Maternal thyroid hormone insufficiency during pregnancy and risk of neurodevelopmental disorders in offspring: A systematic review and meta-analysis

Risk Factors for Thyroid Function Test Abnormalities During Pregnancy: A Systematic Review of the Literature to Validate Current Risk Factors and Identify Novel Ones

Background: International guidelines recommend that the indication to perform thyroid function testing during pregnancy is based on the presence of risk factors for thyroid function test abnormalities. However, the discriminative ability of currently recommended risk factors is questionable. To inform on an update of the American Thyroid Association Guidelines for the Diagnosis and Management of Thyroid Disease in Preconception, Pregnancy, and the Postpartum, we aimed to systematically review the literature to evaluate evidence for current risk factors and potential novel ones for thyroid function test abnormalities in pregnancy. Methods: A systematic literature search was performed on Embase, Medline Ovid, and the Cochrane Library from inception to October 17, 2024, to identify articles on the associations of any candidate variables with thyroid function test abnormalities, thyroid antibody positivity, or results of continuous thyroid function tests in pregnancy. Additional records were identified through citation searching. Study quality was assessed using the Newcastle-Ottawa Scale. We summarized the results using a narrative synthesis. Results: A total of 81 articles were included, describing 36 candidate variables. Thyroid antibody positivity was associated with a higher risk of overt or subclinical hypothyroidism compared with antibody negativity (absolute risks: 2.4-7.0% vs. 0.1-0.2% for overt hypothyroidism and 1.9-29.0% vs. 2.0-5.7% for subclinical hypothyroidism). In cases of iodine deficiency, sufficiency, and intake above pregnancy requirements or excess, the absolute risks for subclinical hypothyroidism were 2.2-42.6%, 1.42-16.0%, and 3.8-24.3%, respectively. A limited number of studies were available for history of autoimmune diseases, family history of thyroid disease, symptoms of hypothyroidism, and history of pregnancy loss, preterm delivery, or infertility. There was little or no association of current risk factors with isolated hypothyroxinemia or (subclinical) hyperthyroidism. We did not identify novel risk factors for thyroid function test abnormalities. Conclusions: Evidence for most currently recommended risk factors remains limited and heterogeneous, and no novel risk factor was identified. While risk factors can help guide thyroid function testing in pregnancy, a clinical risk assessment cannot be replaced. Future studies are needed to detect novel risk factors that can improve the accuracy and efficiency of identifying pregnant women at high risk of thyroid function test abnormalities, in particular, overt hypothyroidism.

Overview of thyroid disorders in pregnancy

Thyroid disorders rank as the second most common endocrine abnormalities during pregnancy, posing significant challenges for clinical diagnosis due to overlapping symptoms with normal pregnancy. Thyroid hormones play a critical role in fetal growth and neurocognitive development, necessitating precise interpretation of maternal thyroid function tests, which differ from non-pregnant states. Proper management of thyroid dysfunction can significantly reduce morbidity in both mothers and their fetuses.This review explores the physiological changes in thyroid function during pregnancy, the epidemiology of thyroid disorders, and current guidelines for diagnosis and management. Pregnancy induces anatomical and physiological changes in the thyroid gland, including an increase in gland size and alterations in hormone levels influenced by factors such as hCG and estrogen. These changes necessitate trimester-specific reference ranges for thyroid function tests, as the American Thyroid Association and the American College of Obstetricians and Gynecologists recommended. Hyperthyroidism, primarily caused by Graves' disease and gestational transient thyrotoxicosis, can lead to complications like preeclampsia, preterm birth, and fetal hyperthyroidism. Management includes antithyroid drugs, with careful monitoring to balance maternal and fetal risks. Hypothyroidism, including subclinical and overt forms, is predominantly due to autoimmune thyroiditis and poses risks such as spontaneous abortion, preterm delivery, and impaired neurodevelopment in offspring. The review discusses the debated benefits of levothyroxine treatment for subclinical hypothyroidism, highlighting the need for further research to establish clear guidelines.Given the complex interplay between thyroid function and pregnancy outcomes, this comprehensive review underscores the importance of tailored, evidence-based approaches to managing thyroid disorders in pregnant women.

Subclinical hypothyroidism in pregnancy: an evolving and controversial landscape

PURPOSE OF REVIEW

This review aims to elucidate the developments in subclinical hypothyroidism (SCH) in pregnancy effects, management, and treatment. While mostly focusing on recent research, landmark studies are briefly reviewed to highlight major developments since their publication.

RECENT FINDINGS

Research has continued to show an increased risk of adverse outcomes in pregnant women with SCH, with recent research showing an increased risk of both impaired glucose tolerance and hypertensive disorders of pregnancy. Research has continued to show unclear effects of SCH on neonatal outcomes, specifically in offsprings' intellectual development and ability. The benefit of treatment of SCH continues to be unclear; however, data suggest that treatment for thyroid stimulating hormone (TSH) 2.5-4 mU/l regardless of thyroid peroxidase antibodies status and TSH 4-10 mU/l in later pregnancy has not shown maternal or neonatal benefit.

SUMMARY

With varying guidelines and inconsistent research outcomes, it is not surprising that SCH practices differ widely. Further research, with uniform definitions and criteria of SCH, is needed to elucidate the optimal management and treatment of this common pregnancy condition. Additionally, further research specifically aimed at optimizing TSH in preconception and early pregnancy is needed.

