I suspect you're right that you do get better care from hospitals in better neighborhoods and that there are differing expectations, but other factors may have much larger effects that have little or anything to do with social advantage.
From a recent article on infant mortality:
http://www.chicagotribune.com/news/columnists/chi-oped0823ch...
"African-American babies are far more likely to die than white ones, which is often taken as evidence that poverty and lack of health insurance are to blame. That's entirely plausible until you notice another racial/ethnic gap: Hispanics of Mexican or Central or South American ancestry not only do consistently better than blacks on infant mortality, they do better than whites. Social disadvantage doesn't explain very much."
The Latino infant mortality rate differs from the non-Hispanic white one by 0.1 per 1000. This is largely attributed to methodological issues around getting appropriate records and the selection bias of immigration.
From a recent article on infant mortality: http://www.chicagotribune.com/news/columnists/chi-oped0823ch... "African-American babies are far more likely to die than white ones, which is often taken as evidence that poverty and lack of health insurance are to blame. That's entirely plausible until you notice another racial/ethnic gap: Hispanics of Mexican or Central or South American ancestry not only do consistently better than blacks on infant mortality, they do better than whites. Social disadvantage doesn't explain very much."