Hi,
i'm not sure how much her doc recommends, but I do know it is very important now. This is the most critical stage for brain and neural tube development. I have a friend with a 7 month old and they just found out that he has an encephalocele, which is where his neural tube didn't close all the way and his brain tissue bulges in. This could have been due to lack of folic acid around the 5-6 week of pregnancy or a genetic thing. They just found this out yesterday so they are still running a wazoo of tests and don't know much yet. He does also have cleft pallate and lip as well though, so that could be a sign that it is genetic, but the cleft can be a side effect of the encephalocele as well.
I hope that didn't scare you, as his condition is extremely rare, I just wanted to suggest that right now is the most critical stage for your baby's brain development. If she has been taking the vitamins, i'm sure that's enough of a supplement. However, it probably would help if she could try to eat natural sources of folic acid, even though I know with her schedule it's hard. These things include fruits, green leafy veggies, like spinach, etc..., nuts, and beans. Good luck to you and your girlfriend, i'm sure your baby will be healthy.