Impacts of Gestational F-53B Exposure on Fetal Neurodevelopment: Insights from Placental and Thyroid Hormone Disruption

It has been evidenced that chlorinated polyfluoroalkyl ether sulfonic acids (Cl-PFESAs) have strong potential cross the placental barrier, but their adverse effects on offspring remain unclear. In this study, pregnant mice received daily intraperitoneal injections of chlorinated polyfluorinated ether sulfonate (Cl-PFESA; commercially known as F-53B, primarily comprising 6:2 Cl-PFESA and 8:2 Cl-PFESA) at dosages of 40 and 200 μg/kg from gestational days 6 to 17. Following gestational exposure, distinct accumulation of 6:2 and 8:2 Cl-PFESAs was observed in both the placenta and fetal brain, confirming their penetration across the placental and fetal blood-brain barriers. Maternal exposure to F-53B disrupted the placental 11β-hydroxysteroid dehydrogenase type 2 (hsd11b2) barrier, characterized by hypermethylation of its promoter, decreased blood sinusoids in labyrinth layer, and downregulation of the nutrient transport genes, thereby severely impairing the placenta's protective and nutrient transfer functions. Concomitantly, significant fetal intrauterine growth restriction indicated by decreased fetal weight and crown-rump length was observed. Additionally, changes in thyroid hormones, along with transcriptional and DNA methylation alterations in the promoter regions of transthyretin (ttr) and deiodinase 3 (dio3) genes, were noted in the placenta. These epigenetic changes might affect the maternal-fetal transport of thyroid hormones, possibly leading to disrupted thyroid function in the F1 generation. With the decreased nutrient transport capacity of the placenta, T4 levels in the fetus are significantly reduced, resulting in significant fetal neurodevelopmental abnormalities, reduced nerve cell proliferation (Ki67), and damage to synaptic plasticity. This study reveals unveil the hidden dangers of F-53B, highlighting its neurotoxic effects on fetal development through the disruption of thyroid hormone transport across the placenta.

Controlled Antenatal Thyroid Screening Study III: Effects of Gestational Thyroid Status on Adolescent Brain Morphology

CONTEXT

Children born to mothers with gestational hypothyroidism or hyperthyroidism may have increased risk of adverse neurodevelopmental outcomes. However, the effects of maternal thyroid status on offspring brain development are unclear.

OBJECTIVE

This work aimed to establish whether adolescent brain morphology is affected by suboptimal gestational thyroid function (SGTF).

METHODS

The Controlled Antenatal Thyroid Screening (CATS) study randomly assigned mothers with SGTF to levothyroxine or no supplementation from approximately 12 weeks' gestation. At age 9, children born to mothers who were overtreated with levothyroxine had a higher risk of conduct and hyperactivity traits. For the current CATS III study, children underwent neuroimaging studies, including T1-weighted structural magnetic resonance imaging (MRI). A total of 85 children aged 11 to 16 years had usable T1-weighted MRI data (exposed to untreated SGTF [n = 21], normal GTF [n = 24], or treated SGTF [optimally treated (n = 21), overtreated (n = 20)]). The primary outcome was to examine the association of SGTF and its treatment with global brain volumes. Secondary and exploratory outcomes were to investigate the association of maternal thyrotropin (TSH) and free thyroxine (FT4) levels with global and subregional brain volumes. Results were adjusted for age, sex, and pubertal scores.

RESULTS

There were no significant differences in global brain volumetric measures between groups, including total gray matter volume (P = .373). Weak positive correlations were found between maternal TSH, but not FT4, levels and several brain volumes, but these did not survive testing for multiple comparisons.

CONCLUSION

We found no evidence that SGTF was associated with differences in adolescent brain morphology, and no effect of levothyroxine supplementation.

Maternal Thyroid Function in Early Pregnancy and Offspring School Performance and Neurodevelopmental Disorders

CONTEXT

Thyroid hormones are critical for neural development, and during the first trimester of pregnancy, the fetus relies fully on maternal thyroid hormone production.

OBJECTIVE

To investigate the associations between maternal thyroid hormone levels in the first trimester with the child's school performance, risk of attention deficit hyperactivity disorder (ADHD), and autism spectrum disorder (ASD).

METHODS

Information from the Copenhagen Primary Care Laboratory Pregnancy Database on first trimester TSH and free thyroxine measurements in mothers of children born in 2000 through 2014 were linked with information on the child's standardized test scores in school, ADHD (patient record diagnoses and medication), and ASD (patient record diagnoses) until the end of 2018. Associations of TSH and free thyroxine with the outcomes were individually assessed by linear mixed models and Cox regression models. The analyses were stratified by preexisting maternal thyroid disorders.

RESULTS

TSH measurements were available for 17 909 mother-child dyads. Among those with children born in 2000 through 2009, 6126 had a standardized school test score and were analyzed for the association between maternal thyroid hormone levels and child's school performance, and no support for an association was found. The association between thyroid hormone levels and child's risk of ADHD and ASD were analyzed for the 17 909 dyads and with no support for an association between thyroid hormone levels and these neurodevelopmental disorders. Stratification by preexisting maternal thyroid disorders did not affect the results.

CONCLUSION

We found no evidence for associations between first trimester maternal thyroid hormone levels and child's school performance, or risk of ADHD or ASD.

