I am going to guess that this was produced in the 1960s.
This has been worn and washed.
Cotton flannel, yellow, with screenprinted Tweety design.
Blue vinyl binding is stitched around the wrists and ankles, and the neckline is bound in a blue flannel.
Elastic in wrists and ankles, still stretches just fine.
In the photos, the yellow shows differently in several photos. It is a butter yellow.
This looks like it was made as a costume, but may have been sleepwear.
I cannot find any labels.
Please ask questions!
Measurements: Neckline to crotch length 18"
Length from top of shoulder to bottom ankle 30"
14.5" chest/body circumference
Probably a size 2-3.