Walking Through Postpartum Depression is written by Judy Dippel and I recommend it. It is both an instructional workbook and a write-in Bible study and self-examination to help a new mom deal with feelings of lostness, lack of identity, loss of hope, and a lack of trust in her own mothering instincts.
But this is a positive workbook that will help many. If you know of anyone who is struggling after childbirth, I know it will help.