You can certainly continue your vegan diet while pregnant.  It is more likely to be hormone and antibiotic free, which is a boon to your baby.  Make sure your diet is also pesticide free and that your vegetables are well washed to prevent listeria and e coli infections.  There are a few things to check:
You can get more than enough protein without eating meat or eggs.  Make sure you gain enough weight to reach the target your doctor sets for you.  If you are very thin and not menstruating regularly, you may need to gain weight to become pregnant. 
Make sure that you follow your doctor’s recommendations for calcium and iron supplementation.  The prenatal vitamins will provide you with some of what you need, but depending on your diet, you may need more.
You need an amount of folic acid that is greater than the adequate amount to achieve optimum protection against birth defects.  Although you are likely eating plenty of folic acid, because it is in leafy vegetables, the evidence is that supplements reduce birth defects even in women with good diets. 
The same is true of choline. You need more than an adequate amount to fully optimize your baby’s brain development and help protect your baby against future mental illness. Phosphatidylcholine and choline are manufactured from soybeans. You would need to seat more than 2 cups of roasted soybeans every day to achieve the optimal levels without also eating eggs or meat, but the soybeans are used to extract phosphatidylcholine and choline for concentrated supplements. Several preparations from Nested Natural and Nutrasal have vegetable-based capsule coatings..

Read more: National Public Radio. Is It Safe To Follow A Vegan Diet During Pregnancy? 2015 link

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