Iodine deficiency in pregnant women in Sweden: a national cross-sectional study

Manousou, Sofia; Andersson, Maria; Eggertsen, Robert; Hunziker, Sandra; Hulthén, Lena; Nyström, Helena Filipsson

doi:10.1007/s00394-019-02102-5

Cited by 24 publications

(30 citation statements)

References 42 publications

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“…However, it is questionable to extrapolate the iodine status of schoolchildren to women of reproductive age, because of possible differences in dietary iodine. Our hypothesis on possible mild ID among pregnant women in Sweden was recently confirmed in a national survey 12 . This emphasizes the need to investigate if lactating women have also become mildly iodine deficient.…”

Section: Introductionsupporting

confidence: 58%

Inadequate iodine intake in lactating women in Sweden: A pilot 1‐year, prospective, observational study

Manousou

Augustin

Eggertsen

et al. 2020

Acta Obstet Gynecol Scand

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Introduction Breastfed infants depend on breast‐milk iodine for growth and brain development, as iodine is a trace element important for thyroid hormone production. Iodine need is higher during lactation; hence, mothers and children are at risk of iodine deficiency. We aimed to explore maternal iodine and thyroidal status during lactation. Material and methods Pregnant women were recruited in Gothenburg, southwest Sweden. Maternal urine and serum were collected at pregnancy week 35‐37 (n = 84) and 0.5, 4, and 12 months postpartum. Seventy mothers provided breast milk at 0.5 months. Results Median (interquartile range) breast‐milk iodine concentration was 90 (66‐116) μg/L. About 58% had breast‐milk iodine concentration <100 μg/L. Iodine supplement users (n = 13) had higher breast‐milk iodine concentration than non‐users (n = 49) (140 μg/L vs 71 μg/L, P = .001). Exclusively breastfeeding women at 4 months postpartum (n = 57) had lower median urinary iodine concentration (85 μg/L vs 133 μg/L, P = .004) and higher thyroglobulin serum concentration (22.3 μg/L vs 11.8 μg/L, P = .032) than non‐exclusively breastfeeding women (n = 25). Concentrations of thyroid hormones were unaffected. Conclusions This pilot study suggests that lactating women in southwest Sweden present mildly inadequate iodine intake, mainly among non‐iodine supplement users and exclusively breastfeeding mothers. Studies on the coverage of the iodine fortification program in breastfeeding women are warranted.

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Section: Introductionsupporting

confidence: 58%

Inadequate iodine intake in lactating women in Sweden: A pilot 1‐year, prospective, observational study

Manousou

Augustin

Eggertsen

et al. 2020

Acta Obstet Gynecol Scand

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“…Additionally adequate iodine intake in school-aged children doesn't assure adequate intake in at risk populations even in a country with a salt iodization program. In Sweden for instance, school age children had adequate iodine intake while pregnant women had inadequate intakes [31].…”

Section: Discussionmentioning

confidence: 99%

Excessive intake of iodine and low prevalence of goiter in school age children five years after implementation of national salt iodization in Shebedino woreda, southern Ethiopia

et al. 2021

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Background Iodine is a trace element required for the synthesis of thyroid hormones. The multiple effects of iodine deficiency on human health are called iodine deficiency disorders (IDDs). IDDs have been common nutritional problems in Ethiopia. In 2012, Ethiopia launched a national salt iodization program to address IDDs. The objective of this study was to assess the effects of this program after 5 years by measuring urinary iodine concentration (UIC) and prevalence of goiter in school age children as well as household salt iodine concentration (SIC). Methods A school-based cross-sectional design was employed. After ethical approval, 408 children from eight randomly selected primary schools provided urine samples. UIC was analyzed by inductively coupled plasma mass spectrophotometry (ICP-MS). A 10 g salt sample was collected from each household of a sampled child. SIC was analyzed with a digital electronic iodine checker (WYD, UNICEF) and goiter was assessed by palpation. Results The mean (±SD) age of the children was 9 ± 2 years. The prevalence of goiter was 4.2% and no child had grade 2 goiter. The median (IQR) UIC was 518 (327, 704) μg/L and UIC ranged from 3.1 to 2530 μg/L. Of the salt samples, 15.6% were not adequately iodized (< 15 ppm), 39.3% were adequately iodized (≥15 to ≤40 ppm), and 45.1% were > 40 ppm. SIC ranged from 4.2 to 195 ppm. Of the mothers, 92% said iodized salt prevents goiter and 8% mentioned prevents mental retardation. Conclusions In 2017 iodine deficiency was no longer a public health problem in the study area. However, the high variability in UIC and SIC and excessive iodine intake are of great concern. It is vital to ensure that salt is homogenously iodized at the production site before being distributed to consumers.

