I listed Iodine as one of my pregnancy supplements in my post 'What Supplements I'm taking during my Vegan Pregnancy'. Here's what I said about it: 

Iodine supports your immune system, is important for thyroid health and it also helps maintain strong and healthy nails, skin and hair. More specifically it is critical for brain development. Because babies get iodine from their mothers, pregnant and breastfeeding women need more iodine.

The National Health and Medical Research Council (NHMRC) recommends that pregnant women and breastfeeding women take an iodine supplement containing 150mcg daily. Before I was pregnant my iodine sources were seaweed, dulse, and my fortified homemade almond milk.

With this in mind, I take an iodine supplement almost every day (in pregnancy). If I have my homemade almond milk plus a generous portion of dulse, I tend to avoid overdosing on iodine and skip the iodine that day. When I do take iodine, I have it at night after dinner with a glass of filtered water. Kelp is a really good iodine supplement along with any iodised iodine supplement. I trust Good State and use their products because their products are in a liquid form (replacing big, dry pills). This means the minerals absorb faster and more efficiently than traditional pills. They are also concentrated forms of an ionised mineral! 

More on Iodine: The Iodine IssueThe Science on Iodine