Iodine Supplementation In Pregnancy Research Articles

Noncompliance to iodine supplementation recommendation is a risk factor for iodine insufficiency in Portuguese pregnant women: results from the IoMum cohort.

After a recommendation for iodine supplementation in pregnancy has been issued in 2013 in Portugal, there were no studies covering iodine status in pregnancy in the country. The aim of this study was to assess iodine status in pregnant women in Porto region and its association with iodine supplementation. A cross-sectional study was conducted at Centro Hospitalar Universitário São João, Porto, from April 2018 to April 2019. Pregnant women attending the 1st trimester ultrasound scan were invited to participate. Exclusion criteria were levothyroxine use, gestational age < 10 and ≥ 14weeks, non-evolutive pregnancy at recruitment and non-signing of informed consent. Urinary iodine concentration (UIC) was measured in random spot urine by inductively coupled plasma-mass spectrometry. Median UIC was 104μg/L (IQR 62-189) in the overall population (n = 481) of which 19% had UIC < 50µg/L. Forty three percent (n = 206) were not taking an iodine-containing supplement (ICS) and median UIC values were 146µg/L (IQR 81-260) and 74µg/L (IQR 42-113) in ICS users and non-users, respectively (p < 0.001). Not using an ICS was an independent risk factor for iodine insufficiency [adjusted OR (95% CI) = 6.00 (2.74, 13.16); p < 0.001]. Iodised salt use was associated with increased median iodine-to-creatinine ratio (p < 0.014). A low compliance to iodine supplementation recommendation in pregnancy accounted for a mild-to-moderately iodine deficiency. Our results evidence the need to support iodine supplementation among pregnant women in countries with low household coverage of iodised salt. Trial registration number NCT04010708, registered on the 8th July 2019.

Iodine Supplementation in Pregnancy in an Iodine-Deficient Region: A Cross-Sectional Survey.

Iodine deficiency is a common problem in pregnant women and may have implications for maternal and child health. Iodine supplementation during pregnancy has been recommended by several scientific societies. We undertook a cross-sectional survey to assess the efficacy of these recommendations in a European iodine-deficient region. Urinary iodine concentrations (UIC) were determined in pregnant women before (n = 203) and after (n = 136) the implementation of guidelines for iodine supplementation in pregnancy. Iodine supplementation (200 μg/day) reduced the proportion of pregnant women with severe iodine deficiency (37.4% to 18.0%, p = 0.0002). The median UIC increased from 67.6 µg/L to 106.8 µg/L but remained below the recommended target level (>150 µg/L) for pregnant women. In conclusion, iodine supplementation in pregnant women improved iodine status in this iodine-deficient region but was insufficient to achieve recommended iodine levels in pregnancy. Additional measures, such as the adjustment of the dose or timing of supplementation, or universal salt iodization, may be needed.

Gebelikte Folik Asit, B12 Vitamini, D Vitamini ve İyot Destekleri Kullanmak Gerekli Midir? Olası Riskler

Gebelik sürecinde artan gereksinimler dolayısıyla; özellikle bazı mikro besin ögelerinin besin desteği olarak alınması ve böylece yetersizlik ile ilişkili risklerinin en aza indirilmesi, maternal ve fetal sağlığın korunmasında büyük öneme sahiptir. Gebelikte, besin ögelerinin ciddi veya orta düzeyde yetersizliğinde, hayat kurtarıcı nitelikte olan destekler; hafif yetersizlik veya maternal depoların yeterli olduğu koşullarda, çeşitli riskleri de beraberinde getirmektedir. Doğumsal anomalilerin önlenmesinde etkisi kanıtlanmış olan folik asitin maternal dönemde fazla alımı durumunda kanserojeniteyi tetikleyebileceği, çinko emilimini olumsuz etkileyebileceği, B12 vitamini eksikliğinin tanısında ve tedavisinde gecikmelere yol açabileceği, çocukluk çağı astım, alerji riski ile ilişkili olabileceği görülmüştür. Eksikliği fetal anomaliler ile ilişkilendirilen bir diğer vitamin olan B12’nin toksik etkisi bildirilmemekle birlikte literatür taramasında fazla alımı durumunda alerjik reaksiyonlar gösteren bir vaka raporuna rastlanmıştır. Yenidoğan hipokalsemisi ve raşitizmin önlenmesinde etkili D vitamini desteğinin fazla alımı teratojen etki gösterebilir. İyot yetersizliği ile ilişkili kretenizm gibi hastalıkların önlenmesinde etkili olan iyot desteğinin fazla alımının gebenin tiroid disfonksiyonuna, gebelikteki subklinik ve aşikâr hipotiroidizm prevalansında artışa yol açabileceği ve bebeğin psikomotor gelişimini olumsuz etkileyebileceği belirtilmiştir. Gebelikte önerilen dozlarda besin desteklerinin kullanımı uygundur ancak yetersizliğin önlenmesi kadar fazla alım konusunda da dikkatli olunmalıdır. Bu derlemede; gebelikte yaygın olarak kullanılan folik asit, B12 vitamini, D vitamini ve iyot besin desteklerinin fazla alımına ilişkin riskler tartışılmıştır.

