Well, start with a strong plot. It could be something like the character finding out she's pregnant just as she's about to go on a big school trip. This creates immediate tension. Develop the character's journey through the pregnancy step by step. Include details like her first doctor's visit, how she tells her parents, and how she copes with morning sickness. Use dialogue that is true to the characters in girl meets world. Let their voices shine through as they deal with this life - changing situation.
First, do your research on pregnancy. Understand the physical and emotional changes that come with it. For girl meets world, make sure the characters stay in - character. If Riley is the pregnant character, for instance, keep her optimistic and kind - hearted nature. Also, create conflict. Maybe her family has different ideas about what she should do with the pregnancy.