‘I Didn’t Know About Iodine:’ Secrets of this Essential Supplement during Pregnancy
By Kiran Thanigasalam, BPharm, MPH, MotherSafe (MotherToBaby’s Australian partner)
As Birth Defects Prevention Month came to a close last month, I thought it was crucial I keep the momentum going by talking about Iodine with every patient I come across as a pharmacist and counselor. Why? When planning for baby, you and your prenatal vitamin need to be on the same team when it comes to health. While there may be no "i" in team, there is an "i" in both iodine and iron. When the topic of iodine supplementation is raised with pregnant women, I can tell you that a lot of women confuse iodine with iron when searching for the perfect prenatal vitamin.
What is iodine?
Iodine is a naturally-occurring trace element which is vital for thyroid function. It is an essential component of the thyroid hormones T4 and T3. Some common food sources include seaweed, fish, egg and iodized salt.
The total recommended daily intake in pregnancy ranges from 220 micrograms (U.S. RDA) to 250 micrograms (W.H.O, Unicef, ICCIDD). While many women report that they have "tested within normal limits for everything" and have a balanced diet, the American Thyroid Association, American Academy of Pediatrics and the Endocrine Society recommend a prenatal supplement of at least 150 micrograms of elemental iodine per day for every pregnant woman. This recommendation assumes that the woman is also getting 70-100 micrograms of iodine in her daily diet.
The only exceptions to this recommendation are women with pre-existing thyroid conditions such as Graves' disease who have been advised by their treating specialists to avoid iodine supplements.
Dietary iodine intake in the US has generally been considered adequate since the fortification of table salt and other foods. However, since routinely testing iodine concentrations in urine is not practical and since supplementation is cheap, safe and effective, the preventative approach of a one-size-fits-all supplement in pregnancy provides peace of mind - especially for at-risk groups like vegetarians or those who do not consume dairy products or iodized salt.
Getting enough iodine is crucial for a developing baby’s brain and skeleton.
In its most extreme form, iodine deficiency can result in maternal goiter (a condition in which the thyroid gland becomes enlarged), miscarriage and stillbirth. However an underactive thyroid gland in the mother, even if she is not having any symptoms, can cause the baby to have neurodevelopmental problems such as a reduced IQ.
Clearly, not all prenatal vitamins are the same.
A 2009 paper published in the New England Journal of Medicine surveyed 223 prenatal multivitamins marketed in the United States and found that only 51% contained iodine, and 37% of those products contained kelp as the iodine source. Unfortunately, wide variations in the iodine content of kelp make this an unreliable choice of supplement. Potassium iodide is preferred.
As a result, it is crucial to check that the prenatal vitamin you are contemplating buying contains not only folic acid (which is important to prevent birth defects of the spine, called neural tube defects), but also iodine at the recommended amount and in the right form. Here’s to a winning team when it comes to iodine and health for you and baby!
About the Author
Kiran Thanigasalam, BPharm MPH, is a pharmacist and teratogen information specialist at MotherToBaby’s international affiliate, MotherSafe, which is based at the Royal Hospital for Women, Randwick in Australia.
MotherToBaby is a service of the international Organization of Teratology Information Specialists (OTIS), a suggested resource by many agencies including the Centers for Disease Control and Prevention (CDC). If you have questions about alcohol, medications, vaccines, diseases, or other exposures, call MotherToBaby toll-FREE at 866-626-6847 or try out MotherToBaby’s new text counseling service by texting questions to (855) 999-3525. You can also visit MotherToBaby.org to browse a library of fact sheets.
The Teratology Society partners with the OTIS MotherToBaby through joint sessions at our annual meetings as well as a shared interest in public health issues for expectant mothers.
For more information on iodine and its important role during pregnancy, please see the Teratology Society's Iodine Deficiency in Pregnancy position paper that was published in our journal Birth Defects Research.