Lori can be developed by showing her internal struggle. Her jealousy could stem from her fear of losing Rick, so exploring her past relationship with Rick and how it contrasts with what she sees between Rick and Michonne can be a start. For example, if she realizes that Rick has changed and she no longer fully understands him because of Michonne, it can lead to growth.
One major challenge is safety. There are zombies everywhere, and finding a place that's completely safe for Lori to give birth and raise the baby is really difficult.