It should go without saying that all babies have the same nutritional requirements whether they are vegetarian or not. Babies under a year old will need three times as much protein per pound of body weight as do adults. Children over a year and up to the age of twelve will need twice as much.
For babies up to six months old, breast milk will provide enough nutrients, though an iron supplement may be advised at three months. Consult your doctor on this. There will, nevertheless, be some other foods you can introduce at this stage, such as puréed avocado or sweet potato, and up to the time when your baby is weaned. By the age of one, he/she should be on solid foods.