Iodine Deficiency In Pregnant Women Research Articles

Mild & moderate iodine deficiency in pregnant women from sub-himalayan regions of india: impact on thyroid status

Mild & moderate iodine deficiency in pregnant women from sub-himalayan regions of india: impact on thyroid status

Pregnant women at risk for iodine deficiency but adequate iodine intake in school-aged children of Zhejiang Province, China

The median urinary iodine concentration (UIC) of school-aged children has been commonly used as a surrogate to assess iodine status of a population including pregnant women. However, pregnant women have higher iodine requirements than children due to increased production of thyroid hormones. The aim of the study was to evaluate the iodine status of pregnant women and children as well as their household salt iodine concentration (SIC) in Quzhou, Zhejiang Province, China. Eligible pregnant women and children from all six counties of Quzhou in 2021 were recruited into the study. They were asked to complete a socio-demographic questionnaire and provide both a spot urine and a household table salt sample for the determination of UIC and SIC. A total of 629 pregnant women (mean age and gestation weeks of 29.6 years and 21.6 weeks, respectively) and 1273 school-aged children (mean age of 9 years and 49.8% of them were females) were included in the study. The overall median UIC of pregnant women and children in our sample was 127 (82, 193) μg/L and 222 (147, 327) μg/L, respectively, indicating sufficient iodine status in children but a risk of mild-to-moderate iodine deficiency in pregnant women. Distribution of iodine nutrition in children varied significantly according to their sex and age (P < 0.05). The rate of adequately household iodised salt samples (18–33 mg/kg) provided by pregnant women and children was 92.4% and 90.6%, respectively. In conclusion, our results indicated a risk of insufficient iodine status in pregnant population of China, but iodine sufficiency in school-aged children. Our data also suggested that median UIC of children may not be used as a surrogate to assess iodine status in pregnant women.

Iodineminho Study: Iodine Supplementation and Prevalence of Iodine Deficiency In Pregnant Women.

Iodine is necessary for proper brain development. The prevalence of iodine deficiency in Portuguese pregnant women led the health authorities, in 2013, to recommend iodine supplementation for women in preconception, throughout pregnancy, and during lactation. This work aimed to assess the effect of iodine supplementation initiated in the preconception or the first trimester of pregnancy on the prevalence of iodine deficiency and maternal thyroid status. An observational prospective cohort study was conducted that followed the thyroid function and iodine status of women recruited during preconception or in the first trimester of pregnancy. Median urinary iodine concentration (UIC) was significantly higher among women taking iodine supplements (no-supplement group UIC = 63 µg/L; supplement group UIC = 100 µg/L; P = .002) but still below the levels recommended by the World Health Organization. Only 15% of pregnant women had adequate iodine status and 17% showed a UIC of less than 50 µg/L. There was no influence whether iodine supplementation was started during preconception or during the first trimester of gestation (UIC preconception group: 112 µg/L vs UIC pregnancy group: 91 µg/L; P = .569). In the first trimester of pregnancy, total thyroxine levels were lower and free triiodothyronine levels were higher in nonsupplemented women. Thyroglobulin levels were lower in women who started iodine supplementation during preconception compared to nonsupplemented women and women who started iodine supplementation during gestation. In the Minho region of Portugal, fertile women have insufficient iodine intake. Additional public health measures are needed since the current recommendations for iodine supplementation for pregnancy are unsatisfactory to achieve adequate iodine status.

Iodine Deficiency, Maternal Hypothyroxinemia and Endocrine Disrupters Affecting Fetal Brain Development: A Scoping Review.

This scoping review critically discusses the publications of the last 30 years on the impact of mild to moderate iodine deficiency and the additional impact of endocrine disrupters during pregnancy on embryonal/fetal brain development. An asymptomatic mild to moderate iodine deficiency and/or isolated maternal hypothyroxinemia might affect the development of the embryonal/fetal brain. There is sufficient evidence underlining the importance of an adequate iodine supply for all women of childbearing age in order to prevent negative mental and social consequences for their children. An additional threat to the thyroid hormone system is the ubiquitous exposure to endocrine disrupters, which might exacerbate the effects of iodine deficiency in pregnant women on the neurocognitive development of their offspring. Ensuring adequate iodine intake is therefore essential not only for healthy fetal and neonatal development in general, but it might also extenuate the effects of endocrine disruptors. Individual iodine supplementation of women of childbearing age living in areas with mild to moderate iodine deficiency is mandatory as long as worldwide universal salt iodization does not guarantee an adequate iodine supply. There is an urgent need for detailed strategies to identify and reduce exposure to endocrine disrupters according to the "precautional principle".