Effect of iodine supplementation in pregnancy on neurocognitive development on offspring in iodine deficiency areas: a systematic review.

To investigate the effect of iodine supplementation during gestation on the neurocognitive development of children in areas where iodine deficiency is common. Based on the PRISMA methodology, we conducted the search for articles in the PubMed, LILACS and Scopus databases, between March and April 2020, without limitation of dates. We used descriptors in English, Portuguese, and Spanish, without filters. Four clinical trials and four cohort articles were included in the review. The maximum supplementation was 300 μg of potassium iodide per day. The Bayley scale and Children's Communication Checklist-Short were used to assess neurodevelopment in children. There was no significant improvement in the children's mental development index and behavioural development index in the supplemented group; however, the psychomotor development index (PDI) showed improvement in the poorer gross motor skills. We found differences in the response time to sound in the supplemented group living in mild deficiency areas. Daily supplementation with iodine can improve poor psychomotor development of children living in mild to moderate iodine deficiency areas. Thus, it is necessary to perform further studies to assess the effect of supplementation on neurodevelopment before, during and after gestation in mild to moderate iodine deficiency areas.

Mild to moderate iodine deficiency in pregnancy: A matter of debate

During the last few decades painstaking efforts have been made to eliminate iodine deficiency through the world. Nowadays in regions where dietary iodine intake is adequate or borderline, the main focus is increasing dietary iodine supply in the target population during pregnancy and the first years of life. Severe iodine deficiency during pregnancy increases the risk of irreversible brain damage, intellectual disability, neurologic abnormalities, stunted growth, increased pregnancy loss, infant mortality, impairments in child development and cretinism. The potential effects of mild-to-moderate iodine deficiency are debated. Results from animal studies and observational human studies indicate that maternal mild-to-moderate iodine deficiency disturbs thyroid function in pregnancy and it also may affects fetal neurodevelopment. The effect of supplementation of iodine on thyroid function of pregnant women and their newborn, neurodevelopment of infants and cognitive performance of children have been investigated using iodine nutrition in pregnancy, based on median urinary iodine concentration. However they have found conflicting results regarding the benefits or harms of iodine supplementation in pregnancy. Although many epidemiological, interventional and clinical studies have supported the association between thyroid function in pregnant women and later psychomotor and mental development of their children, the effect of iodine supplementation in pregnant women on neurodevelopment of children is inconclusive. Even in areas with well-established universal salt iodization program, pregnancy could be at risk of having iodine deficiency and despite WHO/ICCIDD/UNICEF recommendation which believe that dietary iodine fortification during pregnancy depends primarily on the extent of pre-existing iodine deprivation, systematic dietary fortification needs to be implemented in this vulnerable group. However, iodine supplementation of mildly iodine deficient pregnant women may not have beneficial effects in their thyroid function or neurodevelopment of their children.

Effects of iodine supplementation during pregnancy on pregnant women and their offspring: a systematic review and meta-analysis of trials over the past 3 decades.

