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Severe iodine deficiency in mothers is known to impair foetal development. Pregnant women in the UK may be iodine insufficient, but recent assessments of iodine status are limited. This study assessed maternal urinary iodine concentrations (UIC) and birth outcomes in three UK cities. Spot urines were collected from 541 women in London, Manchester a...
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Context 1
... mean UIC varied by marital status, geographical location, neonatal gestational age at delivery and gestational time point (Table 2). UIC also varied across time points, with the 20 week concentrations being on average lower than the 15-week concentrations. ...
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Severe iodine deficiency in mothers is known to impair foetal development. Pregnant women in the UK may be iodine insufficient, but recent assessments of iodine status are limited. This study assessed maternal urinary iodine concentrations (UIC) and birth outcomes in three UK cities. Spot urines were collected from 541 women in London, Manchester a...
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Citations
... Iodine, as an essential elementary microelement, is vitally important to maintain euthyroid function of pregnant women and their infants [1] , especially in the rst 1000 days of life, the critical period of growth and development [2] . Severe iodine de ciency during pregnancy can cause the thyroid dysfunction of neonates, adverse obstetric outcomes such as abortion and stillbirth, even lead to congenital cretinism, which expressed as physical and mental retardation [3,4] . Adequate nutritional iodine support in the rst 1,000 days of life not only provides a good short-term health bene t, but also affects long-term health [2] . ...
... A study in Spanish found that mean birth weight in infants with iodine de ciency during pregnancy was signi cantly lower, compared with those in the iodine-su cient group [13] . Other studies conducted in iodized-salt covered regions showed although maternal UIC during pregnancy indicative iodine de ciency, no association was found between UIC and birth weight [4,15] . ...
... In terms to the relationship of other factors on neonatal birth weight, such as delivery week and delivery way, and infants' gender, consistent with most studies [18,19,27] . And higher birth weight was found in multiparous women [28] , while different results [4,15] were still found in other study design in infants exposed various iodine nutrition. Above differences probably were due to varied participants and research methods, which likely result in different neonatal outcomes and different UIC distribution. ...
Background: The impact of mild to moderate iodine deficiency is still controversial. We aimed to explore the effects of mild-to-moderate iodine deficiency during pregnancy on neonatal physical growth and TSH.
Methods: 2613 pregnant women and their infants were enrolled in this prospective cohort study. Spot urine and venous blood samples were collected to determine urinary iodine concentration (UIC) and thyroid-stimulating hormone (TSH). Heel blood samples of neonates were collected within 72 hours after birth to determine neonatal TSH.
Results: The median UIC was 116 (64, 190) μg/L and 63.9% of pregnant women had UIC < 150μg/L, indicating mild-to-moderate iodine deficiency. Lower birth weight and WFA Z-scoreswere found in neonates with maternal UIC ranged 100-149μg/L during pregnancy(both P < 0.05), and were associated with parity (0 or ≥ 1), delivery week (< 37wks or ≥ 37wks) and delivery way (all P < 0.05). 40.4% neonates had TSH ≥ 5.0mIU/L. Neonatal TSH increased by 0.28mIU/L per unit in neonates with nulliparous mother than multiparous, 1.12mIU/L higher in term neonates than preterm and 0.44mIU/L higher in neonates born via NVD than CS (all P < 0.05), respectively. The rate of neonatal TSH ≥ 5.0mIU/L was 1.103 folds positively associated with Maternal TSH and 1.178 times higher related to parity equals 0, 2.485 times higher in term neonates than preterm and 1.444 times higher in neonates born via NVD than CS (all P<0.05).
Conclusions: The iodine nutrition in pregnant women in Shunde was mild-to-moderate deficient. Lower birth weight and WFA Z-scores in neonates were related to maternal UIC within 100-149μg/L.BMI of pregnant women, parity, neonatal gender, delivery week and way affected neonatal birth weight and WFA Z-scores. High maternal TSH led to high neonatal TSH. Maternal age, parity, delivery week and way had effects on neonatal TSH and neonatal TSH ≥ 5.0mIU/L.
... The thyroid hormone will stop acting if its iodine requirements are not met. Low thyroid hormone levels in the blood caused a slew of functional and developmental problems known as iodine deficiency disorder (IDDs) (Snart et al., 2019). The universal fortification of salt with iodine is one technique to treat iodine deficiency disorder (IDD). ...
