Final answer:
Mila is achieving motor milestones at a slower pace than typically expected, which would be described as a developmental delay. This term applies to children who reach developmental milestones later than the average age range.
Step-by-step explanation:
Mila is progressing through the expected sequence of motor development, including rolling over, sitting up, pulling up, and beginning to walk at 22 months. However, she is doing so at a slower pace than is typical. Based on the description provided, Mila would likely be described as having a developmental delay. This term is used when children achieve developmental milestones later than the expected average age range.
Since Mila is reaching milestones in the correct sequence, but more slowly, she does not exhibit developmental regression, developmental advancement, or a developmental disorder. Developmental regression would involve losing previously acquired skills, while developmental advancement would mean reaching milestones earlier than average, and a developmental disorder typically involves more pervasive or significant challenges in development.