The current systematic review aimed to provide comprehensive data on the effects of iodine supplementation in pregnancy and investigate its potential benefits on infant growth parameters and neurocognitive development using meta-analysis. A systematic review was conducted on trials published from January 1989 to December 2019 by searching MEDLINE, Web of Science, the Cochrane Library, Scopus, and Google Scholar. For most maternal and neonatal outcomes, a narrative synthesis of the data was performed. For birth anthropometric measurements and infant neurocognitive outcomes, the pooled standardized mean differences (SMDs) with 95% CIs were estimated using fixed/random effect models. Fourteen trials were eligible for inclusion in the systematic review, of which five trials were included in the meta-analysis. Although the findings of different thyroid parameters are inconclusive, more consistent evidence showed that iodine supplementation could prevent the increase in thyroglobulin concentration during pregnancy. In the meta-analysis, no differences were found in weight (-0.11 (95% CI: -0.23 to 0.01)), length (-0.06 (95% CI: -0.21 to 0.09)), and head circumference (0.26 (95% CI: -0.35 to 0.88)) at birth, or in cognitive (0.07 (95% CI: -0.07 to 0.20)), language (0.06 (95% CI: -0.22 to 0.35)), and motor (0.07 (95% CI: -0.06 to 0.21)) development during the first 2 years of life in infants between the iodine-supplemented and control groups. Iodine supplementation during pregnancy can improve the iodine status in pregnant women and their offspring; however, according to our meta-analysis, there was no evidence of improved growth or neurodevelopmental outcomes in infants of iodine-supplemented mothers.

Supplementation in pregnancy: determinants of the compliance with guidelines in Portugal, 2019

Abstract Background Folic acid (FA) and iodine supplementation in pregnancy are nutritional interventions recommended by the World Health Organization, which are widespread in Portugal. Since there isn`t available reimbursed medicine containing only 400µg of FA and the increasing evidence that excessive supplementation in FA can lead to adverse outcomes for mothers and their offspring, make interesting to assess the clinical practice. Therefore, it`s important to understand the actual adherence to FA and iodine supplementation in periconceptional period, as well as to identify its determinants. Methods Telephonic interviews (n = 140) were conducted with mothers enrolled in Primary Health Centers, recruited in their children's vaccination appointment (aged 0-6 months). Among the variables studied are sociodemographic, medical and obstetric history, diet and supplements used during pregnancy. Data were analyzed using the Statistical Package for Social Sciences® program. Results The prevalence of iodine and FA supplementation among mothers was high (98%). About 3/4 of the interviewees reported having planned their pregnancy, and of these, 1/4 did not have a preconception consultation. The first pregnancy consultation took place at 6-10 weeks, on average. FA supplementation has the greatest discrepancies with the guidelines: only 29% (n = 40) started at the recommended time, 3% (n = 4) stopped at 12 weeks of pregnancy, and only 33% (n = 34) had 400µg of FA. Fifty one percent of the mothers indicated that they were unaware that they should start supplementation before the interruption of the contraceptive method. Conclusions These results suggest the need for enhanced antenatal care and interventions that increase women's health literacy. Public Health strategies in order to increase preconception consultations are needed as well as a national joint effort towards the homogenization of clinical practices regarding the prescription of supplementation in pregnancy. Key messages Folic acid (FA) and iodine supplementation in pregnancy are widespread practices in Portugal despite the fact that no available reimbursed medicine containing the recommended 400 µg of FA is available. Antenatal care and women's health literacy should be improved in order to comply with the recommendations, as well as the availability of a reimbursed medicine containing 400µg of folic acid.

Systematic review and meta-analysis of the effects of iodine supplementation on thyroid function and child neurodevelopment in mildly-to-moderately iodine-deficient pregnant women

Mild-to-moderate iodine deficiency, particularly in pregnancy, is prevalent; this is of concern because observational studies have shown negative associations with child neurodevelopment. Although neither the benefits nor the safety of iodine supplementation in pregnancy in areas of mild-to-moderate deficiency are well researched, such supplementation is increasingly being recommended by health authorities in a number of countries. By reviewing the most recent published data on the effects of iodine supplementation in mildly-to-moderately deficient pregnant women on maternal and infant thyroid function and child cognition, we aimed to determine whether the evidence was sufficient to support recommendations in these areas. A systematic review of randomized controlled trials (RCTs), non-RCT interventions, and observational studies was conducted. To identify relevant articles, we searched the PubMed and Embase databases. We defined mild-to-moderate iodine deficiency as a baseline median urinary iodine concentration (UIC) of 50-149 µg/L. Eligible studies were included in meta-analyses. In total, 37 publications were included-10 RCTs, 4 non-RCT interventions, and 23 observational studies. Most studies showed no effect of iodine supplementation on maternal or infant thyroid-stimulating hormone and free thyroxine. Most RCTs found that supplementation reduced maternal thyroglobulin and in 3 RCTs, it prevented or diminished the increase in maternal thyroid volume during pregnancy. Three RCTs addressed child neurodevelopment; only 1 was adequately powered. Meta-analyses of 2 RCTs showed no effect on child cognitive [mean difference (MD): -0.18; 95% CI: -1.22, 0.87], language (MD: 1.28; 95% CI: -0.28, 2.83), or motor scores (MD: 0.28; 95% CI: -1.10, 1.66). There is insufficient good-quality evidence to support current recommendations for iodine supplementation in pregnancy in areas of mild-to-moderate deficiency. Well-designed RCTs, with child cognitive outcomes, are needed in pregnant women who are moderately deficient (median UIC<100 µg/L). Maternal intrathyroidal iodine stores should be considered in future trials by including appropriate measures of preconceptional iodine intake.This review was registered at www.crd.york.ac.uk/prospero as CRD42018100277.

