I am currently pregnant and take one or two drops of Lugol's 5% on most days. I also rinse my mouth with Lugols in water and also use it as a scalp rinse prior to washing my hair as it prevents dandruff. I did high dose Iodine prior to pregnancy.
The best info I could find indicated 12.5 mg to be considered safe during pregnancy as long as higher doses were taken prior to pregnancy as you really don't want to start stirring up bromine etc during pregnancy.