sharp shooting pain in low back

Last night I was awoken in the middle of the night by this shooting horribly painful pain in the left side of my low back. It was horrible, I thought I was gonna die. I'm 37 +3 weeks pregnant, first baby here. I woke up every hour for the next few hours with back pain and the desire to pee,  but they weren't as painful as that first one. It didn't happen again l, but now my low back is WAY sore. Is this a sign of labor?