Data is not consistently collected at medical centres and follow-up research is limited. But generally, experts know that most micro-prems will suffer some chronic physical difficulty. There is no easy answer. For starters, the law is ambiguous. But doctors are not legally obliged to keep such highly premature babies alive.
Some hospitals have guidelines, yet they're just that-guidelines.
So ultimately each doctor must decide whether or not to intervene, or resuscitate, an infant knowing that a micro-prem will die without intensive care. Then it would be totally wrong and unethical to subject that baby and the family to intensive care. It would be quite cruel. It would be futile. If we take a 21 week gestation, a little bit longer I think the same applies.