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“…One study reported that women who started taking 150 μg iodine/day (as part of a multivitamin/mineral tablet) had a significantly lower free thyroxine concentrations during pregnancy than women who started using iodized salt before pregnancy ( 31 ). Most cross-sectional studies associating iodine supplements with maternal thyroxine concentrations found no difference in free thyroxine ( 32 – 34 ) or total thyroxine concentrations ( 35 ), although two studies reported lower free thyroxine ( 36 , 37 ) in iodine-supplement users. A large cross-sectional Chinese study (in an iodine-sufficient region) reported higher mUICs during early pregnancy were associated with mild maternal hypothyroidism ( 9 ): among pregnant women ( n = 7,190) at 4–8 wk gestation, spot UICs of 250–499 μg/L and ≥500 μg/L were associated with a 1.7-fold and a 2.2-fold increased risk of subclinical hypothyroidism, respectively, and the latter UIC with a 2.9-fold increased risk of isolated hypothyroxinemia ( 9 ).…”

Section: Discussionmentioning

confidence: 99%

Iodine Supplementation in Mildly Iodine-Deficient Pregnant Women Does Not Improve Maternal Thyroid Function or Child Development: A Secondary Analysis of a Randomized Controlled Trial

et al. 2020

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Background: Iodine deficiency during pregnancy may be associated with lower offspring IQ, but there are few data on the safety and efficacy of maternal iodine supplementation on child development. In a previously reported multi-center randomized trial conducted in Thailand and India, we assessed the effect of iodine supplementation in mildly iodine-deficient pregnant women on offspring development. In this secondary analysis of that trial, we report data only from the Thai pregnant women in the study, who were more iodine deficient at entry. Methods: Pregnant women in Bangkok, Thailand, were randomized to receive daily 200 μg oral iodine or placebo until delivery. We assessed thyroid size and thyroid function during pregnancy and cognitive and motor development at ages 1, 2, and 5.7 years. The trial was registered at www.clinicaltrials.gov/NCT00791466 . Findings: Women ( n = 514) entered the trial between November 2008 and March 2011 at a mean ± SD gestational age of 11 ± 2.8 weeks; their median (IQR) UIC was 112 (75, 170) μg/L. Mean compliance with supplementation was 88%. We assessed 397 mothers in the 3rd trimester, 231 infants at age 2 y, and 157 children at mean age 5.7 y. During pregnancy, there was a slightly greater decrease in free and total thyroxine concentrations in the iodine group ( p < 0.05). At age 2 years, the iodine group had borderline lower scores for combined fine and gross motor function ( p = 0.05), but there were no other significant differences in development. At 5.7 years, there were no significant group differences in child development. Conclusion: Daily iodine supplementation in mildly iodine deficient pregnant women was associated with small negative effects on maternal thyroxine concentrations, but did not affect child development. The safety and efficacy of iodine supplementation in mildly-iodine deficient pregnant women needs to be evaluated further in large randomized controlled trials.

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Iodine deficiency in pregnant women in Sweden: a national cross-sectional study

Cited by 24 publications

References 42 publications

Inadequate iodine intake in lactating women in Sweden: A pilot 1‐year, prospective, observational study

Inadequate iodine intake in lactating women in Sweden: A pilot 1‐year, prospective, observational study

Excessive intake of iodine and low prevalence of goiter in school age children five years after implementation of national salt iodization in Shebedino woreda, southern Ethiopia

Iodine Supplementation in Mildly Iodine-Deficient Pregnant Women Does Not Improve Maternal Thyroid Function or Child Development: A Secondary Analysis of a Randomized Controlled Trial

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