If you are using fleece on the back why are you considering adding another layer? I often make quilts for our churches fall blanket drive and use fleece as the basis and add cotton patterned fabric on top of the fleece. If you add another layer you are going to make a very HOT quilt!

Having said all that.... what does "birth" mean in this context. Is it just what I've suggested?

Well no shortages of opinions here. Did you want 10 opinions that liked the same thing?

I would birth it and quilt it. SID or a something easy. But I have never tried to machine quilt with the fleece so not sure how that works.

Pretty quilt some baby will love.

Same here

Well, Quilts For Kids, requests that quilts NOT be tied due to choking hazards - so I wouldn't do that. SID would be fine. Do you have enough of the backing that you could turn it to the front and do a self-bind? Or, as someone else suggested, just find a different fabric that goes well with everything and use that for binding.
Very pretty quilt, BTW. :D

what is birth???

It would look good with an allover meander also.

quilt it and bind it.

please excuse my ignorance, but what is birthing?

When working with a double fleece, I usually turn and top stitch. Your design would lend itself to a near the ditch stitching, with a serpentine stitch down the border. Perhaps dress up the serpentine stitch with a daisy stitch every 10" or so.

Option two is to use wide blanket binding. That, however may distract from the already lovely work of art you've created.

Okay, I'm dumb. What is "birth it or bind it?" I would SID, but don't understand what "birth it" means.