Newborn babies will not be covered under the Child Health Plus program retroactively. Babies will not be covered starting on the first day of the month they were born in, closing the insurance gap that was happening. According to the New York State website:

This bill would allow coverage under Child Health Plus to take effect
retroactively to the first day of the month in which a child is born
who meets the eligibility criteria as determined by an approved
organization or the health insurance exchange marketplace, provided
that the applicant for insurance submits a completed and signed
application and required information and documentation within sixty
days of the child's birth.