There was some research recently demonstrating the link between stress levels during pregnancy and infant behaviour after birth (ie if you experience lots of stress during pregnancy this influences how baby is in terms of laid back or fussy).

I'm a subscriber to the calm mother calm baby theory too, Angus is a relaxed friendly baby and people comment on it all the time. We made a special effort to ensure I wasn't stressed during the pregnancy and we don't overreact to little things and get stressed now either.