I'm pretty sure it would be just fine to use a pregnancy supplmeent while TTC. It would have all the right amounts of Folic Acid, iron , iodine etc and doesnt have Vitamin A. I am using the Blackmores Pregnancy and Breastfeeding one and did so throughout my pregnancy.

Before I beame pregnant, I used a Herron Womens Multi. It has Iron 5mg, Folic Acid 200mcg and a few others but i dont think it has iodine and it doesnt have A.