I agree. After reading all about Marie Osmond's battle with mental problems after the birth of her last child... she finally learned it's not something that can be cured with psychotic drugs. It's an endocrine/hormonal-thing. Too mad GYN/OB's don't get more education in hormonal abnormalities and deal with it during pregnancy. We'd see fewer of the these cases.
There was a good interview on KOB (Albuquerque radio station) right after the Andrea Yates story broke. An OBGYN nurse described here experience with post-partum depression. She said she had feelings like here child was possessed by Satan among others. However, she recognized the symptoms and immediately got help. One point she made was that estrogen levels drop by about a factor of 100. It's a real shock to the body.
I'm not sure this applies to the arm-severing case.