I truly don't know. But why would poverty be insufficient to account for it? If you lack access to medical care facilities, it's a whole different world. "Third-world" nations at least have a history of midwives and such, but in the USA if the "expectation" was to go to the hospital, but then you don't actually go, the facilities that are available can be lesser. There is also a segment of society where rich women choose to use midwives rather than go to care facilities, and I wonder how much that plays a role as well (in terms of infant deaths not due to poverty, but bc of misinformation).

https://www.cdc.gov/reproductivehealth/maternalinfanthealth/infantmortality.htm - admittedly I am no expert at reading this, but it looks like poverty at first glance. Moreover, it looks like if not all the right-wing-controlled areas, at least the ones that are the most racist - looking at the race distribution table it is, how shall we say, not white people even in those areas. Almost like "those people" (non-white) are allowed to pay taxes, but when it comes time to apportion the spending priorities, the white people in charge choose to spend elsewhere, every time. Access to food, ability to get away from toxins, as well as pregnancy-specific concerns.

Interestingly (to me), the causes of infant deaths in America seem very different (again to my unpracticed eye) than those worldwide: https://www.nichd.nih.gov/health/topics/infant-mortality/topicinfo/causes.

But I could be biased, after having watched this: https://youtu.be/-v0XiUQlRLw?si=3CruIh83bPWX6dKA. That's probably a good thing, since we should be biased towards facts:-). I hope that video helps explain my contention that there is not just one single "American experience", and rather there is kind of a second experience altogether depending on skin color and location. And the latter overlaps nontrivially with "third-world" nations, despite being amidst the land of plenty.

Part of what made America a beacon of hope for the world was how while it had its top people and the people mashed down at the bottom, same as everywhere, most of the people were somewhere in the middle. Whereas now, the bottom isn't so much getting any lower (if anything it should mainly rise as medical stuff becomes even cheaper over time?) but the average is dropping, fast, to get closer to joining it.:-| Though ofc it still has a long way to go, and things may always change in the meantime (even if that looks doubtful right now).