Are prenatal vitamins really necessary or is chewable OK?

I can't swallow large pills, and sometimes crushing or cutting up pills and mixing them in something tastes yucky. I can't imagine doing that for 9 mos! Can I just pop 2 Flintstones a day or is there something about prenatal vitamins that's extra special? I told my gyn I was TTC and she said chewables are fine for now.