Blood Hunters (2016).
I don't think there's anything I can add to this review, which basically matches all your points:
The story begins as a mother and junkie Ellie (Lara Gilchrist) falls to the ground outside in front of her house, seemingly passing out; lay there, alone and falling into the darkness. She awakens to find herself in what she believes to be a hospital room but upon further discovery notices that many things are wrong. Her son is missing. One of the employees is dead on the ground. She is strapped to a bed. The room is empty as well as in a shambles. Oh, and she is now nearly full term pregnant!
With her mind a whirl and her panic towards the pregnancy as well as where he son is, Ellie frees herself and moves out of the room into the corridors looking for anyone and a way out. Ellie discoveries that she is not the only one who has survived what seems to be a massacre in this facility.
Ellie joins her fellow patient Henry (Benjamin Arthur) who cannot remember anything. A computer tech and programmer Marion (Torri Higginson), a male nurse (Mark Taylor), a priest (Julian Richings) and something that lurks in the dark and has been unleashed in the facility to hunt down and kill those who still are alive.
As they make their way through the different dark corners, rooms and tunnels of the building, they must stay in the light as well as find a way out of the building learning what is a resource and who can trust who. As each member begins to come to grips with their lives before the massacre and going forward, influences of religion, logic and instinct collide with survival as we find out what experiments happen and the terrifying results that are created.
Found with the Google query horror movie pregnant creature priest "strapped * bed".
