I hope you avoid it, @holb54. You sound like you know what to look out for in yourself. I'm not sure what I had was PND - at the time I would have said I was fine but I was irritable, angry, exhausted, had low mood... In hindsight that's probably a touch of PND, isn't it? I was really traumatised by my son's early arrival and felt really overwhelmingly guilty about it. I used to Google all the time "am I depressed or just sleep deprived?" without realising that the two aren't mutually exclusive. For me I think my low mood was caused by the loss of routine, identity and lack of sleep. It took me a short while to make friends on mat leave and build up a network of classes/groups to go to but things definitely improved when I had a routine and friends. Unfortunately I'm one of those people who lack of sleep has a really significant impact on how I'm feeling and I also think too much of my identity was wrapped up with my work.
This time around I feel more balanced and I'm going to let DH do more, make time to sleep and rest, try to plan a flexible routine in advance, possibly do NCT again (I didn't click with my first group, which was a big disappointment at the time - nice people but nothing but babies in common and that wasn't really enough), try to exercise more, be kinder to myself! Also my lovely friend is due a month before me and she will be someone I can share the ups and downs with.
Great idea about accessing family support too - DS was fantastically badly timed, arriving about a week after my nephew was born, so there wasn't really anyone there to help. My MIL was great while I was in hospital but she left before I got home to give us space as a new family unit.
Basically, I'm pretty petrified about the baby days again but I've survived it once and can do it again! Also I cannot tell you how much of a joy and blessing my son is and how much I love him. Just looking forward to getting to that point again with this one! I am happy to say now I didn't get that immediate rush of love for him when he was born and it took a while for that to come but I just couldn't imagine life without him now.