The Effects of Iodine Supplementation in Pregnancy on Iodine Status, Thyroglobulin Levels and Thyroid Function Parameters: Results from a Randomized Controlled Clinical Trial in a Mild-to-Moderate Iodine Deficiency Area.

Background: Iodine supplementation during pregnancy in areas with mild-to-moderate iodine deficiency is still debated. Methods: A single-center, randomized, single-blind and placebo-controlled (3:2) trial was conducted. We enrolled 90 women before 12 weeks of gestation. From enrollment up until 8 weeks after delivery, 52 women were given an iodine supplement (225 ug/day, potassium iodide tablets) and 38 were given placebo. At recruitment (T0), in the second (T1) and third trimesters (T2), and 8 weeks after delivery (T3), we measured participants’ urinary iodine-to-creatinine ratio (UI/Creat), thyroid function parameters (thyroglobulin (Tg), TSH, FT3, and FT4), and thyroid volume (TV). The newborns’ urinary iodine concentrations were evaluated in 16 cases. Results: Median UI/Creat at recruitment was 53.3 ug/g. UI/Creat was significantly higher in supplemented women at T1 and T2. Tg levels were lower at T1 and T2 in women with UI/Creat ≥ 150 ug/g, and in the Iodine group at T2 (p = 0.02). There was a negative correlation between Tg and UI/Creat throughout the study (p = 0.03, r = −0.1268). A lower TSH level was found in the Iodine group at T3 (p = 0.001). TV increased by +Δ7.43% in the Iodine group, and by +Δ11.17% in the Placebo group. No differences were found between the newborns’ TSH levels on screening the two groups. Conclusion: Tg proved a good parameter for measuring iodine intake in our placebo-controlled series. Iodine supplementation did not prove harmful to pregnancy in areas of mild-to-moderate iodine deficiency, with no appreciable harmful effect on thyroid function.

A Randomized Controlled Trial of the Correlation between Iodine Supplementation in Pregnancy and Maternal Urine Iodine and Neonatal Thyroid Stimulating Hormone Levels

Objective: To establish the correlation of maternal urine iodine and neonatal thyroid stimulating hormone (TSH) in iodine supplemented and non-iodine supplemented pregnant women. Materials and Methods: The study was a prospective, randomized, controlled trial, which was conducted at the antenatal care unit, labor ward, and neonatal unit of Siriraj Hospital, Mahidol University, Bangkok, Thailand. In all, 224 pregnant women were recruited during 1 October 2015 and 31 July 2017. They were randomized into 2 groups: an iodine and a non-iodine supplemented group. One woman in the control group left the study as she had delivery at another hospital. Results: There were no statistically significant differences in the demographic data, original area of domicile, and adverse neonatal outcomes (including preterm labor and low birth weight) of the patients in the two groups. The maternal urinary iodine levels were 84.14 + 61.85 and 58.41 + 41.36 microgram/L, and the median values of the neonatal TSH levels were 3.7 + 1.87 and 4.4 + 1.99 mIU/ml, in the iodine and non-iodine supplemented groups, respectively. The differences in both values were statistically significant (p-value < 0.05). Conclusion: This study determined that there were statistically significant differences in the maternal urinary iodine levels and the median values of the neonatal TSH levels of the iodine and non-iodine replacement groups of pregnant women. Even though there were no clinically significant differences and none of the newborns was diagnosed with hypothyroidism, iodine supplementation in all pregnant women should be considered. A larger prospective, RCT trial would confirm the benefits of a strategy of routinely administering iodine to pregnant women at Siriraj Hospital.