Background: Even though iodine is not an essential micronutrient for the plant, it is very much needed for a person's mental and physical development. Due to the presence of negative charge on iodine it is highly susceptible to leaching. Further iodine is also highly prone to volatilization loss due to biochemical and physiochemical properties of soil leading to iodine deficiency. Agronomic biofortification of iodine is one of the ways to address iodine deficiency globally. Numerous studies have focused on the process by which plants absorb iodine from the soil, but there is still paucity of knowledge on stability of biofortified iodine in fruits. Methods: In our work, we assessed iodine bioavailability (Cooking, soaking and digestion) in tomato fruit from different sources of chitosan and potassium iodate alone and combinations using main and residual crop trials. The field experiment was carried out in Thondamuthur block of Viraliyur village at Coimbatore district of Tamil Nadu in 2021. Potassium iodate and chitosan were applied in the form of soil, foliar, and chitosan iodate complex at different stages of plant growth. Results: The results suggested that combination and potassium iodate and chitosan complex has increased the iodine stability in fruits of main crop and also retained the iodine in residual crop. As electrostatic interaction between chitosan and iodate prevents volatilization and gradually stabilizes the bioavailability of iodine in fruits. Our findings offer more details on iodine mobility and behaviour in fruits when it is used alone and combination with chitosan at different rates
... Spanish women with mildly insufficient iodine intakes in the third trimester were 13% less likely to have an infant small for gestational age than women with severe iodine deficiency [63], and in England, a trend for SGA or low-birthweight infants with iodine deficiency has been observed across several studies [64,65]. However, results are equivocal [66,67]. Our systematic review found no effect of iodine supplementation on infant length at birth [59]. ...
Iodine is an essential micronutrient and component of thyroid hormone. An adequate dietary iodine intake is critical to maintain and promote normal growth and development, especially during vulnerable life stages such as pregnancy and early infancy. The role of iodine in cognitive development is supported by numerous interventional and observational studies, and when iodine intake is too low, somatic growth is also impaired. This can be clearly seen in cases of untreated congenital hypothyroidism related to severe iodine deficiency, which is characterized, in part, by a short stature. Nevertheless, the impact of a less severe iodine deficiency on growth, whether in utero or postnatal, is unclear. Robust studies examining the relationship between iodine and growth are rarely feasible, including the aspect of examining the effect of a single micronutrient on a process that is reliant on multiple nutrients for optimal success. Conversely, excessive iodine intake can affect thyroid function and the secretion of optimal thyroid hormone levels; however, whether this affects growth has not been examined. This narrative review outlines the mechanisms by which iodine contributes to the growth process from conception onwards, supported by evidence from human studies. It emphasizes the need for adequate iodine public health policies and their robust monitoring and surveillance, to ensure coverage for all population groups, particularly those at life stages vulnerable for growth. Finally, it summarizes the other micronutrients important to consider alongside iodine when seeking to assess the impact of iodine on somatic growth.
... Two recent systematic reviews of observational studies of iodine and birth outcomes drew differing conclusions [9,10]. Since these reviews were published, results on iodine and birth outcomes from a number of large birth cohorts have become available, including the Norwegian Mother and Child Cohort Study (MoBa) [11], the Screening for Pregnancy Endpoints (SCOPE) cohort [12], the Born in Bradford (BiB) cohort [13], and results from the Shanghai birth registry [14]. There is potential for studies in deficient populations to draw substantially different conclusions from those in less-deficient populations, and for effects to only be seen in individuals with particularly poor intakes. ...
... 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. ...
... 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]. ...
Background & aims:
Iodine is important for thyroid function during pregnancy to support fetal growth, but studies of maternal iodine status and birth outcomes are conflicting. We aimed to quantify the association between iodine status and birth outcomes, including potential threshold effects using nonlinear dose-response curves.
Methods:
We systematically searched Medline and Embase to 10 October 2022 for relevant cohort studies. We conducted random-effects meta-analyses of urinary iodine concentration (UIC), iodine:creatinine ratio (I:Cr), and iodide intake for associations with birth weight, birth weight centile, small for gestational age (SGA), preterm delivery, and other birth outcomes. Study quality was assessed using the Newcastle-Ottawa scale.
