A balanced vegetarian or vegan diet is considered to be a healthy diet, with many health benefits associated with it. Doctors and healthcare practitioners agree that it offers a good grounding for good health and for a very healthy pregnancy. With modern diets, doctors and dieticians tend to focus on cutting out unhealthy food from diets, such as very fatty and processed foods, so vegetarian and vegan diets are a pretty good baseline to start from.
Doctors generally advise the use of supplements from conception right through to postnatal care, such as Iodine, Vitamin B12, Zinc and Folic acid. A good place to start with supplements for a vegan or vegetarian diet during pregnancy would be a good quality source of Omega-3, Vitamins D3, B12 and Iron.