Early-life exposure to PCBs and PFAS exerts negative effects on the developing central nervous system

Persistent organic pollutants (POPs) are ubiquitous in the environment and display the capacity to bioaccumulate in living organisms, constituting a hazard to both wildlife and humans. Although restrictions have been applied to prohibit the production of several POPs since the 1960s, high levels of these compounds can still be detected in many environmental and biological matrices, due to their chemical properties and significantly long half-lives. Some POPs can be passed from mother to the fetus and can gain entry to the central nervous system (CNS), by crossing the blood-brain barrier (BBB), resulting in significant deleterious effects, including neurocognitive and psychiatric abnormalities, which may lead to long-term socio-economic burdens. A growing body of evidence obtained from clinical and experimental studies has increasingly indicated that these POPs may influence neurodevelopment through several cellular and molecular mechanisms. However, studies assessing their mechanisms of action are still incipient, requiring further research. Polychlorinated biphenyls (PCBs) and per- and polyfluoroalkyl substances (PFAS) are two of the main classes of POPs associated with disturbances in different human systems, mainly the nervous and endocrine systems. This narrative review discusses the main PCB and PFAS effects on the CNS, focusing on neuroinflammation and oxidative stress and their consequences for neural development and BBB integrity. Moreover, we propose which mechanisms could be involved in POP-induced neurodevelopmental defects. In this sense, we highlight potential cellular and molecular pathways by which these POPs can affect neurodevelopment and could be further explored to propose preventive therapies and formulate public health policies.

Effects of organophosphate esters on thyroid function during pregnancy: Risk of endocrine disruptors during early- and mid-pregnancy

Organophosphate esters (OPEs) can disrupt thyroid function, but the association between OPEs and thyroid function is limited. In this study, the association between OPEs and thyroid hormones (THs) was studied. The study population was comprised of two groups: early-pregnancy and mid-pregnancy. The results showed that in all-pregnancies group, tri-n-butyl-phosphate (TNBP) and tris(2-chloroisopropyl) phosphate (TCIPP) were positively correlated with thyroid-stimulating hormone (TSH) levels, whereas tris(2-chloroethyl) phosphate (TCEP) was positively correlated with the free thyroxine (FT4)/free triiodothyronine (FT3) ratio. In early-pregnancy group, 2-ethylhexyl diphenyl phosphate (EHDPP) and tris(2-ethylhexyl) phosphate (TEHP) were correlated with FT3 and FT4 levels, respectively. TNBP was positively correlated with TSH levels, and TEHP was negatively correlated with FT4/FT3 ratio. In the mid-pregnancy group, no significant association was observed between OPEs and THs. Restricted cubic spline analysis revealed that, in all-pregnancies group, TNBP, tris (methylphenyl) phosphate (TMPP), and TCIPP were correlated with TSH/FT4 ratios, reflecting homeostasis of the hypothalamic-pituitary-thyroid (HPT) axis. In early-pregnancy group, TNBP was correlated with TSH/FT4 ratios and TCIPP was correlated with TSH levels. These associations exhibited L-shaped relationship. However, the overall effect of total OPEs on THs levels was not significant. In addition, TPOAb statue could alter the association between OPEs and THs. These findings indicated that OPEs could disrupt maternal THs homeostasis and interfere with the HPT axis, requiring additional human-supported experiments to explore OPE-induced thyroid disruption mechanisms.

Urinary Iodine Concentration and Thyroid Hormone Metabolism in Pregnant Women and Neurodevelopment in Their Children: A Longitudinal Canadian Birth Cohort

Background/Objectives: Iodine is essential for thyroid hormone (TH) synthesis, and THs in pregnant women are critical for fetal brain development. It is unclear whether urinary iodine concentrations (UICs) are associated with thyroid parameters in pregnant women and neurodevelopment in their 3-4-year-old children. Methods: In the Canadian Maternal-Infant Research on Environmental Chemicals (MIREC) cohort, we categorized UIC adjusted for urinary creatinine (UIC/Cr) in the first two trimesters as <150, 150-500, or ≥500 µg/g. We used multivariable regression to quantify associations between UIC/Cr and thyroid parameters in maternal plasma (n = 1501), including thyroid stimulating hormone (TSH), total T4 (tT4), free T4 (fT4), thyroglobulin (Tg) and Tg antibodies (TgAb), and thyroid peroxidase antibodies (TPOAb). We defined positive thyroid autoantibodies as TgAb ≥ 4.11 or TPOAb ≥ 5.61 IU/mL. We also examined the associations between UIC/Cr with the Wechsler Preschool and Primary Scale of Intelligence (n = 503), Behavior Assessment System for Children (n = 751), and the Social Responsiveness Scale (n = 498). Results: Twenty-two percent of women had UIC/Cr < 150 and 17% ≥ 500 µg/g. UIC/Cr was not associated with TSH, tT4, or fT4. After excluding women with positive thyroid autoantibodies, those with UIC/Cr < 150 µg/g had higher tT4 compared to those with 150-500 µg/g. Compared to women with UIC/Cr 150-500 µg/g, those with UIC/Cr < 150 had higher Tg and, those with UIC/Cr ≥ 500 had less frequent positive thyroid autoantibodies. Neurodevelopmental outcomes were not associated with maternal Tg, nor did they differ for maternal UIC/Cr < 150 and ≥500 compared to 150-500 µg/g. Conclusions: In this cohort, Tg and tT4 were higher in women with UIC/Cr < 150 µg/g compared to those with UIC/Cr 150-500 µg/g. Urinary iodine in pregnant women was not associated with neurodevelopment in their 3-4-year-old children.

