The New York Times reported a new study that correlated the congnitive brain development of babies and the economic wellbeing of their mothers. Martha J. Farah, a neuroscientist from the University of Pennsylvania who studied the report stated, “It’s proof that just giving the families more money, even a modest amount of more money, leads to better brain development.”
If you've heard any of anecdotal stories about "pandemic babies," children born at the height of the pandemic when their mothers were mostly at home, these children seem to have faster developmental milestones like holding their heads up at just a week old; these community stories are attributed to mothers being able to rest more than normal. So it would be no surprise that if poor mothers do not have the added stress of financial instability, that newborns may have better cognitive outcomes than mothers who are under constant stress.
You can read more about the study here.