This article is extremely misleading. One of the main causes of infant mortality is parental obesity. [1] As America becomes more and more obese we're going to see more and more of these sort of consequences. For instance our declining life expectancy is also related to this. Diseases ranging from cardiovascular to cancer had been steadily retreating, but as our waist lines expanded the frequency and mortality of these sorts of things have once again begun rising. Better healthcare is not a magic pill for unhealthy lifestyles.
In other words, this is about a healthier people - not about a comparable people with better access to healthcare. I'd expect to see these numbers level out in time. Cubans have also been thickening up as the article does mention, but they're still quite far behind us.
> One of the main causes of infant mortality is parental obesity. [1]
The article you cite does not say that it is a main cause. It says it is a cause, and that it doubles the chance of infant mortality in obese mothers, but it makes no comparisons with other causes.
> In other words, this is about a healthier people - not about a comparable people with better access to healthcare.
We can test your hypothesis. Let's compare two countries that happen to have female populations with the same average BMI, with similar cultures and dominant ethnicity (both former colonies of the British Empire):
* USA -> Female mean BMI: 28.8; Under-five mortality rate: 6.5
* Australia -> Female mean BMI: 28.8; Under-five mortality rate: 3.7
While obesity clearly plays a role in increasing infant mortality, it fails to account for the big discrepancy in infant mortality rates between the USA and the other western nations. One compelling explanation remains: the USA is the only one of these countries without some form of universal healthcare.
You need to compare maternal obesity rates, not mean BMI. The two are not correlated because there are major biases in maternal demographics. For instance in the US most children born are now non-white and there is a strong inverse correlation between income and fertility rates. Both those characteristics (non-white, low income) in turn correlate strongly with increased obesity rates. There are an immense number of studies on this topic. Without link bombing an easy way to find more data is to check out google scholar: https://scholar.google.com/scholar?q=US+infant+mortality+obe...
Something that might help clarify matters most is this [1] paper. It not only gives specific figures but is over an extremely large and comprehensive sample, most of the data is from a ethnically homogeneous sample, and is in a region with nationalized healthcare (Sweden). So it helps remove confounding variables. And there too we find that infant mortality for normal weight women was 2.4/1000 while it was 5.8/1000 for those with obesity grade 3. There was a linear scaling of risks and mortality that mapped directly against obesity. Interestingly enough even being just overweight also corresponded to a slightly increased rate of infant mortality.
Crucially, what obesity tended to lead to was preterm deliveries, congenital birth defects, pregnancy complications, and sudden infant death syndrome. The reason I say crucially is that these [2] are the leading causes of infant death from the CDC. Those issues that arise from obesity are literally the top 4/4 causes of infant death.
In other words, this is about a healthier people - not about a comparable people with better access to healthcare. I'd expect to see these numbers level out in time. Cubans have also been thickening up as the article does mention, but they're still quite far behind us.
[1] - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2674328/