Iodine supplementation in pregnancy and effect on offspring neurodevelopment

Iodine supplementation in pregnancy and effect on offspring neurodevelopment

The effectiveness of iodine supplementation during pregnancies in geographical areas of high prevalence of iodine insufficiency

The objective of this study was to determine the effectiveness of routine iodine supplementation among pregnant women in areas of high prevalence of an iodine insufficiency, using WHO criteria to determine the iodine status. A longitudinal study was conducted on pregnant women attending antenatal care at a tertiary hospital. The urine iodine concentration was measured in the first trimester and after 150 μg of iodine supplementation in the third trimester. A total of 327 pregnant women met the inclusion criteria with a complete follow-up. The prevalence of an iodine insufficiency was significantly lower in the third trimester, when compared to the first trimester (21.41% vs 55.35%, p < .001). However, 21.4% of cases still had an iodine insufficiency and 35.17% had an ‘above-requirement’ in the third trimester. In the areas of high prevalence of iodine insufficiency, an iodine supplementation significantly reduces the number of women with insufficiency; however, it was associated with unnecessarily high UICs, leading to the risk of excess iodine.Impact statementWhat is already known on this subject: Iodine insufficiency is highly prevalent in many geographical areas. Half of the pregnant women in the northern part of Thailand had an iodine insufficiency in the first trimester.What do the results of this study add: Iodine supplementation (daily 150-mcg of potassium iodide) could significantly reduce the number of women with the insufficiency. About one-fifth of women still had an iodine insufficiency in spite of iodine supplementation. Universal supplementation could be associated with unnecessarily high UICs, potentially at risk of iodine excess.What are the implications of these findings for clinical practice and/or further research: Physicians should guard against the occurrence of adverse effect from an iodine excess when there is routine iodine supplementation for pregnant women. Further study is required to establish the best strategy for an iodine supplementation in pregnancy.

Iodine supplementation in pregnancy in mildly deficient regions

It is well known that severe iodine deficiency during pregnancy affects fetal brain development and has implications for cognition in later life, including reduced intelligence quotient (IQ) scores.1 However, the effects of mild-to-moderate deficiency during pregnancy are less well known. Findings of observational studies in mildly-to-moderately iodine-deficient pregnant women have shown an association with lower IQ, reading ability,2 and spelling scores in offspring.3 Although several randomised controlled trials of iodine supplementation in pregnancy have been done in regions of mild-to-moderate iodine deficiency, they did not measure neurodevelopment in offspring.

Iodine supplementation in pregnancy – is it time?

Iodine is essential for the synthesis of thyroid hormone and optimal foetal neurological development. Pregnant women living in borderline or moderate-severe iodine deficient areas are at particularly high risk of being iodine deficient, and this may have important clinical consequences, particularly for the neurocognitive development of the offspring. It is a substantial problem and many countries including the United Kingdom are mild-moderately iodine deficient. Although the detrimental effects of severe iodine deficiency are well recognized, the benefits of correcting mild-to-moderate iodine deficiency are unclear due to a lack of randomized controlled trials in this area. However, observational data increasingly indicate that there may be substantial health and economic benefits from correcting iodine deficiency in pregnancy. There is now a growing trend from learned societies that iodine supplementation should be utilized in pregnancy in countries with mild-to-moderate iodine deficiency. The dose of iodine supplement needs to reflect local iodine status and iodization policies and will need careful monitoring at the population level to ensure doses to prevent under/excess dosing which would undermine the potential benefits. National tailored guidance is therefore essential.

The effect of iodine supplementation in pregnancy on early childhood neurodevelopment and clinical outcomes: results of an aborted randomised placebo-controlled trial.

