Does Iodine Intake Modify the Effect of Maternal Dysglycemia on Birth Weight in Mild-to-Moderate Iodine-Deficient Populations? A Mother-Newborn Prospective Cohort Study.

It is unclear how maternal glycemic status and maternal iodine status influence birth weight among individuals with mild-to-moderate iodine deficiency (ID). We studied the association between birth weight and both maternal glucose levels and iodine intake among pregnant women with mild-to-moderate ID. Glucose values were assessed using a glucose challenge test (GCT) and non-fasting glucose levels that were determined before delivery; individuals' iodine statuses were assessed using an iodine food frequency questionnaire; and serum thyroglobulin (Tg) and urinary iodine concentrations (UIC) were used to assess each group's iodine status. Thyroid antibodies and free thyroxine (FT4) levels were measured. Obstetric and anthropometric data were also collected. Large-for-gestational age (LGA) status was predicted using a Cox proportional hazards model with multiple confounders. Tg > 13 g/L was independently associated with LGA (adjusted hazard ratio = 3.4, 95% CI: 1.4-10.2, p = 0.001). Estimated iodine intake correlated with FT4 among participants who reported consuming iodine-containing supplements (ICS) after adjusting for confounders (ß = 0.4, 95% CI: 0.0002-0.0008, p = 0.001). Newborn weight percentiles were inversely correlated with maternal FT4 values (ß = -0.2 95% CI:-0.08--56.49, p = 0.049). We conclude that in mild-to-moderate ID regions, insufficient maternal iodine status may increase LGA risk. Iodine status and ICS intake may modify the effect that maternal dysglycemia has on offspring weight.

Prenatal exposure to heavy metal mixtures and anthropometric birth outcomes: a cross-sectional study.

BACKGROUND: Numerous studies have suggested significant associations between prenatal exposure to heavy metals and newborn anthropometric measures. However, little is known about the effect of various heavy metal mixtures at relatively low concentrations. Hence, this study aimed to investigate associations between prenatal exposures to a wide range of individual heavy metals and heavy metal mixtures with anthropometric measures of newborns. METHODS: We recruited 975 mother-term infant pairs from two major hospitals in Israel. Associations between eight heavy metals (arsenic, cadmium, chromium, mercury, nickel, lead, selenium, and thallium) detected in maternal urine samples on the day of delivery with weight, length, and head circumference at birth were estimated using linear and Bayesian kernel machine regression (BKMR) models. RESULTS: Most heavy metals examined in our study were observed in lower concentrations than in other studies, except for selenium. In the linear as well as the BKMR models, birth weight and length were negatively associated with levels of chromium. Birth weight was found to be negatively associated with thallium and positively associated with nickel. CONCLUSION: By using a large sample size and advanced statistical models, we could examine the association between prenatal exposure to metals in relatively low concentrations and anthropometric measures of newborns. Chromium was suggested to be the most influential metal in the mixture, and its associations with birth weight and length were found negative. Head circumference was neither associated with any of the metals, yet the levels of metals detected in our sample were relatively low. The suggested associations should be further investigated and could shed light on complex biochemical processes involved in intrauterine fetal development.

Can Mild-to-Moderate Iodine Deficiency during Pregnancy Alter Thyroid Function? Lessons from a Mother-Newborn Cohort.

Severe iodine deficiency during pregnancy has substantial hormonal consequences, such as fetal brain damage. Data on the potential effects of mild-to-moderate iodine deficiency on the thyroid function of pregnant women and their newborns are scarce and divergent. We investigated the association between iodine intake in pregnancy and maternal and neonatal thyroid function in a region with mild-to-moderate iodine deficiency. Pregnant women's iodine status was evaluated using an iodine food frequency questionnaire, serum thyroglobulin (Tg), and urinary iodine concentration (UIC). Neonatal thyrotropin (nTSH) values were measured after birth. Obstetrics and anthropometric data were also collected. Among the 178 women (median age 31 years) included in the study, median (interquartile range) estimated dietary iodine intake, Tg and UIC were 179 (94−268) µg/day, 18 (11−33) µg/L, and 60 (41−95) µg/L, respectively. There was a significant inverse association of iodine intake with Tg values among the study population (ß = −0.2, F = 7.5, p < 0.01). Women with high free triiodothyronine (FT3) values were more likely to exhibit an estimated iodine intake below the estimated average requirement (160 µg/day, odds ratio [OR] = 2.6; 95% confidence interval [CI], 1.1−6.4; p = 0.04) and less likely to consume iodine-containing supplements (OR = 0.3, 95% CI, 0.1−0.8; p = 0.01). It is possible that thyroid function may be affected by iodine insufficiency during pregnancy in regions with mild-to-moderate iodine deficiency. The relatively small sample size of the studied population warrants further investigation.

Results of the national biomonitoring program show persistent iodine deficiency in Israel.

BACKGROUND: Adequate iodine intake is essential for human health, for normal thyroid function, and for attainment of full intellectual potential in children. In light of Israel's lack of a mandatory salt fortification policy, heavy reliance on desalination and low iodine intake from dairy products and seafood, there is concern in Israel that the population is iodine deficient. Indeed, the first Israeli National Iodine Survey in 2016 found a median urinary iodine concentration (UIC) of 83 µg/L among school age children, falling below the WHO's adequacy range of 100-299 µg/L for children. METHODS: In the framework of the National Human Biomonitoring Program in Israel, spot urine samples and questionnaire data were collected from 166 healthy children aged 4-12 years in 2020-2021. Urinary iodine concentrations were measured at the Ministry of Health National Biomonitoring Laboratory, using mass spectrometry. An international comparison of median urinary iodine concentrations (UIC) was performed taking into consideration the levels of desalinated water per capita, and fortification policies. RESULTS: The overall median (interquartile range [IQR]) UIC was 80.1 µg/L (44.7-130.8 µg/L) indicating that the population's iodine status has not improved in the five years that have passed since inadequacy was first identified. When comparing 13 countries with population size above 150,000, whose desalinated water per capita was at least 1 m3, Israel and Lebanon were the only countries with median UIC below the WHO adequacy range. CONCLUSIONS: There is an urgent need for mandatory salt fortification in Israel. Based on our international comparison, we conclude that the potential impact of desalination on iodine intake can be compensated for using the implementation of salt fortification policy. This study highlights the critical need for public health surveillance of nutritional and environmental exposures using human biomonitoring, with emphasis on vulnerable populations such as pregnant women and children.