Natural vs. "Synthetic" PreNatal Vitamins?

Taylor • Herbal Tea Sipping Yogi: Living at 7,000ft in elevation among the pines. Married. Mama. Artist. Happy.
Any opinions or thoughts on Natural, Organic Prenatal Vitamins verses the more "Synthetic" Options?? 
Such as New Chapter or Graden of Life vs. One-A-Day or Nature's Bounty?? 
The Natural, Organic Vitamins are more expensive but is it worth it? 
Don't we just pee out any nutrients our bodies don't use?
Help!! :)