Is iodine before conception safe during pregnancy?

What does the evidence say about iodine before conception during pregnancy?

1. The body uses iodine to make thyroid hormones, and low iodine levels causing hypothyroidism can impair fertility, raise miscarriage risk, and affect fetal growth and development, though severe deficiency is rare in developed countries. 1
2. The recommended amount of iodine is 220 to 290 micrograms daily during pregnancy, and a prenatal vitamin should contain at least 150 micrograms of iodine, preferably as potassium iodide, since low iodine can also mean poor growth of the baby and a higher chance of preterm delivery. 2
3. The American Thyroid Association recommends that women take a multivitamin with 150 micrograms of iodine as potassium iodide daily starting in the preconception period and continuing through pregnancy and lactation, while cautioning against iodine or kelp supplements above 500 micrograms daily, since some supplements contain up to 100 times the tolerable upper limit. 3
4. Pregnant people need about 250 micrograms of iodine a day, and experts recommend a prenatal vitamin with 150 micrograms of iodine to help meet that amount, while cautioning that too much iodine from supplements such as seaweed can cause thyroid problems. 4
5. Very high iodine levels can cause hyperthyroidism, which may affect both parent and baby and can potentially cause fetal hypothyroidism or a goiter large enough to affect breathing, and while breastfeeding, staying under roughly 500 to 1,100 micrograms a day for extended periods is recommended for this reason. 1

Is iodine before conception safe in each trimester?

• First trimester. Early in preconception planning, this is when starting a prenatal vitamin with iodine matters most, since the thyroid needs a steady supply well before conception, not just after a positive pregnancy test. The American Thyroid Association recommends 150 micrograms of iodine daily from a multivitamin starting at this stage.
• Second trimester. Once iodine intake from a prenatal vitamin and iodine-containing foods like iodized salt, dairy, and fish is established, the routine is mostly about staying consistent rather than adding more. Skip separate high-dose iodine or kelp supplements unless your provider specifically recommends one.
• Third trimester. As you get closer to actively trying, keep the same steady intake going rather than loading up on extra iodine beforehand. Needs step up further once you're pregnant, to 220 to 290 micrograms daily, so this is a good point to confirm your prenatal vitamin's iodine content with your provider.