Exploration of thyroglobulin as a biomarker of iodine status in iodine-sufficient and mildly iodine-deficient pregnant women

PurposeUrinary iodine-to-creatinine ratio (UI/Creat) reflects recent iodine intake but has limitations for assessing habitual intake. Thyroglobulin (Tg) concentration, which increases with thyroid size, appears to be an indicator of longer-term iodine status in children and adults, however, less is known in pregnancy. This study investigated the determinants of serum-Tg in pregnancy and its use as an iodine-status biomarker in settings of iodine-sufficiency and mild-to-moderate deficiency.MethodsStored blood samples and existing data from pregnant women from the Netherlands-based Generation R (iodine-sufficient) and the Spain-based INMA (mildly-to-moderately iodine-deficient) cohorts were used. Serum-Tg and iodine status (as spot-urine UI/Creat) were measured at median 13 gestational weeks. Using regression models, maternal socio-demographics, diet and iodine-supplement use were investigated as determinants of serum-Tg, as well as the association between UI/Creat and serum-Tg.ResultsMedian serum-Tg was 11.1 ng/ml in Generation R (n = 3548) and 11.5 ng/ml in INMA (n = 1168). When using 150 µg/g threshold for iodine deficiency, serum-Tg was higher in women with UI/Creat < 150 vs ≥ 150 µg/g (Generation R, 12.0 vs 10.4 ng/ml, P = 0.010; INMA, 12.8 vs 10.4 ng/ml, P < 0.001); after confounder adjustment, serum-Tg was still higher when UI/Creat < 150 µg/g (regression coefficients: Generation R, B = 0.111, P = 0.050; INMA, B = 0.157, P = 0.010). Iodine-supplement use and milk intake were negatively associated with serum-Tg, whereas smoking was positively associated.ConclusionThe association between iodine status and serum-Tg was stronger in the iodine-deficient cohort, than in the iodine-sufficient cohort. Serum-Tg might be a complementary (to UI/Creat) biomarker of iodine status in pregnancy but further evidence is needed.

Iodine status of pregnant women in iodine-sufficient regions: A tertiary care unit experience.

The recommended urinary iodine concentration (UIC) levels in the overall adult population is 100-199 μg/L whereas 150-249 μg/L in pregnant women. The objective is to determine the prevalence and severity of iodine deficiency in pregnant women in Amasya, which is located in the Western Black Sea region in Turkey, where sufficient iodine levels were achieved in the normal population. In this single-center study, we retrospectively searched hospital patient records and identified pregnant women who were assessed for iodine levels between January 2019 and January 2021. A total of 408 pregnant women were found eligible for the study. Thyroid-stimulating hormone (TSH), free triiodothyronine, free thyroxine, antithyroid peroxidase antibodies, and antithyroglobulin antibodies in serum samples and UIC were evaluated and compared between the trimesters. Insufficient iodine intake in pregnancy was defined as UIC <150 μg/L. Median UIC and median TSH levels were 129 (range 45-452) μg/L and 2.98 (range 0.01-71.2) μIU/ml, respectively. 81.1% of pregnant women had UIC <150 μg/L. Iodine intake was adequate in 17.4% of pregnant whereas excessive in 1.5%. Prevalence of iodine deficiency during 1st, 2nd, and 3rd trimesters were 82.1%, 82.4%, and 74.5%, respectively. There was no significant difference in UIC levels between trimesters (P = 0.399). 72.9% of pregnant womens had TSH >2.5 mIU/L in the 1st trimester. Iodine deficiency in pregnancy may exist in an iodine-sufficient population. Appropriate measures must be taken to ensure sufficient iodine levels in these individuals.

Iodine intake and neonatal thyroid function: A never-ending story

Iodine deficiency in pregnant women can lead to abortion, dysgravidy, intrauterine growth restriction, premature birth, low birth weight, which places the pregnant woman in a group with increased vulnerability to the lack of adequate amounts of iodine. Iodine deficiency in pregnancy can lead to increased perinatal and infant mortality and the prevalence of congenital anomalies. All these aspects shed new light on the many side effects of iodine deficiency during pregnancy. The present paper aligns with the general trend of assessing the maternal-fetal thyroid hormone status and establishing the most accurate indicators for its quantification and taking into account the degree of iodine deficiency and prematurity.

