In Alberta they don't try to save the baby until 24-25 weeks preg. Why don't they try eariler?

Question

and do they go by the LMP, or by the measurements..(cause you could be really earlier or later)

Answer 1

Most pregnancies aren't considered viable until 24 weeks gestational age. Before that point, the doctors will follow the parents wishes on whether or not to try to save the baby (in the US at least).

They'll probably take both LMP and ultrasound images as well as the baby's size at birth into consideration.