I'm afraid (or should that be glad!) that I have no personal experience of post natal psychosis but I am shocked that the review couldn't find any research into the treatments available to mothers and their families in need of intervention, despite recent high profile cases.
As with so many areas of treatment for mental illness, outcomes are determined by the luck of the draw .... by the chance of being spotted by the right person at the right time. Training midwives and GPs to become that right person must surely be a good start. Giving them the time and knowledge to provide appropriate interventions (drugs, family support and talking therapies) is the obvious follow-up.