Iodine and Thyroid Maternal and Fetal Metabolism during Pregnancy

Overt hypothyroidism in pregnancy and language development in offspring: is there an association?

PURPOSE

Overt hypothyroidism during pregnancy is linked to various obstetric complications, such as premature birth and fetal death. While some studies have shown that maternal hypothyroidism can impact a child's Intelligence Quotient (IQ) and language development, findings are controversial. The aim of this study was to explore the connection between treated maternal hypothyroidism during pregnancy and offspring neurodevelopment, focusing on learning and language and examining related maternal obstetric complications.

METHODS

Group 1 included 31 hypothyroid women with elevated thyroid stimulating hormone (TSH) (> 10 mU/L, > 10 µIU/mL) during pregnancy, and Group 2 had 21 euthyroid women with normal TSH levels (0.5-2.5 mU/L, 0.5-2.5 µIU/mL). Children underwent neuropsycological assessments using the Griffiths-II scale.

RESULTS

Pregnancy outcome showed an average gestational age at delivery of 38.2 weeks for hypothyroid women, compared to 40 weeks for controls, and average birth weight of 2855.6 g versus 3285 g for controls, with hypothyroid women having children with higher intrauterine growth restriction (IUGR) prevalence and more caesarean sections. The 1-min APGAR score was lower for the hypothyroid group's children, at 8.85 versus 9.52. Neuropsychological outcomes showed children of hypothyroid mothers scored lower in neurocognitive development, particularly in the learning and language subscale (subscale C), with a notable correlation between higher maternal TSH levels and lower subscale scores.

CONCLUSION

Fetuses born to hypothyroid mothers appeared to be at higher risk of IUGR and reduced APGAR score at birth. Neurocognitive development seemed to affect language performance more than the developmental quotient. This alteration appeared to correlate with the severity of hypothyroidism and its duration.

Reference intervals for thyroid function from the fifth to seventh day of life in twin-pregnancy preterm neonates: an 8-year retrospective study

PURPOSE

The immature and developing hypothalamic-pituitary-thyroid axis leads to different levels of thyroid function in twin neonates, including free thyroxine (FT4), free triiodothyronine (FT3), and thyroid stimulating hormone (TSH) levels. No reference intervals for twins have been established until now. To compensate for this lack, we collected data and established this standard across different gestational ages (GAs) and sexes.

METHODS

A total of 273 pairs of neonates admitted to the NICU in Southeast China from 2015 to 2022 were included. Each pair was divided into Neonate A (relatively heavy birth weight (BW)) and Neonate B (relatively light BW). Their thyroid functions were analyzed to establish reference intervals and comparisons were made stratified by GA and sex.

RESULTS

The FT3, FT4, and TSH reference intervals in twin neonates with a GA of 26-36 weeks were as follows: Neonate A and B: 3.59 ± 0.99 and 3.57 ± 1.00 pmol/L; Neonate A and B: 17.03 ± 5.16 and 16.77 ± 5.29 pmol/L; and Neonate A and B: 4.097 ± 3.688 and 4.674 ± 4.850 mlU/L, respectively. There were significant differences between serum FT3 and FT4 reference intervals and GA (p < 0.05). The serum FT3 and FT4 reference intervals for male neonates were lower than those for female neonates in the 29-32-week group (p < 0.05).

CONCLUSION

This was the first study, to our knowledge, to establish reference intervals for thyroid function in twin neonates from the fifth to seventh day of life, which will be beneficial for the diagnosis and management of congenital hypothyroidism.

Iodine nutritional status and its associations with thyroid function of pregnant women and neonatal TSH

Introduction

Iodine serves as a crucial precursor for the synthesis of thyroid hormones and plays an import role in both pregnant women and their offspring. The relationships between iodine nutritional status and maternal thyroid function and neonatal outcomes remain inconclusive in areas with adequate iodine nutrition. This study aims to investigate their correlations.

Methods

Blood, morning urine and 24-hour urine were collected from the pregnant women to measure thyroid functions, serum iodine concentration (SIC), morning urine iodine concentration (UIC) and 24-hour urine iodine excretion (24-hour UIE). Indicators of their offspring's neonatal indexes were recorded.