BackgroundConcern that mild iodine deficiency in pregnancy may adversely affect neurodevelopment of offspring has led to recommendations for iodine supplementation in the absence of evidence from randomised controlled trials. The primary objective of the study was to investigate the effect of iodine supplementation during pregnancy on childhood neurodevelopment. Secondary outcomes included pregnancy outcomes, maternal thyroid function and general health.MethodsWomen with a singleton pregnancy of fewer than 20 weeks were randomly assigned to iodine (150 μg/d) or placebo from trial entry to birth. Childhood neurodevelopment was assessed at 18 months by using Bayley Scales of Infant and Toddler Development (Bayley-III). Iodine status and thyroid function were assessed at baseline and at 36 weeks’ gestation. Pregnancy outcomes were collected from medical records.ResultsThe trial was stopped after 59 women were randomly assigned following withdrawal of support by the funding body. There were no differences in childhood neurodevelopmental scores between the iodine treated and placebo groups. The mean cognitive, language and motor scores on the Bayley-III (iodine versus placebo, respectively) were 99.4 ± 12.2 versus 101.7 ± 8.2 (mean difference (MD) −2.3, 95 % confidence interval (CI) −7.8, 3.2; P = 0.42), 97.2 ± 12.2 versus 97.9 ± 11.5 (MD −0.7, 95 % CI −7.0, 5.6; P = 0.83) and 93.9 ± 10.8 versus 92.4 ± 9.7 (MD 1.4, 95 % CI −4.0, 6.9; P = 0.61), respectively. No differences were identified between groups in any secondary outcomes.ConclusionsIodine supplementation in pregnancy did not result in better childhood neurodevelopment in this small trial. Adequately powered randomised controlled trials are needed to provide conclusive evidence regarding the effect of iodine supplementation in pregnancy.Trials registrationThe trial was registered with the Australian New Zealand Clinical Trials Registry at http://www.anzctr.org.au. The registration number of this trial is ACTRN12610000411044. The trial was registered on 21 May 2010.

Neurotoxicant exposure during pregnancy is a confounder for assessment of iodine supplementation on neurodevelopment outcome

ContextThe developing brain is vulnerable to iodine deficiency (ID) and environmental neuro-toxicants. ObjectivesTo assess neurocognitive development of children whose mothers have received (or not) iodine supplementation during pregnancy, in an area of borderline ID, while assessing in utero exposure to environmental neuro-toxicants. Design/patientsAmong 86 children born from normal euthyroid women who participated in our prospective interventional study on iodine supplementation (150μg/day) started early in pregnancy, 44 (19 with iodine supplementation, 25 controls) were assessed at two years using the Bayley test. Information on parents' education and habits (smoking), and on child development was recorded. Thyroid tests at each trimester of pregnancy and on cord blood (CB) were available, as well as milk concentrations of selected environmental compounds known for their neurotoxicity, including heavy metals and PCBs. ResultsThere was no difference in Bayley tests for children born to mothers with and without iodine supplementation, but sample size was small. Language and Social-Emotional Scales were negatively correlated with TBG at all times tested, while PCB 118 correlated negatively with all Language scales. Among maternal and CB thyroid tests, only CB thyroglobulin, the best marker of iodine status, correlated (negatively) with neurodevelopment scales (Motor and Expressive Language). ConclusionsThis pilot study suggests that PCB118 has a negative impact on neurocognitive development, possibly mitigating the benefit of iodine supplementation in an area of borderline ID. We propose that exposure to environmental neurotoxicants should be taken into account when designing studies on the benefit of iodine supplementation in pregnancy. The potential interactions between TBG, environmental neurotoxicants and brain development warrant further studies.

The importance of iodine in public health.

Iodine (I) deficiency has been known for more than a century and is known to cause cretinism at the extreme end of the spectrum but also, importantly, impaired development and neurocognition in areas of mild deficiency. The WHO has indicated that median urinary iodine of 100-199 μg/l in a population is regarded as indicative of an adequate iodine intake. The understanding of the spectrum of iodine deficiency disorders led to the formation of The International Council for the Control of Iodine Deficiency Disorders which has promulgated the use of household iodized salt and the use of such salt in food processing and manufacture. Iodine deficiency is particularly important in pregnancy as the fetus relies on maternal thyroxine (T4) exclusively during the first 14 weeks and also throughout gestation. As this hormone is critical to brain and nervous system maturation, low maternal T4 results in low child intelligence quotient. The recommendation for I intake in pregnancy is 250 μg/day to prevent fetal and child brain function impairment. During the past 25 years, the number of countries with I deficiency has reduced to 32; these still include many European developed countries. Sustainability of adequate iodine status must be achieved by continuous monitoring and where this has not been performed I deficiency has often recurred. More randomized controlled trials of iodine supplementation in pregnancy are required in mild iodine-deficient areas to inform public health strategy and subsequent government action on suitable provision of iodine to the population at risk.

