I think there was a lack of development of her motor skills from her earlier life in a crate. (thedogplace.org)
Once your child becomes responsive to external stimuli (which starts at about 3 weeks old) it's okay to introduce baby play mats to them for faster development of their motor skills. (checkpregnancy.com)
The preschool years are a time of rapid development of motor skills and mental skills. (momvelous.com)