Food poisoning can cause miscarriage. Don't smoke cigarettes. Cigarette smoking has been linked to low weight babies. Don't drink more than 2 cups of coffee. Your baby may be at risk of birth defects.
Caffeine is a drug.
Don't travel the last month of pregnancy. There is always the possibility of premature labor. Don't change the litter box if you have a cat. If your wife needs advice in these areas, gently explain to her that you care about her and the baby and your express your concerns. It is nice to use as a sounding board when you have a concern.