Associations of gestational exposure to organophosphate esters with thyroid hormones in cord plasma and the safety threshold of exposure in pregnant women

BACKGROUND

As a class of synthetic chemicals, organophosphate esters (OPEs) were shown to have thyroid hormones (THs) disrupting potentials in animal studies, while epidemiological evidence on gestational exposure to OPEs and thyroid disruption is limited. Besides, assessment on the safety threshold of OPEs exposure during gestation is especially scarce.

METHODS

Based on the Shanghai Minhang Birth Cohort Study, we measured maternal urine concentration of 8 OPE metabolites and THs levels in cord plasma and examined their associations using multiple linear regression and quantile g-computation (QGC) models. The benchmark dose (BMD) and its lower limit (BMDL) of urine OPE metabolites concentrations were further estimated via the Bayesian Benchmark Dose Analysis System (BBMD) to reflect the safety threshold of exposure in pregnant women. The corresponding daily intake (DI) of BMDL was then calculated and compared with the current oral reference dose (RfD).

RESULTS

A total of 309 mother-newborn pairs were included in this study. Gestational bis (2-butoxyethyl) phosphate (BBOEP) exposure was associated with higher total triiodothyronine (TT3), free triiodothyronine (FT3), total thyroxine (TT4), and free thyroxine (FT4) in cord plasma, while bis(1,3-dichloro-2-propyl) phosphate (BDCPP) was observed to be associated with lower TT3 and FT3/FT4 but higher thyroid stimulating hormone (TSH). In addition, sex-specific effects were observed for bis (2-chloroethyl) phosphate (BCEP), which was associated with lower TT3 in cord plasma of female newborns, and lower TT4 and FT4 in male newborns. Similar results were obtained through QGC model and BBOEP was identified as the main contributor to the higher levels of TT3 and FT3. With benchmark response (BMR) of 10% and background response (P0) of 97.5% for both TT3 and FT3, the BMDL10 of urine BBOEP concentration was 0.50 μg/L. Further, the corresponding DI of tris (2-butoxyethyl) phosphate (TBOEP), which is the precursor of BBOEP, was 2.53 μg/kg BW/d.

CONCLUSIONS

Our findings suggest associations between gestational exposure to OPEs and altered THs biomarkers. According to the estimated BMD10 (BMDL10) of BBOEP and the corresponding DI, the current RfD of 15 μg/kg BW/d for TBOEP may not protect pregnant women and their newborns from thyroid disruption.

Characterization of thyroid hormone transport in a human choroid plexus papilloma cell line (HIBCPP) as an in vitro blood-cerebrospinal fluid barrier model

Adequate levels of thyroid hormones (THs) in the fetal brain are vital for early neurodevelopment. Most of the TH in fetal brain is derived from circulating thyroxine (T4), which gets locally converted into the biologically active triiodothyronine (T3) by deiodinase enzymes. One of the major routes of TH into the brain is through the blood-cerebrospinal fluid barrier (BCSFB). The BCSFB is maintained by the choroid plexus (CP), which separates the blood from the cerebrospinal fluid (CSF). TH transport across the BCSFB is facilitated by TH transmembrane transporters (THTMTs) present in the CP. However, TH transport across the BCSFB is still poorly understood as there is a lack of human representative BCSFB models. Previously, a human choroid plexus papilloma cell line (HIBCPP) has been established, which exhibits certain key characteristics of the human CP. In this study, the suitability of the HIBCPP cell line as a human in vitro BCSFB model for TH transport was evaluated. For this, HIBCPP cells were grown on transwell inserts and the gene and protein expression of several THTMTs was assessed using qPCR and immunohistochemistry. Additionally, the transport of T4 across a HIBCPP monolayer was assessed using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), with a special focus on the role of transthyretin (TTR), a TH binding protein produced by the CP involved in TH transport across the BCSFB. Finally, inhibition studies were performed with various THTMT inhibitors, to conclude which THTMT drive TH transport across the BCSFB. Gene and protein expression data showed that several THTMTs were expressed in the HIBCPP model, however HIBCPP cells lacked key THTMTs, notably monocarboxylate transporter 8 (MCT8) and organic anion transporter polypeptide 1C1 (OATP1C1), known to be highly expressed in the human BCSFB. Moreover, TH transport across the HIBCPP model was low and addition of TTR did not increase this transport. Two TTR-binding chemicals, TBBPA and F21388, significantly decreased the transport of T4 across the HIBCPPs cells, suggesting a possible role of intracellular TTR in the transport of T4 across the BCSFB. The transport of TTR-T4 complex might be mediated through SR-B1, indicated by the decreased T4 transport after BLT-1 exposure. However, the poor expression of several important THTMTs, together with the low amount of TH transport, indicate that the HIBCPP cells lack key features that drive TH transport in the BCSFB. The HIBCPP cells could serve as a model to further study the mechanisms of TTR driven TH transport, but for the identification of THTMTs more in vivo accurate BCSFB models are necessary.