Results

A total of 559 pregnant women were enrolled in this study. The iodine indicators including Tg, 24-hour UIE and morning UIC were significantly different among the euthyroid pregnant women and those with different thyroid disorders. The levels of FT3, FT4, and SIC exhibited a gradual decline and the concentration of TSH exhibited a gradual increase trend throughout the progression of pregnancy in euthyroid pregnant women. There were no significant differences in neonatal outcomes and neonatal TSH values among euthyroid pregnant women and thyroid disorders pregnant women. SIC had a significant impact on maternal FT4 levels throughout all three trimesters, with varying degrees of importance observed in each trimester. TSH level emerged as the primary determinant of FT4 during the first trimester, while SIC exerted a predominant influence on FT4 levels in the second and third trimesters. The prevalence of thyroid disorders in pregnant women was the lowest when the SIC of pregnant women was probable in the range of 60~70 μg/L, 24-hours UIE was in the range of 250~450 μg, and Tg was in the range of 9~21 μg/L. Maternal TSH exhibited a notable influence on neonatal TSH levels, particularly at the 50th and 75th quantiles. Among the iodine nutritional indicators, SIC and morning UIC demonstrated higher AUC values for abnormal FT4 and TSH, respectively.

Discussion

The iodine nutrition status of pregnant women exerts an impact on their thyroid function and prevalence of thyroid disorders, and neonatal TSH was affected by maternal TSH. SIC may be a better indicator for iodine nutritional assessment than other indexes.

Maternal plasma phospholipid polyunsaturated fatty acids in early pregnancy and thyroid function throughout pregnancy: a longitudinal study

BACKGROUND

Evidence has indicated that polyunsaturated fatty acids (PUFAs)-enriched diet could reduce inflammation because of thyroid autoimmunity in vivo, and therefore, enhance thyroid function.

OBJECTIVES

We investigated whether early pregnancy plasma phospholipid PUFAs could benefit maternal thyroid function across pregnancy, which is critical to fetal brain development and growth in pregnancy.

METHODS

Within the National Institute of Child Health and Human Development Fetal Growth Studies-Singleton Cohort, we collected plasma samples longitudinally from 214 subjects [107 with gestational diabetes mellitus (GDM) matched with 107 controls] with a singleton pregnancy. We measured 11 PUFAs at early pregnancy (10-14 wk) and 5 thyroid biomarkers at 10-14, 15-26, 23-31, and 33-39 wk, including free thyroxine (fT4), free triiodothyronine (fT3), thyroid-stimulating hormone, antithyroid peroxidase, and antithyroglobulin. Associations of PUFAs with thyroid function biomarkers and relative risk (RR) of gestational hypothyroidism (GHT) during pregnancy were assessed using generalized linear mixed models and modified Poisson regression, respectively.

RESULTS

After sample weighting because of subjects with GDM over-representing in the analytic sample with biomarkers, eicosapentaenoic acid (EPA) at early pregnancy was associated with a reduction of 0.24 pmol/L (95% confidence intervals: -0.31, -0.16) in fT3 across gestation per standard deviation (SD) increment, whereas docosahexaenoic acid (DHA) at early pregnancy was associated with an increment of 0.04 ng/dL (0.02, 0.05) in fT4 across gestation per SD increment. Furthermore, EPA and docosatetraenoic acid (DTA) were associated with lower risks of persistent GHT (EPA-RR: 0.13; 0.06, 0.28; DTA-RR: 0.24; 0.13, 0.44) per SD increment. All significant associations remained robust in sensitivity analysis and multiple testing.

CONCLUSIONS

Certain plasma phospholipid PUFAs were associated with optimal levels of thyroid biomarkers and even lower risk of GHT throughout pregnancy, which might be potentially targeted for maternal thyroid regulation in early pregnancy.

CLINICAL TRIAL REGISTRY

This trial was registered at https://beta.

CLINICALTRIALS

gov/study/NCT00912132?distance=50&term=NCT00912132&rank=1 as NCT00912132.

