What is the term that thomas and chess used to describe babies who have a positive disposition, whose body functions operate regularly, and who are adaptable?

Easy babies. Thomas and Chess's temperament types for babies fall into one of 3 categories. Easy babies represent 40% of all infants and are able to adjust easily to new situations, are generally cheerful and easy to calm, and quickly establish routines. The other two would be difficult babies and slow-to-warm-up babies, which represent only 10 and 15% of infants respectively.