Lactation education

Iodine supplementation during pregnancy and lactation: an important benefit

A new study published in The Nutrition Diary provides further proof that all women who could become pregnant, are pregnant, or are breastfeeding will benefit from a daily multivitamin and mineral supplement.

Iodine is essential for the production of thyroid hormones, necessary for normal growth and brain development in the fetus and infant. Contributing to a limited number of publications on the iodine status of mother-infant dyads, Dr. Jesse Bertinato (Health Canada) and co-authors assessed the iodine status of 132 mother-infant pairs.

The percentages of mothers who used a multivitamin-mineral supplement containing iodine were 90% during pregnancy and 79% and 59% at 1 and 6 months of lactation, respectively. At 1 month, 99% of infants were breastfed, including 70% exclusively breastfed. None of the infants under 12 months old took an iodine supplement. Maternal iodine status was assessed using breast milk iodine concentration. Iodine intakes of infants 1 to 36 months old were estimated from urinary iodine and creatinine (a measure of kidney function and urine dilution) concentrations.

Breast milk iodine concentrations during the first month of lactation indicated adequate maternal iodine status, but these concentrations decreased significantly by the sixth month of lactation. The decline in maternal iodine status coincided with the decline in supplement use. The iodine status of infants was adequate throughout infancy, indicating sufficient iodine intakes from breast milk during the first months of lactation. In older infants, appropriate complementary feeding practices helped meet iodine requirements. Since most pregnant and breastfeeding women do not meet iodine requirements, these results support recommendations that all pregnant and breastfeeding women in North America take a multivitamin and mineral supplement containing iodine.


Jesse Bertinato, Jeremiah Gaudet, Nimal De Silva, Smitarani Mohanty, Cunye Qiao, Matthew Herod, Nathalie Gharibeh, Hope Weiler, Iodine Status of Mother-Infant Dyads from Montreal, Canada: Secondary Analyzes of a Vitamin D Supplementation Trial in Breastfeeded Infants, The Nutrition Diaryvolume 152, issue 6, June 2022, pages 1459–1466,

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