Prenatal and Postpartum Maternal Iodide Intake from Diet and Supplements, Urinary Iodine and Thyroid Hormone Concentrations in a Region of the United Kingdom with Mild-to-Moderate Iodine Deficiency

Abstract

Iodine is essential for normal thyroid function, supporting healthy fetal and child development. Iodine requirements increase in pregnancy, but many women in regions without salt iodization have insufficient intakes. We explored associations between iodide intake and urinary iodine concentration (UIC), urinary iodine/creatinine ratio (I/Cr), thyroid stimulating hormone, thyroglobulin, free triiodothyronine, free thyroxine and palpable goiter in a region of mild-to-moderate iodine insufficiency. A total of 246 pregnant women aged 18–40 in Bradford, UK, joined the Health and Iodine in Babies (Hiba) study. They provided detailed information on diet and supplement use, urine and serum samples and were assessed for goiter at around 12, 26 and 36 weeks’ gestation, and 6, 18 and 30 weeks postpartum. Dietary iodide intake from food and drink was estimated using six 24 h recalls. During pregnancy, median (IQR) dietary iodide intake was 101 µg/day (54, 142), with 42% from dairy and 9% from white fish. Including supplements, intake was 143 µg/day (94, 196), with 49% < UK reference nutrient intake (140 µg/day). Women with Pakistani heritage had 129 µg/day (87, 190) median total intake. Total intake during pregnancy was associated with 4% (95% CI: 1%, 7%) higher UIC, 5% (3%, 7%) higher I/Cr, 4% (2%, 6%) lower thyroglobulin and 21% (9%, 32%) lower odds of palpable goiter per 50 µg/day. This cohort consumed less iodide in pregnancy than UK and World Health Organization dietary recommendations. UIC, I/Cr and thyroglobulin were associated with intake. Higher intake was associated with fewer goiters. Because dairy was the dominant source of iodide, women following plant-based or low-dairy diets may be at particular risk of iodine insufficiency.

Maternal Iodine Status and Birth Outcomes: A Systematic Literature Review and Meta-Analysis

“…Of these, 53 were identified as potentially relevant after screening of titles and abstracts (with 89% agreement between reviewers) and 26 were identified as relevant following reading of the full texts (with 80% agreement between reviewers). These publications reported on 24 cohorts containing 42,503 participants ( Figure 1 , Supplementary Table S2 ) [ 11 , 12 , 13 , 14 , 16 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ].…”

“…Information was also extracted from published study protocols or cohort profiles where necessary. For three studies, investigators were contacted for additional data [ 12 , 13 , 16 ]. Non-English language and unpublished articles and abstracts were excluded.…”

Essentiality of Trace Elements in Pregnancy, Fertility, and Gynecologic Cancers—A State-of-the-Art Review

“…Fifty percent of Europe is still slightly iodine deficient, while iodine intakes in other developed nations, like the United States and Australia, have decreased in recent years by introducing iodized salt; the FDA has approved the use of potassium iodide and cuprous iodide for salt iodization [ 201 , 202 ]. Iodine deficiency disorders are listed under specialized criteria relating to infertility and are associated with abortions, stillbirths, and congenital anomalies [ 200 , 203 ], this being a tender subject for unexplained circumstances.…”

The effect of sodium restriction on iodine prophylaxis: a review

“…Of note, iodine excess can be also found, mostly due to high iodine content in tap water [48][49][50][51]. In many countries (Continental Europe, the UK and the US), the primary sources of iodine are dairy products and fortified table salt [52][53][54][55][56][57]. Elsewhere, especially in the Middle East, dietary iodine mainly comes from fortified flour and salt [58].…”