I'm 38 weeks pregnant, what are these rhythmic movements?

I know what my babies hiccups feel like, they're a little more "jerky" and quick than these. I almost feel like it's a steady breathing motion. Is it possible that I'm feeling him practicing breathing? He's already head down and engaged, so his bottom is up and I seem to feel them more towards the lower half of his body. Has anyone else experienced this or know what it could be? Any ideas would help!