Here's Matt Stafford's very pregnant wife, Kelly Stafford, gymin' for 2 in Detroit this week -- rippin' off set after set while 38 weeks preggo!!!

Kelly (who's pregnant with baby #3) hit up Elite Training USA and crushed everything from the battle ropes to the weight sled and even some modified deadlifts!!!

Kelly is calling the routine, "Operation GET BABY OUT."

Meanwhile, Matt's working pretty hard too -- gearing up for the NFL season with the Detroit Lions.

Kelly is technically due in 2 weeks -- but she's at full term now and clearly she's ready to celebrate a birthday.