Effects of subclinical hypothyroidism during pregnancy on mtDNA methylation in the brain of rat offspring

OBJECTIVE

This study aims to investigate the impact of subclinical hypothyroidism (SCH) during pregnancy on mitochondrial DNA (mtDNA) methylation in the brain tissues of rat offspring.

MATERIALS AND METHODS

Sixteen SD rats were randomly divided into two groups: control group (CON) and SCH group. BS-seq sequencing was used to analyze mtDNA methylation levels in the offspring's brain tissues; the 2,7-dichlorofluorescin diacetate (DCFH-DA) probe method was employed to detect reactive oxygen species (ROS) levels in brain tissues; electron microscopy was utilized to observe the mitochondrial structure in the hippocampal tissues of the offspring.

RESULTS

In the analysis of differentially methylated regions (DMRs), the mitochondrial chromosome in the SCH group exhibited 23 DMRs compared to the control group. ROS levels in the brain tissues of the SCH group were significantly higher than those in the control group (P < 0.05). The mitochondrial structure in the hippocampus of the SCH group was less intact compared to the CON group.

CONCLUSION

Subclinical hypothyroidism in pregnant rats may alter the mtDNA methylation pattern in the brains of their offspring, potentially affecting mitochondrial function and structure.

Thyroid Function and Brain Structure: Insight from a Mendelian Randomization Study

INTRODUCTION

Thyroid hormones play a critical role in brain development. However, the precise causal associations between thyroid function and structural changes in specific brain regions remain uncertain.

METHODS

We applied the univariate Mendelian randomization (UVMR) method to assess the causal effects of thyroid function on brain structure. Genome-wide association study (GWAS) data on thyroid-related traits from the ThyroidOmics Consortium including free thyroxine (FT4), free tri-iodothyronine (FT3), thyroid-stimulating hormone (TSH), FT3/FT4 ratio, as well as dichotomized high and low TSH levels were used as exposures. GWAS data on cortical thickness, surface area, and volume of subcortical structures served as outcomes. Inverse variance weighted was the main estimate method. Subsequently, multivariable MR (MVMR) was conducted to validate significant causal associations identified in UVMR.

RESULTS

UVMR analysis demonstrated a statistically significant inverse association between genetically predicted FT4 and putamen volume (β = -71.91 mm3, 95% confidence interval: -112.11 mm3 to -31.71 mm3, p = 4.54 × 10-4). The findings were robust in sensitivity analysis. MVMR analysis further confirmed a persistent causal relationship between FT4 and putamen volume after adjusting for FT3, TSH, and neuropsychiatric disorders. Functional enrichment analyses indicated the pathways by which FT4 influences putamen volume may be related to the thyroid hormone signaling pathway, sodium-independent organic anion transport, and Rap1 signaling pathway.

CONCLUSION

MR analysis provides evidence for causal relationships between thyroid function and brain structural alterations, particularly highlighting the impact of FT4 on putamen volume. Further research is warranted to elucidate the underlying mechanisms by which thyroid hormones modulate brain structure.

Defining Gestational Thyroid Dysfunction Through Modified Nonpregnancy Reference Intervals: An Individual Participant Meta-analysis

BACKGROUND

Establishing local trimester-specific reference intervals for gestational TSH and free T4 (FT4) is often not feasible, necessitating alternative strategies. We aimed to systematically quantify the diagnostic performance of standardized modifications of center-specific nonpregnancy reference intervals as compared to trimester-specific reference intervals.

METHODS

We included prospective cohorts participating in the Consortium on Thyroid and Pregnancy. After relevant exclusions, reference intervals were calculated per cohort in thyroperoxidase antibody-negative women. Modifications to the nonpregnancy reference intervals included an absolute modification (per .1 mU/L TSH or 1 pmol/L free T4), relative modification (in steps of 5%) and fixed limits (upper TSH limit between 3.0 and 4.5 mU/L and lower FT4 limit 5-15 pmol/L). We compared (sub)clinical hypothyroidism prevalence, sensitivity, and positive predictive value (PPV) of these methodologies with population-based trimester-specific reference intervals.

RESULTS

The final study population comprised 52 496 participants in 18 cohorts. Optimal modifications of standard reference intervals to diagnose gestational overt hypothyroidism were -5% for the upper limit of TSH and +5% for the lower limit of FT4 (sensitivity, .70, CI, 0.47-0.86; PPV, 0.64, CI, 0.54-0.74). For subclinical hypothyroidism, these were -20% for the upper limit of TSH and -15% for the lower limit of FT4 (sensitivity, 0.91; CI, 0.67-0.98; PPV, 0.71, CI, 0.58-0.80). Absolute and fixed modifications yielded similar results. CIs were wide, limiting generalizability.

CONCLUSION

We could not identify modifications of nonpregnancy TSH and FT4 reference intervals that would enable centers to adequately approximate trimester-specific reference intervals. Future efforts should be turned toward studying the meaningfulness of trimester-specific reference intervals and risk-based decision limits.