Results:
Meta-analyses were conducted on 23 cohorts with 42269 participants. Birth weight was similar between UIC ≥ 150 μg/L and <150 μg/L (difference = 30 g, 95% CI -22 to 83, p = 0.3, n = 13, I2 = 89%) with no evidence of linear trend (4 g per 50 μg/L, -3 to 10, p = 0.2, n = 12, I2 = 80%). I:Cr was similar, but with nonlinear trend suggesting I:Cr up to 200 μg/g associated with increasing birthweight (p = 0.02, n = 5). Birthweight was 2.0 centiles (0.3 to 3.7, p = 0.02, n = 4, I2 = 0%) higher with UIC ≥ 150 μg/g, but not for I:Cr. UIC ≥ 150 μg/L was associated with lower risk of SGA (RR = 0.85, 0.75 to 0.96, p = 0.01, n = 13, I2 = 0%), but not with I:Cr.
Conclusions:
The main risk of bias was adjustment for confounding, with variation in urine sample collection and exposure definition. There were modest-sized associations between some measures of iodine status, birth weight, birth weight centile, and SGA. In pregnancy, we recommend that future studies report standardised measures of birth weight that take account of gestational age, such as birth weight centile and SGA. Whilst associations were modest-sized, we recommend maintaining iodine sufficiency in the population, especially for women of childbearing age on restricted diets low in iodide.
... 14 In London, Manchester, and Leeds, the median urinary iodine concentration in pregnant women was also below 150 mcg/l, showing the insufficiency of iodine intake for this particular population, even though the United Kingdom's population is generally considered iodine sufficient. 21 This way, the last guidelines from the American Thyroid Association, Endocrine Society, and European Thyroid Association, recommend the administration of iodine supplements to pregnant women and those planning to get pregnant. [3][4][5] Brazilian data on iodine sufficiency in pregnant women are controversial. ...
Objective To evaluate the iodine sufficiency of pregnant women assisted in a University Hospital of Minas Gerais, and to correlate the urinary concentrations of maternal iodine with the fetal thyroid hormone levels at birth.
Methods Urinary iodine concentrations from 30 pregnant women with a singleton pregnancy and gestational age lower than 20 weeks were analyzed. Occasional samples of the mothers' urine were collected for the urinary iodine concentration dosage, and these were correlated with the newborns' thyroid-stimulating hormone (TSH) levels.
Results The median iodine urinary concentration of this study's pregnant women population was 216.73 mcg/l, which is proper for the group, following the World Health Organization (WHO). No cases of neonatal hypothyroidism were reported in the study, which corroborates the iodine sufficiency in this population sample.
Conclusion This study shows that despite the increased demand for iodine from pregnant women and the Brazilian Health Regulatory Agency (ANVISA) recommendation of 2013 for reduction of salt iodization levels, the population of pregnant women attended in the prenatal ambulatory of normal risk from the Federal University of Minas Gerais is considered sufficient in iodine. As a higher sample is necessary for the confirmation of these findings, it is too early to recommend the universal supplementation of iodine for Brazilian pregnant women, and more studies must be carried out, considering that iodine supplementation for pregnant women in an area of iodine sufficiency is associated to the risks of the fetus's excessive exposure to iodine.
... Although iodine excess has low morbidity during pregnancy, it can also cause adverse pregnancy outcomes [5]. In contrast, some studies reported that an abnormal iodine status is not associated with an adverse pregnancy outcome [6,7]. However, iodine is essential for fetal growth and brain development. ...
... A populationbased prospective cohort study found that iodine deficiency, even moderate-to-severe iodine deficiency, did not increase the risk of abortion [7]. A study of maternal UI and pregnancy outcomes in three British cities found that the iodine nutritional status was not associated with birth weight and natural preterm delivery [6]. A meta-analysis of UI in pregnant women with normal thyroid function and pregnancy outcomes showed that the iodine nutritional status was not associated with preterm delivery, low birth weight, HDP, and neonatal birth characteristics [9]. ...
