I am 21 weeks pregnant and JUST noticed the warning label on my levothyroxine bottle that states "avoid calcium and iron supplements for 4 hours"... obviously my prenatal vitamin has these among other ingredients. I have been taking them together every morning since the beginning of my pregnancy. About a week ago (after I read the label) I started waiting 4 hours to take my prenatal vitamin. I am now concerned about the increase of absorption of the levothyroxine as I read when taken with other supplements is decreased by 1/3.