Association of hepatitis B virus and thyroid hormones during pregnancy

This study aims to evaluate the correlation between serum thyroid hormone levels and hepatitis B virus (HBV) DNA and HBV genotypes in pregnant women with chronic hepatitis B. A total of 96 pregnant women with chronic HBV-infected pregnant women between January 2020 and December 2022 were selected as the observational study subjects. About 50 HBV-uninfected pregnant women during the same period were selected as the control group. Serum thyroid hormone levels at different stages of pregnancy, including free triiodothyronine (FT3), free thyroxine (FT4), thyroid stimulating hormone (TSH), thyroperoxidase antibody (TPOAb), and thyroglobulin antibody (TGAb), were compared between the 2 groups. Thyroid hormones levels were also compared between HBV-DNA-positive and HBV-DNA-negative women in the HBV-infected pregnancy group, and to determine the correlation between thyroid hormones levels and HBV-DNA load and HBV genotype in HBV-DNA-positive pregnant women. The TSH levels in mid and late pregnancy and TPOAb levels in early, mid, and late pregnancy of HBV-infected pregnant women were higher than those in the same period in HBV-uninfected pregnant women (P < .05). The TPOAb and TGAb levels in early, mid, and late pregnancy of HBV-DNA-positive pregnant women were higher than those in the same period in HBV-DNA-negative pregnant women (P < .05). The HBV-DNA load and FT3 or FT4 levels were negatively correlated (P < .05), and the HBV-DNA load and TGAb levels were positively correlated (P < .05). However, there was no statistical difference in thyroid hormone levels between different HBV genotypes (P > .05). The thyroid hormone levels will change in pregnant women infected with hepatitis B virus, and there is a certain correlation between HBV-DNA load and thyroid hormone levels. Therefore, timely monitoring of thyroid hormones and HBV-DNA load can provide early prevention and treatment for HBV infection in pregnant women, ensuring the health of pregnant women and fetuses.

Neurodevelopmental outcomes of school-age children conceived after hysterosalpingography with oil-based or water-based iodinated contrast: long-term follow-up of a nationwide randomized controlled trial

STUDY QUESTION

Does preconceptional exposure to oil-based iodinated contrast media during hysterosalpingography (HSG) impact children's neurodevelopment compared with exposure to water-based alternatives?

SUMMARY ANSWER

Our study found no large-sized effects for neurodevelopment in children with preconceptional exposure to oil-based iodinated contrast media during HSG compared with water-based alternatives.

WHAT IS KNOWN ALREADY

HSG is widely used as a diagnostic tool in the female fertility work-up. Tubal flushing with oil-based iodinated contrast has been shown to enhance fertility outcomes in couples with unexplained infertility, increasing the chances of pregnancy and live birth compared with water-based alternatives. However, oil-based contrast contains higher doses of iodine and has a longer half-life, and concerns exist that iodinated contrast media can affect women's iodine status and cause temporary (sub)clinical hypothyroidism in mothers and/or foetuses. Considering that thyroid hormones are vital to embryonal and foetal brain development, oil-based contrast media use could increase the risk of impaired neurodevelopment in children conceived shortly after HSG. Here we examine neurodevelopmental outcomes in school-aged children conceived after HSG.

STUDY DESIGN, SIZE, DURATION

This is a long-term follow-up of the H2Oil trial in which oil-based or water-based contrast was used during HSG (Netherlands; 2012-2014; NTR3270). Of 369 children born <6 months after HSG in the study, we contacted the mothers of 140 children who gave consent to be contacted for follow-up. The follow-up study took place from January to July 2022 (NCT05168228).

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

The study included 69 children aged 6-9 years who were conceived after HSG with oil-based (n = 42) or water-based contrast (n = 27). The assessments targeted intelligence (Wechsler Intelligence Scale for Children), neurocognitive outcomes (computerized neurocognitive tests), behavioural functioning (parent and teacher questionnaires), and academic performance. Linear regression models, adjusted for age, sex, and parental educational attainment were employed to compare groups.

MAIN RESULTS AND THE ROLE OF CHANCE

School-aged children born to mothers after oil-based contrast HSG did not significantly differ from children born to mothers after water-based contrast HSG, in regards to intelligence, neurocognitive functioning, behavioural functioning, or academic performance, with the exception of better performance for visuomotor integration functions in children exposed to oil-based contrast preconception. After exploratory correction for multiple comparisons, none of the group differences was statistically significant.

LIMITATIONS, REASONS FOR CAUTION

The small sample size of this follow-up study limited statistical power. This study provides evidence for the absence of large-sized differences between preconceptional exposure to the two contrast media types but does not rule out more subtle effects on neurodevelopment compared to naturally conceived children without preconceptional exposure to HSG.

WIDER IMPLICATIONS OF THE FINDINGS

This study contributes to our knowledge about the long-term effects of different types of iodinated contrast media used in fertility work-up, indicating that choosing oil-based over water-based iodinated contrast media is unlikely to have major effect on the long-term neurodevelopmental outcomes of children conceived shortly after HSG. However, further research should focus on the overall safety of iodine exposure during HSG, comparing children conceived after HSG to those conceived naturally as both types of contrast contain high amounts of iodine.

STUDY FUNDING/COMPETING INTEREST(S)

The original H2Oil randomized controlled trial was an investigator-initiated study that was funded by the two academic hospitals now merged into the Amsterdam University Medical Centre. The current follow-up study (Neuro-H2Oil) is funded through a research grant awarded to the authors by the Amsterdam Reproduction & Development (AR&D) research institute. S.K. is funded by a AMC MD/PhD Scholarship from the Amsterdam UMC. S.K. reports holding voluntary roles in the civil society organizations Universities Allied for Essential Medicines and People's Health Movement. V.M. reports receiving travel and speaker fees as well as research grants from Guerbet, Merck and Ferring. K.D. reports receiving travel and speaker fees as well as research grants from Guerbet. BWM is supported by a NHMRC Investigator grant (GNT1176437) and reports consultancy, travel support and research funding from Merck, consultancy for Organon and Norgine, and holding stock from ObsEva. The other authors report no conflict of interest.