Iodine is an essential trace element for humans and the main raw material for thyroid hormone synthesis. However, the association between iodine nutritional status and adverse pregnancy outcomes in different regions remains controversial. This single-center cohort study was focused on the association between iodine nutritional status and adverse pregnancy outcomes in Beijing, China. We enrolled 726 pregnant women who were registered at the Peking University International Hospital between February 2017 and December 2019. To analyze the association between iodine nutritional status variations and adverse pregnancy outcomes, this study cohort included 390 (53.72%) participants with iodine deficiency, 206 (28.37%) with an adequate iodine level, 103 (14.19%) with a more than adequate iodine level, and 27 (3.72%) with iodine excess, according to the urinary iodine (UI) status of pregnant women. After adjusting for age, body mass index, parity, and history of spontaneous abortion, we identified iodine deficiency as a risk factor for anti-thyroid peroxidase antibody (TPOAb) positivity [odds ratio (OR), 3.646; 95% confidence interval (95% CI), 1.658–8.017], anti-thyroglobulin antibody (TGAb) positivity (OR, 3.109; 95% CI, 1.465–6.599), and thyroid autoimmunity (OR, 2.885; 95% CI, 1.539–5.407). There was a non-linear relationship between UI and the concentrations of TPOAb and TGAb ( P non-linear < 0.05). Iodine deficiency during the first trimester is a risk factor for thyroid autoantibody positivity. The relationship between UI and the concentrations of TPOAb and TGAb follows a nearly U-shaped curve. Thus, physicians should critically consider the iodine nutritional status of pregnant women during the first trimester. Clinical Trials.gov Identifier: NCT02966405
... A prospective study including 541 pregnant women was conducted in London, Leeds, and Manchester between 2004 and 2008 (Snart et al., 2019). The median UIC was 134 µg/L and was between 100 and 150 in all three cities. ...
Excessive salt intake is a risk factor for noncommunicable diseases, but salt iodization is the most effective method of population-based prevention of iodine deficiency. Therefore, an assessment of dietary iodine intake from the use of iodized salt in the food industry and potential reductions in salt intake is needed. Objective. To assess the feasibility of integrating iodine deficiency prevention and salt reduction programmes among the adult population in the Republic of Belarus. Material and methods. Using the thiocyanate-nitrite method, the determination of iodine in various types of foods was carried out. Taking into account the actual dietary intake, estimated using the frequency method among 583 respondents over 18 years old, living in Minsk, from various socioeconomic groups, alimentary iodine intake was assessed at different levels of salt use in households. The level of iodine sufficiency was additionally estimated on the base of urinary excretion data obtained by the cerium-arsenite spectrophotometric method in 100 healthy adults over the age of 18 living in Minsk (65 women and 35 men). Results. As part of the legal framework for the use of iodized salt in food production, there has been a steady increase in iodine levels in the target products (bakery and meat products to 42.0 and 133.3 μg/100 g respectively). The content of the discussed micronutrient in the diet of the adult population has raised at least 1.9-fold in recent decades, to 237.3 μg/day in the most realistic consumption model. The main source of iodine among this subpopulation is commercially produced foods with iodized salt, which forms 30-58% of the alimentary iodine exposure. Consumption of salt in Belarus averages 10.6 g per day, which poses a risk of developing noncommunicable diseases and necessitates programmes to reduce the level of salt in the diet. Modeling of scenarios with reduction of salt use in households in accordance with the recommendations of the World Health Organization (WHO) shows that the main contribution to dietary iodine exposure will be made by bread products (38%), about 1/3 will be formed by table salt, the value of non-target fortified products (milk and eggs) will increase (up to 21%). The contribution of table iodized salt to the dietary iodine exposure reaches 43% at actual consumption levels and will decrease to 18% if it is reduced to the WHO recommended values. The median of ioduria among those surveyed is 136.8 μg/l, indicating adequate iodine supply. Conclusion. In implementing joint programs on prevention of iodine deficiency and cardiovascular diseases associated with excessive salt intake, it is necessary to consider national conditions - mandatory use of iodized salt in food industry, its level of fortification, content of this micronutrient in foodstuffs and structure of their consumption among certain population groups.
... In recent years, several studies have assessed UIC in pregnant women. Most of them showed low median UIC, suggesting insufficient iodine status in pregnancy [25,[41][42][43][44][45][46][47][48]. ...
