1. Overview of 9-month-old baby development standards In the first few years after a baby is born, every month is an important milestone. A 9-month-old baby is already capable of many amazing things. During this period, many parents will begin to pay attention to their child\’s development. Here are some standards a 9-month-old baby should meet. 2. Physical Development Standards 1. Head: A 9-month-old baby should be able to hold its own head completely and turn and lift its head freely. 2. Sitting position: At this time, many babies can already sit up on their own and maintain balance