The fire broke out around midnight on the 1100 block of Mechanic Street.
Police say the homeless couple were allowed to use the house but there was no working heat or electricity.
The blaze was showing on the second floor where the man and woman jumped from a window.
They landed on an awning then hit the sidewalk.
Both victims were taken to the hospital.
The man fell on his face and was critically injured.
The pregnant woman is in stable condition.
So far, there is no word on what sparked the blaze.
