Generally speaking the folks here are right, you should be able to maintain veganism unless things go really sideways. I’d recommend getting in touch with a dietician though if you’re really worried (not a nutritionist, different beast) and having them go over your plans. Iron deficiency is a particular risk, one that can be easily surmounted as long as you’re aware of it… Way harder to keep iron up when pregnant even than usual, and it’s already tough as we all know.