Wednesday, August 15, 2007

Low perinatal mortality correlates with a high C-section rate

Homebirth advocates like to claim that there is no justification for high C-section rates. In particular, they often make two points. The first is the claim that country X has a low neonatal mortality rate AND a low C-section rate. The second is the claim that the World Health Organization recommends a C-section rate of only 15%. So I thought it would be interesting to see what the C-section rates are in countries with low neonatal mortality.

Suprisingly, there has been very little research. I did find a very recent paper in the journal Birth, Cesarean Section Rates and Maternal and Neonatal Mortality in Low-, Medium-, and High-Income Countries: An Ecological Study, claiming to show that there is no relationship between C-section rates and mortality rates in middle and high income countries. Yet that conclusion is belied by the data. Although there is no linear relationship between C-section rates and mortality rates, the data show that virtually every country with low neonatal and maternal mortality rates have high C-section rates. Moreover, most countries with low neonatal and maternal mortality rates have C-section rates ABOVE the 15% level recommended by the World Health Organization. In fact, based on the data, one would have to conclude that there is evidence to suggest that a 15% C-section rate is not high enough.

One of the first things I do when I read a paper is to look for the raw data so I can see if the conclusions are actually justified. I become concerned when the raw data is buried, so you can imagine that my suspicions were aroused by the fact that the raw data is not even published within the paper. It is available only as a separate supplement.

The authors of the paper concluded:
No association between cesarean
section rates and maternal or neonatal mortality was shown in medium- and high-income countries. Thus, it becomes relevant for future good-quality research to assess the effect of the high figures of cesarean section rates on maternal and neonatal morbidity. For low-income countries, and on confirmation by further research, making cesarean section available for high-risk pregnancies could contribute to improve maternal and neonatal outcomes, whereas a system of care with cesarean section rates below 10 percent would be unlikely to cover their needs.
Does the data justify this conclusion? I don't think so.

I downloaded the data and analyzed it a number of different ways. First, I wanted to know the C-section rates for countries with low neonatal and maternal mortality rates. I considered a low neonatal mortality rate to be less than 10/1000 and a low maternal mortality rate to be less than 20/100,000. The authors had looked at 119 countries. Of those countries, only 30 countries met the criteria for low neonatal and maternal mortality. Second, I wanted to see if the countries with low neonatal and maternal mortality complied with the WHO recommendation. Only 10 had C-section rates of 15% or less AND low neonatal and maternal mortality. In other words, of the 30 countries with low neonatal and maternal mortality, fully two thirds had C-sections above the WHO recommendation. The WHO has acknowledged that the 15% recommendation is arbitrary and not based on any data. It seems that the recommended rate is too low.

The bottom line is that low neonatal and maternal mortality rates appear to require C-section rates in the range of 20% or more. Keep in mind that none of these statistics has been adjusted to reflect the risk status of the population. It appears, however, that countries that have low neonatal and maternal mortality AND low C-section rates are countries with homogenous (generally very white) populations that place them at lower risk for complications, neonatal and maternal mortality.

addendum: As I have said before, perinatal mortality is a more sensitive indicator of obstetric care than neonatal mortality because many countries remove certain neonatal deaths by counting them stillbirths even though the babies are born alive. Replacing neonatal mortality with perinatal mortality results in 4 additional countries failing to meet the standard for low perinatal mortality (less than 10/1000). Therefore, there are only 26 countries with low perinatal and maternal mortality. Of these, only 8 have C-section rates of 15% or less. In other words, of the countries with the best perinatal and maternal mortality rates, 70% exceed the WHO recommendations of a 15% C-section rate. Interesting, the country with lowest C-section rate (Croatia) has the highest perinatal mortality, and the country with the highest C-section rate (Italy) has the lowest perinatal mortality.

Here are the C-section rates (1998-2001) for countries with low perinatal and maternal mortality:

Croatia 11.9
Slove 12.6
Czech Republic 12.9
Netherlands 13.6
Norway 13.6
Sweden 14.4
Denmark 15
Israel 15
Finland 15.7
Belgium 15.9
Poland 16.1
France 16.1
Iceland 16.7
United Kingdom 17.0
Ireland 18.6
Austria 18.8
Canada 19.1
Spain 19.6
New Zealand 20.1
Germany 20.8
Hungary 21.1
Australia 21.7
United States 24.4
Portugal 27.5
Italy 31.1

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