Advice on preparing for maternity leave?

This week, I began interviewing contractors to cover for me during my maternity leave. I am excited to meet our little one, but am also a bit anxious about stepping away from the workplace for a few months. While I have always performed well (evidenced by year-end performance reviews) and recognize that I cannot legally be let go during leave, I AM worried about being replaced as the go-to person for my projects and that I may be outperformed by the contractor or other colleagues filling in. Are these normal fears? and if so, how do you manage them? Any other advice on how to prepare for leave and return back to the workplace would be appreciated!