Iodine is an essential component for fetal neurodevelopment and maternal thyroid function. Urine iodine is the most widely used indicator of iodine status. In this study, a novel validated ion-pair HPLC–UV method was developed to measure iodine concentration in clinical samples. A sodium thiosulfate solution was added to the urine sample to convert the total free iodine to iodide. Chromatographic separation was achieved in a Pursuit XRs C8 column. The mobile phase consisted of acetonitrile and a water phase containing 18-crown-6-ether, octylamine and sodium dihydrogen phosphate. Validation parameters, such as accuracy, precision, limits of detection and quantification, linearity and stability, were determined. Urinary samples from pregnant women were used to complete the validation and confirm the method’s applicability. In the studied population of 93 pregnant women, the median UIC was lower in the group without iodine supplementation (117 µg/L, confidence interval (%CI): 95; 138) than in the supplement group (133 µg/L, %CI: 109; 157). In conclusion, the newly established ion-pair HPLC–UV method was adequately precise, accurate and fulfilled validation the criteria for analyzing compounds in biological fluids. The method is less complicated and expensive than other frequently used assays and permits the identification of the iodine-deficient subjects.
... There is a general consensus on the importance of treating hypothyroidism early in pregnancy to prevent complications [20]. Despite the fact that a relationship has been confirmed between subclinical hypothyroidism and hypothyroxinemia with obstetric difficulties and fetal psychomotor and neurocognitive impairment [21][22][23][24][25][26], there is still no clear evidence of the positive effects of thyroxine treatment in these cases [27,28]. ...
Iodine is an essential micronutrient for the synthesis of thyroid hormones. The proper functioning of the thyroid axis is essential for the normal development of the nervous system, especially in the first trimester of gestation. The aim of the present study was to analyze the perinatal outcomes, anthropometry, and APGAR test scores of newborns and to relate them to maternal thyroid status. A total of 190 newborns participated in the study. No correlation was found between thyroid stimulating hormone (TSH) and maternal ioduria values in the first trimester of gestation with the weight or length of the newborn, or the APGAR score at one minute after birth. However, we found significant differences between the APGAR scores of children whose mothers had an iodine sufficiency level in the first trimester compared to the children of mothers with iodine deficiency. Similarly, the APGAR scores of children whose mothers had a TSH > 4 have significantly better APGAR scores than the children of mothers with a TSH < 4. Likewise, we found significant differences between the measurements of the newborns depending on whether their mothers smoked. The children of mothers who took iodine supplements or iodized salt obtained the highest APGAR score at one and five minutes after birth. It is essential to focus on recommending adequate consumption of iodine supplements and iodized salt prior to gestation and at least during the first trimester to achieve better fetal well-being.
... However, less is known about any consequences for fetal development of mild or moderate deficiency. Associations with smaller birthweight [4][5][6], preterm birth [5] and child neurodevelopment [7][8][9] have been observed in mildly or moderately deficient populations, but evidence is inconsistent, with other large studies reporting no evidence of associations [10][11][12][13]. ...
... Since iodine demand increases in pregnancy, there is more general concern about the iodine status of UK women of reproductive age [1]. Whilst some recent studies report urinary iodine status in pregnant populations [11,23,24], few have examined how iodide intake and urinary iodine status vary across different trimesters and postpartum and how these relate to thyroid function. ...
... A standard Jaffe reaction-based microplate assay was used to evaluate urinary creatinine concentrations. Detailed methods for urinary iodine and creatinine measurement have been described previously [11]. ...
Iodine is essential for normal thyroid function, supporting healthy fetal and child development. Io-dine requirements increase in pregnancy, but many women in regions without salt iodisation have insufficient intakes. We explored associations between iodide intake and urinary iodine concentra-tion (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. 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-hour re-calls. During pregnancy, median (IQR) dietary iodide intake was 101µg/day (54, 142), with 42% from dairy and 9% white fish. Including supplements, intake was 143µg/day (94, 196), with 49% < UK reference nutrient intake (140µg/day). Women with Pakistani heritage had 129µg/day (87, 190) median total intake. Total intake during pregnancy was associated with 4% (95% CI: 1%, 7%) high-er UIC, 5% (3%, 7%) higher I:Cr, 4% (2%, 6%) lower thyroglobulin and 21% (9%, 32%) lower odds of palpable goiter per 50µg/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.
