The phrase "wriggling baby" refers to a baby who moves and squirms a lot, making small twisting or wriggling movements with their body. Full definition
You have access to your baby from the top instead of having to crouch down to wriggle your baby in. (checkpregnancy.com)
And then I talk about those other days... the ones where you set aside your worries and fears, you curl up with your squishy, wriggling babies while holding hands with the one you love, and you breathe in the moment. (littlemissmomma.com)
Some are more convenient than others with snapping crotch and leg openings making it easier to change the diaper of a sleeping or alternately wriggling baby. (thebabycorner.com)