As my grandchildren were born in the area, I can say that the problem is not racism.
You see, poverty leads to high infant mortality. Upstream from poverty are: lack of high school education, bearing children before age 20, and bearing children without a husband. So New Jersey is no different than the other 49 states on the poverty side.
However, New Jersey has one of the wealthiest group of persons in any state. All that New York and Philly money likes semi rural NJ and for them the infant mortality is the other extreme, virtually non-existent.
That’s why NJ leads the nation.
Racism as a cause is a smokescreen, to hide the need for personal responsibility.
It is conveniently omitted that educated Americans have been fleeing NJ for decades at this point, and the imported replacements from south of the border are often illiterate IN SPANISH. Now we have our Dem governor-elect pushing to traffic Puerto Ricans here (those impacted by the storm damage there). They are Americans, but they are being trafficked to replace our disappearing middle and upper classes (to keep our government worker caste employed); they certainly won’t turn around any infant mortality problem.
FWIW, this is what most other states can expect - not in 50 years, but in less than a dozen as the impact of years of a negative “white” birthrate is felt.