This is a great question and one that is very hard to answer. A prenatal vitamin that works for one person may not work for another. I had no issues with the prenatal vitamin provided to me by my doctor when I was pregnant. My daughter, who is 10 weeks along, cannot take prenatal vitamins because they make her sick. She is now taking Flintstones vitamins. It’s best to discuss with your doctor what prenatal vitamins to take until you find one that works for you.