My mother says that babies are more resilient to stress than we think. And stressing about it more wont help so just try to be relaxed as much as possible. I went through a lot of stress before I even found out I was pregnant and look back and am so grateful nothing bad happened.
I was so highly strung and stressed with my first I was worried about that too. I didn't go into labour infill 39 weeks though and baby was such a chilled relaxed little dude. (: