Last year, I was going to submit mine to an editor that was doing something similar (saw her call for submissions in Poets and Writers magazine). I'm sorry I no longer have her website to give you an idea of what her focus was, but as I recall, she wanted all kinds of birth stories and she asked the authors to give the nitty-gritty details and mince no words when it came to everything. So, my first thought is to decide what your focus is. Would you accept only straightforward non-fiction or could it be creative non-fiction (poetry, etc.)? Would they be unassisted or mw-attended or both?
Besides getting permission in writing from everyone, you'll have to decide how to publish it. If you find a publisher willing, that's great, but with publications such as these (with smaller audiences), you may want to self-publish. That unfortunately means that you will have to front some/most/all of the money and that you will/may have to do all of your own marketing.