fetus/infant has a 50% chance of long-term survival outside its mother's womb. With the support of neonatal intensive care units, the limit of viability in the developed world has declined since the 1960s.

As of the mid-2000s, the limit of viability is considered to be around 24 weeks, although the incidence of major disabilities remains high at this point. Neonatologists generally would not provide intensive care at 23