Yes it is safe to use. And you'd have to take A LOT of vitamin A for it to be "bad" for you. Your body readily filters out excess vitamins and minerals. Have u ever noticed the color of your pee when you take a multivitamin? It's bright yellow for that very reason.
I love bio Oil. I'm using it in conjunction with coco butter Vaseline and I'm 36+ and no new stretch marks. I used it with my last pregnancy and he's very healthy.
I've been using Bio Oil religiously since the beginning. I am now 28 weeks. It has on the label for use during pregnancy and I know a lot of friends and family members who have used it during pregnancy with their babies too and they are all happy and healthy.