal death rate of 1.7/1000 for low risk women intending to deliver at home. They removed congenital anomalies from the deaths, but for the purposes of the following comparison, we need to put them back. That's because US statistics for neonatal mortality do not remove congenital anomalies. If you add back the 3 babies who died of congenital anomalies, the neonatal death rate was 2.3/1000 among babies delivered by a CPM in 2000.

Now let's take a look at US Birth Weight/Gestational Age-Specific Neonatal Mortality: 1995–1997 Rates for Whites, Hispanics, and Blacks. This paper breaks down neonatal mortality rates by race, by gestational age and by birth weight. Therefore, we can find out the neonatal mortality rate for white women who delivered a single baby at term. The neonatal mortality rates range from 0.8/1000 at 40-41 weeks up to 1.1/1000 at 42-43 weeks.

So, the neonatal death rate at homebirth in the Johnson and Daviss study was 2.3/1000. The neonatal death rate in this study was less than 1.1/1000. That means that the neonatal death rate in the Johnson and Daviss study was more than double that of white women delivering a single baby at term between 1995-1997.

Keep in mind that the hospital group in this study includes high risk women including those with pre-existing medical conditions, pregnancy complications and babies in the breech or transverse position. The neonatal death rate would be much lower if high risk women were excluded. Moreover, these numbers were from 1995-1997. The comparable numbers from 2000 are almost certainly lower.

So, at a minimum, the neonatal death rate at homebirth in the Johnson and Daviss study was more than double the neonatal death rate in the hospital.

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