TRIAL REGISTRATION NUMBER

NCT05168228.

Subclinical Hypothyroidism and Thyroid Autoimmunity in Pregnancy: To Treat or Not to Treat

Subclinical hypothyroidism and thyroid autoimmunity in pregnancy are common conditions. They are both associated with adverse maternal and offspring outcomes. Women with thyroid autoimmunity should be monitored with regular thyroid function tests preconception and during gestation to identify women who develop hypothyroidism. The effectiveness of thyroid hormone treatment in reducing adverse outcomes in pregnancy has been studied in a number of randomized controlled trials. Current evidence shows obstetrical benefits of levothyroxine treatment in pregnant women with a thyroid-stimulating hormone level greater than 4 mU/L.

Long-term hypothyroidism in patients started on levothyroxine during pregnancy

Background

Current guidelines recommend different postpartum approaches for patients started on levothyroxine (LT4) during pregnancy.

Objective

We studied the postpartum management of these patients and determined factors associated with long-term hypothyroidism.

Methods

A retrospective study was conducted at a tertiary center between 2014 and 2020, with LT4 initiation according to 2014 ETA recommendations. We performed multivariate logistic regression (MVR) and a receiver operating characteristic curve analysis to determine variables associated with long-term hypothyroidism and their optimal cutoffs.

Results

LT4 was initiated in 177 pregnant women, and 106/177 (60%) were followed at long-term (at least 6 months post partum) (28.5 (9.0-81.9) months). LT4 could have been stopped in 45% of patients who continued it immediately after delivery. Thirty-six out of 106 (34%) patients were long-term hypothyroid. In them, LT4 was initiated earlier during pregnancy than in euthyroid women (11.7 ± 4.7 vs 13.7 ± 6.5 weeks, P = 0.077), at a higher thyroid-stimulating hormone (TSH) level (4.1 (2.2-10.1) vs 3.5 (0.9-6.9) mU/L, P = 0.005), and reached a higher dose during pregnancy (62.8 ± 22.2 vs 50.7 ± 13.9 µg/day, P = 0.005). In the MVR, only the maximal LT4 dose during pregnancy was associated with long-term hypothyroidism (odds ratio (OR) = 1.03, 95% CI: 1.00-1.05, P = 0.003). The optimal cutoffs for predicting long-term hypothyroidism were an LT4 dose of 68.75 µg/day (87% specificity, 42% sensitivity; P = 0.013) and a TSH level ≥ 3.8 mU/L (68.5% specificity, 77% sensitivity; P = 0.019).

Conclusion

One-third of the patients who started on LT4 during pregnancy had long-term hypothyroidism. The TSH level at treatment initiation and the LT4 dose during pregnancy could guide the decision for continuing long-term LT4.

Levothyroxine for subclinical hypothyroidism during pregnancy: an updated systematic review and meta-analysis of randomized controlled trials

PURPOSE

We aimed to perform a systematic review and meta-analysis addressing the efficacy of levothyroxine therapy in pregnant women with subclinical hypothyroidism considering most recent evidence and subgroups of interest for clinical practice.

METHODS

PubMed, Embase, and Cochrane Central were searched from inception for randomized controlled trials (RCTs) comparing levothyroxine with placebo or no intervention in pregnant women with subclinical hypothyroidism. We used a random-effects model and conducted subgroup analyses based on thyroid peroxidase antibody status, thyroid stimulating hormone levels, fertility treatment, and recurrent miscarriage.

RESULTS

We included 11 RCTs comprising 2,749 pregnant women with subclinical hypothyroidism. Patients treated with levothyroxine (1,439; 52.3%) had significantly lower risk of pregnancy loss (risk ratio 0.69; 95% confidence interval 0.52-0.91; p < 0.01; 6 studies). However, there was no significant association between levothyroxine and live birth (risk ratio 1.01; 95% confidence interval 0.99-1.03; p = 0.29; 8 studies). No statistically significant interaction was observed across subgroups (p > 0.05).

CONCLUSION

Levothyroxine replacement therapy for subclinical hypothyroidism during pregnancy may decrease pregnancy loss when early prescribed. Nevertheless, further investigation is needed in patients with thyroid stimulating hormone above four milliunits per liter, especially when associated with recurrent miscarriage or infertility.