Iron Deficiency Is a Risk Factor for Thyroid Dysfunction During Pregnancy: A Population-Based Study in Belgium.

Background: Iron deficiency affects thyroid hormone synthesis by impairing the activity of the heme-dependent thyroid peroxidase. The prevalence of iron deficiency is elevated particularly in pregnant women. This study aimed to investigate the effects of iron status on thyroid function in a nationally representative sample of mildly iodine-deficient pregnant women. Methods: The study population comprised a sample of pregnant women in Belgium during the first and third trimesters of pregnancy (n = 1241). Women were selected according to a multistage proportional-to-size stratified and clustered sampling design. Urine and blood samples were collected, and a questionnaire was completed face to face with the study nurse. Concentrations of free thyroxine (fT4), total thyroxine (T4), free triiodothyronine, thyrotropin (TSH), thyroglobulin (Tg), thyroid peroxidase antibodies, Tg antibodies, hemoglobin, serum ferritin (SF), soluble transferrin receptor, urinary iodine concentrations (UICs) were measured and body iron stores (BIS) were calculated. Results: Median UICs were 117 and 132 μg/L in the first and third trimesters of pregnancy, respectively (p < 0.05). The frequency of SF <15 μg/L was 6.2% in the first trimester and 39.6% in the third trimester of pregnancy (p < 0.05). UIC was a significant predictor of serum Tg concentrations (p < 0.01) but not of thyroid hormone or TSH concentrations. The frequency of fT4<percentile 10th in the third trimester of pregnancy was 24% and 14% in pregnant women with negative BIS and positive BIS, respectively (p < 0.05). SF and BIS were significant predictors of fT4 and T4 in the first trimester of pregnancy (p < 0.05). Hemoglobin was a significant predictor of fT4 in both trimesters (p < 0.01) and for T4 in the third trimester (p = 0.015). Conclusion: Iron deficiency, but not mild iodine deficiency, is a determinant of serum fT4 and T4 in pregnant women. Correcting iron deficiency may help to maintain optimal thyroid function, in addition to preventing anemia during pregnancy.

Iodine deficiency in pregnant women and newborns in the Saratov region: current state of the problem

Introduction. Iodine deficiency remains an urgent challenge for the Russian Federation. Pregnant women should receive prophylactic potassium iodide supplements at a dose of 200–250 mcg per day. To monitor the severity of iodine deficiency in the regions and the efficacy of prenatal iodine prophylaxis, it is prudent to use the neonatal hyperthyrotropinemia rate for newborns (thyroidstimulating hormone level is higher than 5 μIU/L) based on the results of congenital hypothyroidism screening.Objective. To assess the changes in the severity of iodine deficiency and the efficacy of iodine prophylaxis in pregnant women and newborns in the Saratov region based on the incidence of neonatal hyperthyrotropinemia over the past 25 years.Materials and methods. The incidence of neonatal hyperthyrotropinemia in newborns in the Saratov region for the period of 1996–2000 and 2015–2020 was analysed. In total, 229,625 children were examined.Results and discussion. In 1996–2000, neonatal hyperthyrotropinemia was detected in 37.4% of newborns, which was evidence of the presence of moderate iodine deficiency in the region. In 2015–2020, the incidence of neonatal hyperthyrotropinemia decreased by 5.42 times to 6.9% (p &lt; 0.0001) against the background of group iodine prophylaxis in pregnant women, but remained higher than the World Health Organization targets for iodine-rich regions (&lt;3%) suggesting the preservation of mild iodine deficiency in pregnant women and newborns in the Saratov region.Conclusions. Despite the obligatory doctor’s prescription of prenatal group iodine prophylaxis, there is still iodine insufficiency in pregnant women and newborns in the Saratov region, which requires further improvement of the regional iodine deficiency eradication action system in the risk groups. However, significant advances in the fight against iodine deficiency in the nutrition of the Russian population can only be achieved after the adoption of the federal law on universal salt iodization.

Prevalence of insufficient iodine intake in pregnancy worldwide: a systematic review and meta-analysis.

