The Underrated Problem of Iodine Deficiency in Pregnancy
And the problems with excess iodine
Iodine is an essential trace mineral that is needed by the body for the production of thyroid hormones triiodothyronine (T3) and thyroxine (T4).
These hormones play a crucial role in regulating metabolism, growth, development, and many other body processes.
Iodine is absorbed from the diet and transported to the thyroid gland, which concentrates it to produce T3 and T4.
Without adequate iodine intake, the thyroid is unable to make enough thyroid hormones to meet the body’s needs.
This is especially important during the most vulnerable time in a human's life.
Iodine Requirements Increase During Pregnancy
Iodine requirements increase significantly during pregnancy because the developing fetus relies completely on maternal thyroid hormones early in gestation before its own thyroid function develops.
Thyroid hormones are especially critical in neurological development during the first trimester, as they regulate gene expression in the fetal brain.
Later in pregnancy, the fetus starts producing its own thyroid hormones using iodine obtained from the mother.
The increased demand can lead to maternal iodine deficiency if dietary intake is not sufficient.
The World Health Organization recommends 250 mcg of iodine intake daily during pregnancy, higher than the 150 mcg recommended for non-pregnant adults.
Consequences of Iodine Deficiency in Pregnancy
Even mild iodine deficiency during pregnancy has been associated with serious adverse effects on the neurodevelopment of the fetus.
Impaired cognitive function and motor skills, reduced information processing abilities, and cretinism are observed in the offspring of iodine-deficient mothers.
One study found children born to women with mild-to-moderate iodine deficiency had IQ scores an average of 10–15 points lower than those whose mothers had adequate iodine intake.
The neurodevelopmental impacts often persist into adolescence and adulthood.
Iodine deficiency can also lead to goiter in the mother as well as miscarriage, preterm birth, stillbirth, and congenital abnormalities in extreme cases.
Optimizing iodine status before and during pregnancy helps prevent these complications.
Global Iodine Deficiency Is a Concern
Insufficient iodine intake continues to be a public health issue globally, despite efforts to increase iodine status through fortification programs and supplements.
According to the WHO, iodine deficiency is still prevalent in South and Southeast Asia, Africa, and Eastern Mediterranean regions.
29.8% of school-age children worldwide are estimated to have insufficient iodine intake.
Pregnant women are also vulnerable, with 15–35% estimated to have inadequate iodine levels and over 50% in some developing countries.
Dietary Sources of Iodine
The issue with iodine is its natural occurrence in food sources.
Many of them, we don’t eat frequently, are told not to eat, or simply don’t like (anymore).
The best dietary sources of iodine include seafood, seaweed, eggs, dairy products, and iodized salt which was created to counter the growing iodine deficiency decades ago.
However, amounts can vary greatly depending on environmental factors.
For example, iodine levels in fish depend on the iodine content of their habitat. Which is getting worse every day.
Plant-based sources are sometimes unreliable, as iodine content depends on soil concentrations. Also getting worse by the day.
With shifting dietary patterns away from iodine-rich foods, polluted oceans, and depleted soil, deficiencies are increasing in developed nations as well.
Iodine Supplements During Pregnancy
To help meet increased iodine needs, supplements are recommended prior to conception and during pregnancy and lactation.
Supplements with 150–250 mcg formulas are generally considered safe.
However, amounts exceeding 500 mcg per day should be avoided except under medical supervision due to thyroid toxicity risks.
Monitoring iodine status during pregnancy through urine testing helps ensure appropriate supplementation.
The Bottom Line
Adequate iodine intake is especially crucial during pregnancy for fetal brain development.
Meeting the increased dietary requirements can be challenging without access to certain foods or supplementation.
Ensuring pregnant women have sufficient iodine intake through diet and supplements is key to preventing permanent neurocognitive disabilities in children.
More awareness of iodine’s importance is needed among women planning pregnancy.
Iodine is not a deficiency of the past. Not anymore.
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