Editorial: Consequences of Iodine Deficiency in Pregnancy

IntroductionAn Israeli national survey found that 85% of pregnant women had urinary iodine content (UIC) levels below the adequacy range (<150 µg/L). Widespread desalinated water usage and no national fortification plan are possible causes. Studies assessing relationships between iodine status and maternal and neonatal thyroid function provided varying results. Our aims were to determine whether iodine deficiency was associated with altered maternal or neonatal thyroid function and the factors leading to iodine deficiency.MethodsA cross-sectional study including 100 healthy women without prior thyroid disease, in their first trimester of a singleton pregnancy were recruited from an HMO clinic in central Israel. The women were followed from their first trimester. All women completed a 24-h dietary recall and life habits questionnaires. We tested for UIC, maternal and neonatal thyroid function, maternal autoantibodies, and neonatal outcomes.ResultsMedian UIC in our cohort was 49 µg/L [25%–75% interquartile range (IQR) 16-91.5 µg/L], with 84% below adequacy range. No correlation was found between iodine deficiency and maternal or neonatal thyroid function which remained within normal ranges. Antibody status did not differ, but thyroglobulin levels were significantly higher in iodine insufficient subjects. UIC was higher in women consuming an iodine containing supplement. There was no association between UIC and dietary iodine content or water source.ConclusionsModerate iodine deficiency is common in our healthy pregnant women population. Our data imply that moderate iodine deficiency in pregnancy seem sufficient to maintain normal maternal and neonatal thyroid function.

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Iodine deficiency in pregnancy, infancy and childhood and its consequences for brain development

Best Practice & Research Clinical Endocrinology & Metabolism ◽

10.1016/j.beem.2009.09.002 ◽

2010 ◽

Vol 24 (1) ◽

pp. 29-38 ◽

Cited By ~ 94

Author(s):

Alida Melse-Boonstra ◽

Nidhi Jaiswal

Keyword(s):

Brain Development ◽

Iodine Deficiency ◽

Infancy And Childhood ◽

Iodine Deficiency In Pregnancy ◽

In Pregnancy

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Iodine in pregnancy and breastfeeding

10.1093/med/9780198722700.003.0019 ◽

2015 ◽

Author(s):

Sir Peter Gluckman ◽

Mark Hanson ◽

Chong Yap Seng ◽

Anne Bardsley

Keyword(s):

Thyroid Gland ◽

Thyroid Hormones ◽

Iodine Deficiency ◽

Attention Deficit Disorder ◽

Fetal Brain ◽

Iodine Intake ◽

Food Sources ◽

Increased Risk ◽

Iodine Deficiency In Pregnancy ◽

In Pregnancy

Iodine is a key component of thyroid hormones. Development of the fetal brain and nervous system are dependent on thyroid hormones supplied by the mother via the placenta, increasing the maternal demand for iodine throughout pregnancy. Women with adequate iodine intake before conception (~150 #amp;#x03BC;g/day) can adapt to the increased demand for thyroid hormones during pregnancy, because the thyroid gland adjusts its hormonal output; but this depends on sufficient availability of dietary iodine and the integrity of the thyroid gland. Iodine deficiency causes congenital hypothyroidism, and in severe form, the irreversible brain damage associated with cretinism. Moderate iodine deficiency in pregnancy is associated with lower learning capacity, reduced IQ, hearing impairment, and increased risk of attention deficit disorder. Pregnant women should take a daily multivitamin that contains 150 #amp;#x00B5;g of iodine, unless they regularly consume concentrated food sources of iodine.

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Insufficient iodine nutrition status and the risk of pre-eclampsia: a protocol for systematic review and meta-analysis

BMJ Open ◽

10.1136/bmjopen-2018-025573 ◽

2019 ◽

Vol 9 (5) ◽

pp. e025573 ◽

Cited By ~ 1

Author(s):

Charles Bitamazire Businge ◽

Namhla Madini ◽

Benjamin Longo-Mbenza ◽

A P Kengne

Keyword(s):

Iodine Deficiency ◽

Meta Analysis ◽

Iodine Intake ◽

Nutrition Status ◽

Iodine Nutrition ◽

Populations At Risk ◽

Increased Risk ◽

Geographical Regions ◽

Iodine Deficiency In Pregnancy ◽

In Pregnancy

IntroductionPre-eclampsia is one of the leading causes of maternal and perinatal morbidity and mortality worldwide. Although subclinical hypothyroidism (SCH) in pregnancy is one of the established risk factors for pre-eclampsia, the link between iodine deficiency, the main cause of hypothyroidism and pre-eclampsia remains uncertain. About two billion people live in areas with iodine insufficiency. The increased renal blood flow during pregnancy leading to increased renal iodine clearance together with the increased placental transfer of iodine to the fetus leads to further iodine deficiency in pregnancy. Iodine is one of the most potent exogenous antioxidants whose deficiency is associated with oxidant imbalance and endothelial dysfunction, one of the mechanisms associated with increased risk of pre-eclampsia.Methods and analysisA systematic search of published literature will be conducted for case–control studies that directly determined the iodine nutrition status of women with pre-eclampsia and appropriate normotensive controls. A similar search will be conducted for cohort studies in which the incidence of pre-eclampsia among pregnant women with adequate and inadequate iodine nutrition status was reported. Databases including MEDLINE, EMBASE, Google Scholar, SCOPUS and Africa Wide Information will be searched up to 31 December 2018. Screening of identified articles and data extraction will be conducted independently by two investigators. Risk of bias of the included studies will be assessed using a Newcastle-Ottawa Scale. Appropriate meta-analytic techniques will be used to pool prevalence and incidence rates, odds and relative risk of pre-eclampsia from studies with similar features, overall and by geographical regions. Heterogeneity of the estimates across studies will be assessed and quantified and publication bias investigated. This protocol is reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis protocols (PRISMA-P) 2015 guidelines.Ethics and disseminationSince the proposed study will use published data, there is no requirement for ethical approval. This review seeks to identify the risk of pre-eclampsia associated with insufficient iodine nutrition in pregnancy. This will help to ascertain whether insufficient iodine intake may be an independent risk factor for pre-eclampsia. This will advise policy makers on the possibility of maximising iodine nutrition in pregnancy and reproductive age as one of the remedies for prevention of pre-eclampsia among populations at risk of inadequate iodine intake. This review is part of the thesis that will be submitted for the award of a PhD in Medicine to the Faculty of Health Sciences of the University of Cape Town. In addition the results will be published in a peer-reviewed journal.PROSPERO registration numberCRD42018099427.

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