Postpartum depression

Can you avoid postpartum depression? I had it with my first baby and it got really bad. Well I'm pregnant with #2 and scared I'm going to get it again. I really want to breastfeed this time because I couldn't the first time and I have a 2 year old to take care of also and I don't think I'll be able to take care of two kids with postpartum depression. 
Thanks