What's the right C-section rate? Higher than you think
Anti-cesarean activists love to point out that the World Health Organization has recommended that the C-section rate should be 10-15%. Unfortunately, the WHO appears to have pulled those numbers out of thin air. Its own data shows that a 15% C-section rate does not result in the lowest possible levels of either neonatal mortality or maternal mortality. Indeed, Dr. Marsden Wagner, who has probably done more than anyone to promote the idea of a 15% C-section rate as ideal, is a co-author of a study that actually demonstrates the opposite.
The paper is Rates of caesarean section: analysis of global, regional and
national estimates (Paediatric and Perinatal Epidemiology, 2007; 21:98–113.) The article explicitly acknowledges that the 15% C-section rate recommendation was made without any data to support it. This paper is actually the first paper that attempts to compare international C-section rates with maternal and neonatal mortality.
Since publication of the WHO consensus statement in 1985, debate regarding desirable levels of CS has continued; nevertheless, this paper represents the first attempt to provide a global and regional comparative analysis of national rates of caesarean delivery and their ecological correlation with other indicators of reproductive health.
The data regarding C-section rates below 10% is stark:
...[T]he majority of countries with high mortality rates have CS rates well below the recommended range of 10–15%, and in these countries there appears to be a strong ecological association between increasing CS rates and decreasing mortality.
How about the data on C-section rates above 15%? The authors claim:
Interpretation of the relationship between CS rates and mortality in countries with low mortality rates is more ambiguous; nevertheless, the sum total of the evidence presented here supports the hypothesis that, as has been argued previously, when CS rates rise substantially above 15%, risks to reproductive health outcomes may begin to outweigh benefits.
Not exactly. Indeed, not even close. The data show that low maternal mortality and low neonatal mortality are associated almost exclusively with high and very high C-section rates.
The article contains a variety of charts that make this clear. Of note, the charts are of an unusual kind. Rather than graphing C-section rates against mortality rates, the authors chose to graph the log (logarithm) of C-section rates against the log of mortality rates. A log-log graph has the advantage of exposing tiny differences when all the values are bunched close together, but all the values are not bunched together in this situation. C-section rates occur along a broad range, and mortality rates occur along a broad range. As a consequence, the log-log graph magnifies the effect of tiny differences and minimizes the effect of large differences. Therefore, you need to be very careful in interpreting the graphs.
This is an adaptation of the chart that appears in the paper comparing C-section rate to maternal mortality (the authors claim that graphing C-section rate against neonatal mortality produces a similar result). The area representing a C-section rate of 10-15% has been highlighted in yellow. The horizontal blue line represents a mortality rate of 15%. Lower mortality rates are below the blue line and higher mortality rates are above the blue line.
The data themselves are quite clear. There are only 2 countries in the world that have C-section rates of less than 15% AND low rates of maternal and neonatal mortality. Those countries are Croatia (14%) and Kuwait (12%). Neither country is noted for the accuracy of its health statistics. In contrast, EVERY other country in the world with a C-section rate of less than 15% has higher than acceptable levels of maternal and neonatal mortality. There nothing ambiguous about that.
The authors claim:
Although below 15% higher CS rates are unambiguously
correlated with lower maternal mortality; above this range, higher CS rates are predominantly correlated with higher maternal mortality.
No, that's not what it shows at all. It shows that only countries with high C-section rates have low levels of maternal and neonatal mortality. A high C-section rate does not guarantee low maternal and neonatal mortality because C-section rate is not the only factor. For example, Latin America (represented on the chart by open diamonds) has a high rate of C-sections performed for social reasons, but does not have a low level of maternal mortality.
The bottom line is this: The only countries with low rates of maternal and neonatal mortality have HIGH C-section rates (except Croatia and Kuwait). The average C-section rate for countries with low maternal and neonatal mortality is 22%, although rates as high as 36% are consistent with low rates of maternal and neonatal mortality.
The authors claims are not supported by their own data. There is simply no support for a C-section rate of 15%, since virtually none of the countries with low rates of maternal and neonatal mortality have a C-section rate of 15% or below, and most have rates that are far higher. There is also no support for the claim that "the sum total of the evidence presented here supports the hypothesis that ... when CS rates rise substantially above 15%, risks to reproductive health outcomes may begin to outweigh benefits". When C-sections are performed for medical indications, there is no evidence that rising C-section rates lead to rising rates of maternal or neonatal mortality.
The authors own data indicate that a C-section rate of 15% is unacceptably low, and that the average should be at least 22%, with rates as high as 36% yielding low levels of maternal and neonatal mortality.
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Comments
Sometimes people forget the desired outcome is a healthy child and mother, and everything else is gravy. I wish this data had been around when I had my C-sections and had to deal with the guilt-mongers.
"I wish this data had been around when I had my C-sections and had to deal with the guilt-mongers."
What's especially distressing is that people have been using the WHO 15% to complain about the C-section rate without understanding that they WHO simply made it up.
One thing I learned over the years talking with many moms and many doctors, every birth is unique.
I understand that a breeched baby for a first time delivery is considered risky and a C-section is recommended. But breeched babies are rare. What are the other causes?
"I was diagnosed with preeclampsia at a regular check-up ten days before my due date."
Many people don't realize the role that C-section has played in dramatically lowering both neonatal and maternal mortality. The only cure for pre-eclampsia, and the only way to prevent it from progressing to full blown eclampsia and seizures is to deliver the baby. Sometimes that can be accomplished by vaginal delivery; sometimes it takes a C-section.
