From the American Academy of Pediatrics;

During pregnancy it is important that you get the appropriate nutrients and energy needed to keep you and your baby healthy. Physical activity is also just as important when you’re pregnant as at any other time of life.

Nutrition

Follow your obstetrician’s advice regarding your use of prenatal vitamins. As mentioned, you should take vitamins only in the doses recommended by your doctor. Perhaps more than any other single vitamin, make sure you have an adequate intake (generally, 400 micrograms a day) of folic acid, a B vitamin that can reduce the risk of certain birth defects, such as spina bifida. Your obstetrician may recommend a daily prenatal vitamin pill, which includes not only folic acid and other vitamins, but also iron, calcium, and other minerals, and the fatty acids docosahexaenoic acid (DHA) and arachidonic acid (ARA). Fatty acids are “good” fats, and DHA in particular accumulates in the brain and eyes of the fetus, especially during the last trimester of pregnancy. These fatty acids are also found in the fat of human breast milk. Make sure your doctor knows about any other supplements you may be taking, including herbal remedies.

Eating for Two

When it comes to your diet, do some planning to ensure that you’re consuming balanced meals. Make sure that they contain protein, carbohydrates, fats, vitamins, and minerals. This is no time for fad or low-calorie dieting. In fact, as a general rule, you need to consume about 300 more calories per day than you did before you became pregnant. You need these extra calories and nutrients so your baby can grow normally.

Exercise

Physical activity is just as important when you’re pregnant as at any other time of life. Discuss a fitness program with your doctor, including fitness DVDs or videotapes that you’ve found of interest. Particularly if you haven’t been exercising regularly, your doctor may suggest a moderate walking or swimming regimen, or perhaps prenatal yoga or Pilates classes. Don’t overdo it. Take it particularly slowly during the first few workouts—even just five to ten minutes a day is beneficial and a good place to start. Drink plenty of water while working out, and avoid activity with jumping or jarring movements.