Firsy just be there for your friend and keep her company and talk. Secondly you cant really avoid PND but that does not mean you will get it. However if you do feel down etc speak to someone asap. But please do not panic. We all react different when having a baby and unfortunately some of us are cursed with pnd.
Please tell me how I can avoid getting Postnatal Depression, my friend in such a state just dont want it to happen to me.