Assessment of Individual and Mixed Effects of Six Minerals on Thyroid Hormones in Chinese Pregnant Women

The biosynthesis of thyroid hormones is essential for brain and neurological development. It requires iodine as a key component but is also influenced by other nutrients. Evidence for the combined nutrient status in relation to thyroid hormones during pregnancy is limited. We aimed to investigate the joint associations of iodine, selenium, zinc, calcium, magnesium and iron with maternal thyroid functions in 489 pregnant women from Hangzhou, China. Serum levels of six essential minerals and thyroid function parameters were measured during the first antenatal visit. Linear regression, quantile g-computation and Bayesian kernel machine regression were used to explore the individual and joint relationships between the six minerals and thyroid hormones. Linear regression analyses revealed that calcium was positively associated with free triiodothyronine (FT3). Zinc was positively associated with free thyroxine (FT4). Iodine was negatively associated with thyroid-stimulating hormone (TSH) and positively associated with FT3 and FT4. The quantile g-computation and BKMR models indicated that the joint nutrient concentration was negatively associated with TSH and positively associated with FT3 and FT4. Among the six minerals, iodine contributed most to thyroid function. The findings suggested that maintaining the appropriate concentration of minerals, either as individuals or a mixture, is important for thyroid health during pregnancy.

Evaluation of Salvia hispanica as a Therapeutic Agent against Sodium Arsenic-Induced Testicular Toxicity in a Male Rats Model

Chia seeds offer therapeutic properties that aid in the prevention of a variety of ailments, including cardiovascular disease, diabetes, obesity, and other risk factors. Arsenite, a common environmental chemical, has been identified as a reproductive toxin owing to its negative effects on male reproductive health. It has been shown to inhibit spermatogenesis and generate androgenic effects in men. The primary goal of this research was to look into the effect of Salvia hispanica on testicular toxicity caused by sodium arsenite in male rats. A set of 36 male albino rats was allocated to a negative control cohort. The individuals in this group were given a basic meal and orally given distilled water for a duration of 28 days. The other five groups were given a regular meal and received intra-peritoneal injections of sodium arsenite (NaAsO2) at a concentration of 4 mg/kg body weight that was diluted in a 0.9% NaCl solution. The injections were administered consecutively, with two doses given within a two-day period. Subsequently, the rats were categorized into several groups using the following classification: Group 2 consisted of a positive control cohort, in which the rats were given a typical baseline diet. Groups 3, 4, 5, and 6 were given a basic diet that included varying proportions of ground chia seeds, namely 5%, 10%, 15%, and 20% per 100 g of the diet. After the trial was completed, the rats were euthanized, and further biological examination was conducted. The measurements of the reproductive organs were documented and reported. The research assessed the following characteristics: sperm count, motility, progressive motility, and normal morphology. The research included examining serum sex hormones, namely luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone. An evaluation of the activity of antioxidant enzymes was performed in the tissue of the testicles. There were statistically significant improvements in the sperm parameters, serum sex hormone levels, and the activity of antioxidant enzymes, such as GPX, SOD, and CAT, in the therapy groups. The levels of malondialdehyde (MDA) exhibited a noteworthy decrease (p ≤ 0.05) when compared to the positive control group. Salvia hispanica seeds have demonstrated a significant level of effectiveness in reducing sodium arsenite-induced testicular toxicity, which leads to the conclusion. The flavonoid content and antioxidant properties of Salvia hispanica seeds may be to blame for the observed behavior. These indicated characteristics may have therapeutic significance in treating testicular harm induced by arsenite exposure.

Evaluation of the reliability and readability of ChatGPT-4 responses regarding hypothyroidism during pregnancy

Hypothyroidism is characterized by thyroid hormone deficiency and has adverse effects on both pregnancy and fetal health. Chat Generative Pre-trained Transformer (ChatGPT) is a large language model trained with a very large database from many sources. Our study was aimed to evaluate the reliability and readability of ChatGPT-4 answers about hypothyroidism in pregnancy. A total of 19 questions were created in line with the recommendations in the latest guideline of the American Thyroid Association (ATA) on hypothyroidism in pregnancy and were asked to ChatGPT-4. The reliability and quality of the responses were scored by two independent researchers using the global quality scale (GQS) and modified DISCERN tools. The readability of ChatGPT was assessed used Flesch Reading Ease (FRE) Score, Flesch-Kincaid grade level (FKGL), Gunning Fog Index (GFI), Coleman-Liau Index (CLI), and Simple Measure of Gobbledygook (SMOG) tools. No misleading information was found in any of the answers. The mean mDISCERN score of the responses was 30.26 ± 3.14; the median GQS score was 4 (2-4). In terms of reliability, most of the answers showed moderate (78.9%) followed by good (21.1%) reliability. In the readability analysis, the median FRE was 32.20 (13.00-37.10). The years of education required to read the answers were mostly found at the university level [9 (47.3%)]. Although ChatGPT-4 has significant potential, it can be used as an auxiliary information source for counseling by creating a bridge between patients and clinicians about hypothyroidism in pregnancy. Efforts should be made to improve the reliability and readability of ChatGPT.

