Hello, my friend is pregnant, and her sister in-law recently had a child also. Her sister in-law said she is taking her prenatal vitamins while she is still breast feeding. Jessica(my friend whom is pregnant) also wants to do the same thing, but wants to go on birth control pills also. She is wondering if the prenatal vitamins will interfere with the effectiveness of her birth control pills, and if she should use a back up method of birth control also with it. Please answer, she could use the help! Thanks