Because “national guidelines” dictate to the doctors when the baby is viable and they didn’t even look at the baby to determine if he might be able to make it even though he was only 2 days away from the cutoff:

Doctors left a premature baby to die because he was born two days too early, his devastated mother claimed yesterday.
Sarah Capewell begged them to save her tiny son, who was born just 21 weeks and five days into her pregnancy – almost four months early.
They ignored her pleas and allegedly told her they were following national guidelines that babies born before 22 weeks should not be given medical treatment.

This is the type of health care that the left is pushing down our throats. Currently, in America the doctors don’t follow some government guideline to determine care of our premature babies:

She was shocked to discover that another child, born in the U.S. at 21 weeks and six days into her mother’s pregnancy, had survived.
Amillia Taylor was born in Florida in 2006 and celebrated her second birthday last October. She is the youngest premature baby to survive.
Miss Capewell said: ‘I could not believe that one little girl, Amillia Taylor, is perfectly healthy after being born in Florida in 2006 at 21 weeks and six days.

Now the only thing this mom can do is fight to get the guidelines changed.
Go read the rest of the story to see the mindset of the doctors, that’s our future if Obama and the Democrats push through the public option (which we all know is stealth single payer).