Microbial involvement in iodine cycle: mechanisms and potential applications

Stable iodine isotopes are essential for humans as they are necessary for producing thyroid gland hormones. However, there are hazardous radioactive iodine isotopes that are emitted into the environment through radioactive waste generated by nuclear power plants, nuclear weapon tests, and medical practice. Due to the biophilic character of iodine radionuclides and their enormous biomagnification potential, their elimination from contaminated environments is essential to prevent the spread of radioactive pollution in ecosystems. Since microorganisms play a vital role in controlling iodine cycling and fate in the environment, they also can be efficiently utilized in solving the issue of contamination spread. Thus, this paper summarizes all known on microbial processes that are involved in iodine transformation to highlight their prospects in remediation of the sites contaminated with radioactive iodine isotopes.

Maternal Urinary Iodine Concentration during Pregnancy and Its Impact on Child Growth and Neurodevelopment: An 11-Year Follow-Up Study

Mild-to-moderate iodine deficiency during pregnancy is prevalent worldwide, but its consequences for maternal and child health are not clear. We aimed to investigate the impact of maternal iodine intake during pregnancy on the child's growth and neurodevelopment. This study involved a cohort of 11-year-old children (n = 70) whose mothers had participated in an iodine intake survey during pregnancy. Gestational, neonatal, anthropometric, intelligence quotient (IQ), and socioeconomic parameters were analyzed according to maternal urinary iodine concentration (UIC). There was a positive linear trend of current height Z-score, full-scale IQ, verbal IQ, family income, maternal education, and a negative trend of neonatal TSH levels with increasing maternal UIC levels. However, regression analysis indicated that maternal UIC was not an independent predictor of any gestational, neonatal, or childhood development parameter. Only maternal school education was positively associated with child height and IQ. In conclusion, we did not find any evidence of a direct effect of maternal iodine intake during pregnancy on the long-term growth and neurodevelopment of children. The results suggest that socioeconomic factors are important confounding factors that affect both maternal iodine intake and child development and must be considered when investigating the association between maternal iodine intake and child outcomes.

Associations of Maternal Serum Iodine Concentration with Obstetric Complications and Birth Outcomes-Longitudinal Analysis Based on the Huizhou Mother-Infant Cohort, South China

This study aimed to explore the temporal associations between maternal serum iodine concentration (SIC) and common pregnancy outcomes in Chinese women. Eligible singleton pregnant women aged 20-34 years were selected, and their fasting blood samples were collected during early (T1, n = 1101) and mid-pregnancy (T2, n = 403) for SIC testing by inductively coupled plasma mass spectrometry. Multivariable linear regression indicated that log₁₀SIC at T1 (β = -0.082), T2 (β = -0.198), and their % change (β = -0.131) were inversely associated with gestational weight gain (GWG, all p < 0.05). Maternal log₁₀SIC at both T1 (β = 0.077) and T2 (β = 0.105) were positively associated with the Apgar score at 1 min (both p < 0.05). Women in the third quartile (Q3) of SIC at T1 had a lower risk of small for gestational age (SGA, OR = 0.405, 95% CI: 0.198-0.829) compared with those in Q4. Restricted cubic spline regression suggested a U-shaped association between SIC and SGA risk, and SIC above 94 μg/L at T1 was the starting point for an increased risk of SGA. The risk of premature rupture of membrane (PROM) increased by 96% (OR = 1.960, 95% CI: 1.010-3.804) in Q4 compared to that in Q1. Our longitudinal data from an iodine-replete region of China indicated that high maternal SIC could restrict GWG and improve Apgar scores at delivery, but might increase the risk of SGA and PROM.