First of all: Congratulations!!!
Second: Make sure your wife, during the whole pregnancy, has:
- plenty of rest
- does not do anything physically or mentally demanding
- does not watch horror movies or other very exciting movies
- keeps stress-levels to an ABSOLUTE minimum
- maintains a good and rhythmically night rest (make sure to get 8 hours sleep/night) and keep sleep intervals the same
- does not drink much alcohol / smoke / use drugs
- keep her (emotionally) happy (believe me: it will affect certain body features, which may be related with childdevelopment)
- eats very healthy (lots of vegetables and fruits), with meat, grain etc. in the right amounts
- does not listen to 'rough' music (heavy metal or anything that has an 'aggressive'-effect)
I say this with a biological/medical education/background. All in all: maintain a healthy lifestyle, with plenty rest, good food (= healthy, vegetables, fruits), keep stress-levels to a minimum and stay emotionally happy.
I say these as pure tips, and i'm not accountable for any posts i put here. For more information on a healthy lifestyle regarding pregnancy, i suggest you to see a professional and read academically approved books on the subject.