Iodine deficiency in pregnant women is related to impaired foetal growth and development. The objective of this study was to estimate the prevalence of insufficient iodine intake in pregnant women from different regions of the world. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, five electronic databases and Google Scholar grey literature were searched until 10 April 2021. Two reviewers independently conducted article selection, data extraction, and assessment of the risk of bias. Meta-analyses with random effects, subgroup analyses, and meta-regressions were performed. In total, 4639 observational articles were found, with 61 eligible for inclusion. The population consisted of 163,021 pregnant women adults and adolescents, and the overall prevalence of insufficient iodine intake was 53% (95% confidence interval [CI]: 47-60; I2 = 99.8%). Pregnant women who live in insufficient iodine status country had a higher prevalence (86%; 95% CI: 78-93; I² =97.0%) of inadequate iodine nutritional status than to those living in country considered sufficient (51%; 95% IC: 45-57; I² = 99.8%). Despite the progress in iodine fortification policies and periodic monitoring of the iodine nutritional status of the population worldwide, salt iodination alone may not be sufficient to provide adequate iodine status to pregnant women. Thus, other actions may be necessary to improve the nutritional clinical care of pregnant group.

Біологічна роль йоду та йодна недостатність як патогенетичний фактор виникнення тиреоїдної патології у вагітних та її профілактика

У статті знайшли відображення найбільш важливі наукові відомості про значення йоду в біологічній природі, його участь у різноманітних біологічних процесах, в утворенні тиреоїдних гормонів та реалізації їх ефектів на рівні різних органів і клітин, що пояснюють виникнення йодозалежних захворювань. Значна увага в статті приділяється ролі йоду в синтезі тиреоїдних гормонів при вагітності та з’ясуванню причин підвищеної потреби в цьому елементі при даному стані. Проведений аналіз результатів багаторічних епідеміологічних досліджень, спрямованих на вивчення йодного забезпечення вагітних у різних регіонах України, співробітниками відділу епідеміології ендокринних захворювань ДУ «Інститут ендокринології та обміну речовин ім. В.П. Комісаренка НАМН України». Значна кількість цих досліджень виконана за підтримки МОЗ України, Дитячого фонду ЮНІСЕФ в Україні, а також центру СDC в Атланті (США), який протягом понад 15 років здійснював контроль за якістю досліджень одного з найважливіших показників йодного статусу населення України — йодурії. Стаття підготовлена як науковий інформаційний матеріал для ендокринологів, акушерів-гінекологів, гігієністів, сімейних лікарів, громадськості, МОЗ України у зв’язку з необхідністю законодавчого вирішення проблеми профілактики йодозалежних захворювань в Україні.

ASSESSMENT OF URINARY IODINE LEVEL AND ITS RELATION TO THYROID FUNCTION IN SAMPLE OF EGYPTIAN PREGNANT FEMALES IN 1ST TRIMESTER

Background: Thyroid disorders are considered the second most common endocrine disorders affecting women during their reproductive years and can impact up to 4% of all pregnancies. Of all thyroid disorders, hypothyroidism is the most prevalent, impacting approximately 2- 3% of all pregnancies. Hyperthyroidism is far less prevalent, impacting approximately 0.2% of all pregnancies.Aim of the Work: To assess the level of urinary iodine in 1st trimester of pregnancy and its relation with thyroid hormones level and autoimmunity status.Subjects and Methods: To elucidate this aim 100 healthy pregnant female in their 1st trimester of pregnancy were included in the study. They were collected from Obstetrics and Gynecology Department El Demerdash hospital and Dar El shefa Hospital in the period from September, 2020 to November, 2020.Results: Median urinary iodine was 55(41.0-76.0) μg/l and their was99 females had insufficient iodine intake less than 150μg /l, one had adequate intake (150-249) μg /l and none showed more than necessary intake (250-499) μg /l or excessive intake more than 500 μg /l. As regard thyroid ultrasound there was normal Thyroid volume in 94 subjects,(94.0%)., increased volume in 6 subjects (6%). There was a Significant negative correlation between each of the following the age and the gestational age; and urinary iodineConclusion: There was a significant iodine deficiency in pregnant women within the study area, indicating that some women may need to increase their iodine intake during pregnancy. Additionally, diagnosis and treatment of thyroid dysfunction during pregnancy should be based on pregnancy and method specific reference intervals, and more detailed staging is needed to assess pregnant women's thyroid function.

Iodine knowledge is associated with iodine status in Portuguese pregnant women: results from the IoMum cohort study.

