Birth plans are a document created to outline the wishes of the birthing person in regards to their care during and after labour. It teaches care providers what kind of birth they would like, things they may be uncomfortable with and desires of how baby will be cared for after delivery. Simple templates can be found here and here.
For survivors of trauma an additional birth plan can be of benefit to help anticipate and find solutions for triggers and anxieties that may come up during labour. Often times the feeling of preparedness is enough to help survivors feel safe an empowered to handle any challenges. This template can be filled out for personal reflection, or shared with care providers and birth support person to help with advocacy during birth. The choice is up to them.