Effect of iodine supplementation in pregnancy on child development and other clinical outcomes: a systematic review of randomized controlled trials

Routine iodine supplementation during pregnancy is recommended by leading health authorities worldwide, even in countries where the iodine status of the population is sufficient. We evaluated the efficacy and safety of iodine supplementation during pregnancy or the periconceptional period on the development and growth of children. Secondary outcomes included pregnancy outcome and thyroid function. A systematic review of randomized controlled trials (RCTs) was conducted. PUBMED, MEDLINE, EMBASE, CINAHL, PsycINFO, and Cochrane Central Register of Controlled Trials databases were searched to identify relevant RCTs. Fourteen publications that involved 8 trials met the inclusion criteria. Only 2 included trials reported the growth and development of children and clinical outcomes. Iodine supplementation during pregnancy or the periconceptional period in regions of severe iodine deficiency reduced risk of cretinism, but there were no improvements in childhood intelligence, gross development, growth, or pregnancy outcomes, although there was an improvement in some motor functions. None of the remaining 6 RCTs conducted in regions of mild to moderate iodine deficiency reported childhood development or growth or pregnancy outcomes. Effects of iodine supplementation on the thyroid function of mothers and their children were inconsistent. In this review, we highlight a lack of quality evidence of the effect of prenatal or periconceptional iodine supplementation on growth and cognitive function of children. Although contemporary RCTs of iodine supplementation with outcomes addressing childhood development are indicated, conduct of such RCTs may not be feasible in populations where iodine supplementation in pregnancy is widely practiced.

Apparent Insufficiency of Iodine Supplementation in Pregnancy

Pregnant woman are at increased risk for iodine deficiency, which may induce thyroid insufficiency and have damaging effects not only on the mother but also the fetus. We hypothesize that iodine supplementation during pregnancy reduces the risk for iodine deficiency. Cross-sectional study to assess iodine levels in random urine specimens during pregnancy in New York City. One hundred eighty-two women visited a clinic where free iodine supplementation was offered (150 μg of potassium iodide daily; Group A), and 183 women were seen at a practice at which no supplementation was offered (Group B). Overall, more than one out of two pregnant women in New York City were at risk for iodine deficiency with a spot urinary iodine (UI) level less than 150 μg/L and could be defined as at risk for iodine deficiency. The median urine iodine concentration for the entire group was 152.5 μg/L, but there was considerable variation from 10.9 to 1210 μg/L. The median UI level of the supplemented Group A (169.8 μg/L) was significantly greater than that of Group B (128.4 μg/L; p<0.01). Based on World Health Organization (WHO) guidelines, 38.9% of Group B women were at risk for mild, moderate, or severe iodine deficiency, compared with 22.8% of Group A women. New York City pregnant women were significantly less prone to iodine deficiency when provided with iodine supplementation. Nevertheless, when spot UI levels were used to estimate iodine sufficiency, more than 20% of supplemented women were still at risk for iodine deficiency according to WHO guidelines, suggesting that current supplementation practices remain insufficient.

Iodine supplementation in pregnancy and its effect on child cognition

Maternal hypothyroidism and hypothyroxenemia due to iodine deficiency have been shown to affect development of the newborn negatively. Maternal iodine supplementation may therefore improve cognitive performance of the offspring, even in areas of mild-to-moderate iodine deficiency (ID). Several iodine supplementation studies have been performed in mildly ID pregnant women in Europe. These studies have shown that iodine supplementation increases maternal urinary iodine (UI) excretion and reduces thyroid volume, as well as prevents increases in infant thyroid volume and thyroglobuline. However, randomized controlled studies with long-term outcomes are lacking. Therefore, two trials were started in 2008 in areas of low iodine status; one in Bangalore, India (n=325), and another in Bangkok, Thailand (n=514). Pregnant women were recruited <14 weeks gestational age and randomized to either receive a daily dose of 200μg I (as KI) or an identical placebo throughout pregnancy. Both trials are ongoing, and women are followed up during pregnancy and at delivery. UI, thyroid hormones, and thyroid size are measured. Birth outcomes are recorded, such as gestational age at delivery, height, weight, and APGAR scores, and cord blood and heel stick blood (<72h) is collected from the child. Child development is assessed at 6 weeks of age using the Neonatal Behavioral Assessment Scale (NBAS), and at 12 and 24 months of age using the Bayley Scales of Infant Development. The outcomes of these trials will contribute importantly to the evidence base for iodine supplementation of pregnant women living in areas of mild iodine deficiency.