Lack of knowledge about iodine has been suggested as a risk factor for iodine deficiency in pregnant women, but no studies have addressed this issue in Portugal. So, the aim of this study was to investigate iodine knowledge among Portuguese pregnant women and its association with iodine status. IoMum, a prospective observational study, included 485 pregnant women recruited at Centro Hospitalar e Universitário de S. João, Porto, between the 10th and 13th gestational weeks. Partial scores for knowledge on iodine importance, on iodine food sources or on iodised salt were obtained through the application of a structured questionnaire. Then, a total iodine knowledge score was calculated and grouped into low, medium and high knowledge categories. Urinary iodine concentration (UIC) was measured in spot urine samples by inductively coupled plasma MS. Of the pregnant women, 54 % correctly recognised iodine as important to neurocognitive development, 32 % were unable to identify any iodine-rich food and 71 % presented lack of knowledge regarding iodised salt. Of the women, 61 % had a medium total score of iodine knowledge. Knowledge on iodine importance during pregnancy was positively associated with iodine supplementation and also with UIC. Nevertheless, median UIC in women who correctly recognised the importance of iodine was below the cut-off for adequacy in pregnancy (150 µg/l). In conclusion, knowledge on iodine importance is positively associated with iodine status. Despite this, recognising iodine importance during pregnancy may not be sufficient to ensure iodine adequacy. Literacy-promoting actions are urgently needed to improve iodine status in pregnancy.

The Status and Knowledge of Iodine among Pregnant Women in Shanghai.

Iodine plays an important role in thyroid function. However, in daily practices, people lack the related details including the knowledge concerned iodine usage, attitudes towards it, and practice among pregnant women. The aim of the present study is to assess the iodine status of pregnant women in Shanghai, and their knowledge regarding iodine, with the goal of investigating the relationship between iodine and thyroid function during pregnancy. This is a cross-sectional study. We recruited 3 groups of participants including 145 pregnant women (12-16weeks gestation), 101 pregnant women (24-28weeks gestation), and 108 pregnant women (34-38weeks gestation). Iodine status and dietary intake were calculated from 24-h urinary iodine concentration (UIC). Knowledge regarding iodine was collected through a questionnaire. We additionally examined TSH, FT3, FT4, and TPOAb of the participants. The median of UIC of the 354 pregnant women was 119.2μg/L, and 68.9% had urinary iodine levels below 150μg/L. The proportion of daily iodized salt consumption in pregnant women was only 78.0%. The median UIC of the pregnant women who had consumed iodized salt was significantly higher than that of the pregnant women without iodized salt intake (Z = - 5.087, P < 0.001). Pregnant women in weeks 34-38 with a high level of knowledge had significantly lower TSH levels than those with low knowledge level (P = 0.046). Among the 349 pregnant women, few were aware of the harm to the fetus (8.3%). Significant differences were found in the scores for the knowledge level of women with different educational levels (Z = - 5.413, P < 0.001). Pregnant women in Shanghai have mild iodine deficiency. Approaches to improve iodine status among pregnant women in Shanghai include raising their awareness of iodine intake and changing their dietary habits. Otherwise, the risk of iodine deficiency in pregnant women may continue to increase.

Iodine deficiency in pregnant women on São Miguel Island, Azores. Assessing the Impact of Corrective Measures

Iodine deficiency in pregnant women on São Miguel Island, Azores. Assessing the Impact of Corrective Measures

Adequately iodized salt is an important strategy to prevent iodine insufficiency in pregnant women living in Central Java, Indonesia.

Iodine is an essential micronutrient for cognitive development and growth. Optimal intakes are critical during pregnancy. We report the iodine status and thyroid function of pregnant women living in areas previously affected by severe iodine deficiency and in longstanding iodine sufficient areas in Java, Indonesia. This cross-sectional study was conducted in Magelang, Java, from July to November 2015, in four sub-districts; two previously affected by severe iodine deficiency (area 1) and two that were iodine-sufficient (area 2). Iodine intake was estimated using median urinary iodine concentration in spot samples and mean urinary iodine excretion in 3 x 24-hour samples, thyroid hormones (thyroid-stimulating hormone and free thyroxine) were measured in venous blood samples, and iodine content of household salt samples was estimated by titration. We recruited a total of 244 pregnant women, 123 in area 1 and 121 in area 2. Urinary iodine results suggested adequate habitual iodine intakes in both areas (median urinary iodine concentration in area 1: 222 μg/l (interquartile range 189, 276 μg/l), area 2: 264 μg/l (interquartile range 172, 284 μg/l), however, the risk of inadequate intakes increased with advancing trimester (Odds Ratio = 2.59 (95% CI 1.19–5.67) and 3.85 (95% CI 1.64–9.02) at second and third trimesters, respectively). Estimated prevalence of thyroid function disorders was generally low. Salt was iodized to approximately 40 ppm and foods rich in native iodine did not contribute significantly to dietary intakes. Adequately iodized salt continues to prevent iodine insufficiency in pregnant women living in areas previously affected by severe iodine deficiency in Java, Indonesia. Monitoring and surveillance, particularly in vulnerable groups, should be emphasized to ensure iodine sufficiency prevails.