It's not a coincidence that the only countries with low rates of neonatal and maternal mortality have high C-section rates.
"What are the other causes?"
Reasons for C-section include fetal distress (abnormal fetal heart rate), a baby that is stuck (cephalo-pelvic disproportion), placenta covering the cervix (placenta previa), premature separation of the placenta (abruption), breech and other abnormal positions, some cases of twins, and repeat C-sections.
In Japan, of course, a number of risk factors (obesity, socioeconomic disparities, lack of access to health care throughout life) are not present as they are in the United States. They are also much more strict about weight gain during pregnancy, and have a strong commitment to minimum intervention during childbirth. Mind you, from an American perspective, the weight gain obsession can border on the ridiculous (I gained 27 pounds to have an 8#10oz baby, but there was no way I was going to keep my weight gain to 9 kg or about 20 pounds!) and the lack of pain control options also reflects a zero-choice atmosphere for the women. But the health outcomes are great.
That is, the chart shows only a strong *correlation* between low c-section rates and high maternal mortality. It shows a very mixed picture for those countries with high c-section rates; some have low maternal mortality, while it's strikingly high in others. As you note, a high c-section rate does not in itself guarantee low maternal mortality because other factors are also in play.
I'd want to know if anyone has studied the effects of these possible confounders. For instance, there's good reason to think that low risk tolerance drives a high c-section rate. That's something you find in countries like the U.S. - not so much in poor countries where people feel unable to influence fate. The legal system contributes, too - and since poor countries are unlikely to have court systems that award large monetary damages for birth injuries, they're unlikely to have high c-section rates for that reason, too. Then there's the general effects of nutrition, sanitation, availability of trained birth attendants, availability of blood transfusions and antibiotics, access to prenatal care - all factors that will affect maternal mortality, and all factors that correlate with general prosperity levels, as does MM.
In sum, you raise some good and important questions, but the data are not adequate to suggest causation, only correlation.
"What about the CS rate in Japan? I gave birth there, and my understanding at the time was that the CS rate was less than 10% and the maternal and neonatal mortality were the lowest in the world."
The most recent figures I could find were from 2005 and showed that Japan had a C-section rate of 21.4%.
As I said in my post, with the exception of Croatia and Kuwait, there are NO countries that have low rates of neonatal and maternal mortality AND have C-section rates of 15% or below. That's why it is so disingenuous for the WHO to keep quoting a rate that it made up, and that appears to be incompatible with low rates of neonatal and maternal mortality.
Japan does have a lower rate of perinatal mortality than the US, but that is for the reasons that you mentioned, which lead to a lower risk profile of the Japanese population. In addition, race is unfortunately a risk factor for perinatal death. Women of African descent have higher rates of perinatal mortality regardless of where they live in the world. It is not a coincidence that Japan has virtually no women of African descent among the population and the US has the highest proportion of women of African descent in the industrialized world.
"In sum, you raise some good and important questions, but the data are not adequate to suggest causation, only correlation."
You are correct, but I would note several important points:
1. The WHO has acknowledged that it made up the "ideal" C-section rate of 10-15%.
2. This study, published within the past year, is the first study that actually compares international C-section rates with outcomes.
3.With the exception of Croatia and Kuwait (and I take leave to doubt the validity of those statistics), there is NO country that has a C-section rate of 15% or below and also has low rates of neonatal and maternal mortality.
4. Judging by the information in this paper, a minimum C-section rate of 20% or more is probably necessary to guarantee low neonatal and maternal mortality.
Try these figures:
Country CS(%) neonatal deaths/1000 maternal deaths/100,000
Holland: 13.6 3 16
Norway: 13.6 2 16
Sweden: 14.4 2 2
Denmark: 15.0 3 5
Israel: 15.0 3 17
Finland: 15.7 2 6
US: 24.4 4 17
The trouble is that many of the countries with really low section rates also have very high rates of illiteracy - and very sub-optimal proportion of skilled assistance accessible during birthing.
(See Althabe et al, Birth: 33(4),270-7, 2006.)
The most accurate measure of obstetric care is perinatal mortality death from 28 weeks of pregnancy to 28 days of life). The reason that it is more accurate is because many countries play fast and loose with neonatal mortality statistics by counting premature babies as stillbirths, even when they are born alive, instead of counting them as neonatal deaths. The World Health Organization recommends the use of perinatal mortality to get around these statistical tricks and the US follows the WHO definition.
According to the WHO 2006 report on perinatal mortality, the US has one of the lowest rates in the world, lower than Denmark, the UK and the Netherlands. This is all the more impressive when you consider that the US has a much higher risk population than those countries.
By the way, the journal Birth, which you cited, is not an unbiased, scientific journal. It publishes articles that support unmedicated childbirth, and a lower C-section rate whether the articles are scientifically accurate or not.
In addition, be wary of any "statistics" quoted by anti-Cesarean activists to condemn American obstetrics. Most of them, like the neonatal mortality rates you quoted, are knowingly and deliberately, the wrong statistics to use in international comparisons.
http://www.who.int/making_pregnancy_safer/publications/neonatal.pdf
"Where is you get the 21.4% figure from, for future reference?"
I found it in an International Herald Tribune article on the rising C-section rates in Asia:
http://www.iht.com/articles/2007/05/09/news/birth.php?page=2