Protein: During pregnancy, your body requires a little bit more protein. Most vegetarian diets are protein rich, so this should not be a huge concern. Protein rich food include legumes, (like green peas, soybeans, chickpeas, black, navy, kidney and pinto beans, as well as peanuts), Whole grains (brown rice, whole-grain cereals, barley, quinoa, couscous, whole-grain breads) and Soy (soybean, tempeh, tofu). However, vegetarians must take extra care to ensure adequate iron and calcium in their diets.
Iron: Vegetable sources of iron (beans, soy products, barley, pumpkin seeds, dried fruits, spinach, seaweed) are not as well absorbed by the body as iron found in meat. Consider taking an iron supplement and iron fortified cereals to avoid this problem. When eating iron rich food, do pair it up with a glass or orange juice or any other drink rich in Vitamin C, as it assists in digesting iron.
Calcium: Try to have at least 3 servings per day. Good sources of calcium include milk, cheese and yoghurt. If you're not a member of the milk-mustache club, you'll have to depend on non dairy sources of calcium like dark green vegetables, sesame seeds and fortified soya products like tempeh.
Vitamin D: The best dietary source of vitamin D is milk. Alternatively stand in the sun for a few minutes each day. The sun helps your body produce vitamin D. Many breads and cereals are also fortified with vitamin D, so add those to your diet as well.
If you are looking for more information on vegetarian diets during pregnancy, do check out these links