Association of iodine-related knowledge, attitudes and behaviours with urinary iodine excretion in pregnant women with mild iodine deficiency.

Subsequent to the implementation of the universal salt iodisation policy, China has all but eliminated the iodine deficiency disorders. However, pregnant women are still experiencing mild iodine deficiency. The present study explored factors that could relate to mild iodine deficiency in pregnant women. In total, 2400 pregnant women were enrolled using a multistage, stratified, random sampling method in Shanghai. Data were collected via a standardised questionnaire. The urine samples and household cooking salt samples were collected for the detection of urinary iodine and salt iodine concentrations. The median urinary iodine concentration (MUIC) was 148.0μg L-1 for all participants, and 155.0μg L-1 , 151.0μg L-1 and 139.6μg L-1 in the first, second and third trimesters. The MUIC in the third trimester was significantly lower than that of the first trimester (P<0.05). The usage rates of iodised salt and qualified-iodised salt were 71.5% and 59.4%, respectively. Iodine-related knowledge score composition ratio was significantly different between the high and low UIC groups (P<0.05). Participants' MUIC increased significantly with the increases in iodine-related knowledge score (P<0.001). The third trimester was a significant risk factor for high UIC, whereas high iodine-related knowledge score, actively learning dietary knowledge and having a habit of consuming iodine-rich food were significant protective factors for high UIC (P<0.05). Iodine level is adequate among pregnant women in Shanghai during the first and the second trimesters, although it is is insufficient in the third trimester. Good iodine-related knowledge, attitudes and behaviours are important for pregnant women with respect to maintaining adequate urinary iodine.

Impact of iodine supplementation during preconception, pregnancy and lactation on maternal thyroid homeostasis and offspring psychomotor development: protocol of the IodineMinho prospective study

BackgroundIodine deficiency is the most common cause of preventable brain harm and cognitive impairment in children. Portuguese women of childbearing age, pregnant women and their progeny were shown to have inadequate iodine intake. Consequently, the Portuguese Health Authorities have recommended a daily supplementation with 150–200 µg iodine in preconception, pregnancy, and lactation. The IodineMinho study intends to evaluate whether (i) this recommendation impacted on the prevalence of iodine deficiency in pregnant women from the Minho region of Portugal, (ii) the time of initiation of iodine supplementation (if any) influences the serum levels of thyroid hormones at several intervals during pregnancy and (iii) there are serum thyroid-hormone parameters in the 1st trimester of pregnancy that predict psychomotor development of the child at 18 months of age.MethodsMost Portuguese women are followed throughout pregnancy in community Family Health Units, where family physicians may choose to follow the National recommendation or other, concerning iodine sufficiency. This study will recruit women (N = 304) who intend to become pregnant or are already pregnant from 10 representative Units. Physician’s approach and prescriptions, sociodemographic, nutrition and clinical information will be obtained at baseline and throughout pregnancy. To evaluate endocrine function, blood and urine samples will be collected at recruitment, once in each trimester of pregnancy, at delivery and 3 months after delivery. Breastmilk samples will be collected for iodine and energy content analysis. Children will be evaluated for psychomotor development at 18 months. Maternal thyroid volume will be evaluated by ultrasound scan at baseline, in the 3rd trimester and at 3 months after delivery.DiscussionIodine deficiency early during development precludes children from achieving full intellectual capabilities. This protocol describes a study that is innovative and unique in its detailed and comprehensive evaluation of maternal and child endocrine and psychomotor parameters. By evaluating the effectiveness of the iodine supplementation recommendation, it will contribute to the public health systems’ efforts to provide excellence in maternal and infant care.Trial registrationClinicalTrials.gov, NCT04288531. Registered 28 February 2020-Retrospectively registered.

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.

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.

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.