Risk Factors for Thyroid Dysfunction in Pregnancy: An Individual Participant Data Meta-Analysis

Background: International guidelines recommend targeted screening to identify gestational thyroid dysfunction. However, currently used risk factors have questionable discriminative ability. We quantified the risk for thyroid function test abnormalities for a subset of risk factors currently used in international guidelines. Methods: We included prospective cohort studies with data on gestational maternal thyroid function and potential risk factors (maternal age, body mass index [BMI], parity, smoking status, pregnancy through in vitro fertilization, twin pregnancy, gestational age, maternal education, and thyroid peroxidase antibody [TPOAb] or thyroglobulin antibody [TgAb] positivity). Exclusion criteria were pre-existing thyroid disease and use of thyroid interfering medication. We analyzed individual participant data using mixed-effects regression models. Primary outcomes were overt and subclinical hypothyroidism and a treatment indication (defined as overt hypothyroidism, subclinical hypothyroidism with thyrotropin >10 mU/L, or subclinical hypothyroidism with TPOAb positivity). Results: The study population comprised 65,559 participants in 25 cohorts. The screening rate in cohorts using risk factors currently recommended (age >30 years, parity ≥2, BMI ≥40) was 58%, with a detection rate for overt and subclinical hypothyroidism of 59%. The absolute risk for overt or subclinical hypothyroidism varied <2% over the full range of age and BMI and for any parity. Receiver operating characteristic curves, fitted using maternal age, BMI, smoking status, parity, and gestational age at blood sampling as explanatory variables, yielded areas under the curve ranging from 0.58 to 0.63 for the primary outcomes. TPOAbs/TgAbs positivity was associated with overt hypothyroidism (approximate risk for antibody negativity 0.1%, isolated TgAb positivity 2.4%, isolated TPOAb positivity 3.8%, combined antibody positivity 7.0%; p < 0.001), subclinical hypothyroidism (risk for antibody negativity 2.2%, isolated TgAb positivity 8.1%, isolated TPOAb positivity 14.2%, combined antibody positivity 20.0%; p < 0.001) and a treatment indication (risk for antibody negativity 0.2%, isolated TgAb positivity 2.2%, isolated TPOAb positivity 3.0%, and combined antibody positivity 5.1%; p < 0.001). Twin pregnancy was associated with a higher risk of overt hyperthyroidism (5.6% vs. 0.7%; p < 0.001). Conclusions: The risk factors assessed in this study had poor predictive ability for detecting thyroid function test abnormalities, questioning their clinical usability for targeted screening. As expected, TPOAb positivity (used as a benchmark) was a relevant risk factor for (subclinical) hypothyroidism. These results provide insights into different risk factors for gestational thyroid dysfunction.

Identifying critical windows of prenatal phenol, paraben, and pesticide exposure and child neurodevelopment: Findings from a prospective cohort study

BACKGROUND

This study aimed to investigate how exposure to a mixture of endocrine disrupting chemicals (EDCs) during two points in pregnancy affects early childhood neurodevelopment.

METHODS

We analyzed publicly-available data from a high-risk cohort of mothers and their children (2007-2014) that measured six EDCs including methyl-, ethyl- and propyl parabens (MEPB, ETPB, PRPB), Bisphenol-A (BPA), 3,5,6-trichloro-2-pyridinol (TCPy), 3-phenoxybenzoic acid (3-PBA) in prenatal urine samples during the second and third trimesters. Neurodevelopmental scores were assessed using Mullen Scales of Early Learning (MSEL) at age 3. We used mean field variational Bayes for lagged kernel machine regression (MFVB-LKMR) to investigate the association between trimester-specific co-exposure to the six EDCs and MSEL scores at age 3, stratified by sex.

RESULTS

The analysis included 130 children. For females, the relationship between BPA and 3PBA with MSEL score varied between the two trimesters. In the second trimester, effect estimates for BPA were null but inversely correlated with MSEL score in the third trimester. 3PBA had a negative relationship with MSEL in the second trimester and positive correlation in the third trimester. For males, effect estimates for all EDCs were in opposing directions across trimesters. MFVB-LKMR analysis identified significant two-way interaction between EDCs for MSEL scores in both trimesters. For example, in females, the MSEL scores associated with increased exposure to TCPy were 1.75 units (95%credible interval -0.04, -3.47) lower in the 2nd trimester and 4.61 (95%CI -3.39, -5.84) lower in the third trimester when PRPB was fixed at the 75th percentile compared to when PRPB was fixed at the 25th percentile.

CONCLUSION

Our study provides evidence that timing of EDC exposure within the prenatal period may impact neurodevelopmental outcomes in children. More of these varying effects were identified among females. Future research is needed to explore EDC mixtures and the timing of exposure during pregnancy to enhance our understanding of how these chemicals impact child health.

The research landscape concerning environmental factors in neurodevelopmental disorders: Endocrine disrupters and pesticides-A review

In recent years, environmental epidemiology and toxicology have seen a growing interest in the environmental factors that contribute to the increased prevalence of neurodevelopmental disorders, with the purpose of establishing appropriate prevention strategies. A literature review was performed, and 192 articles covering the topic of endocrine disruptors and neurodevelopmental disorders were found, focusing on polychlorinated biphenyls, polybrominated diphenyl ethers, bisphenol A, and pesticides. This study contributes to analyzing their effect on the molecular mechanism in maternal and infant thyroid function, essential for infant neurodevelopment, and whose alteration has been associated with various neurodevelopmental disorders. The results provide scientific evidence of the association that exists between the environmental neurotoxins and various neurodevelopmental disorders. In addition, other possible molecular mechanisms by which pesticides and endocrine disruptors may be associated with neurodevelopmental disorders are being discussed.

Gestational thyroid hormones and autism-related traits in the EARLI and HOME studies

Thyroid hormones are essential for neurodevelopment. Few studies have considered associations with quantitatively measured autism spectrum disorder (ASD)-related traits, which may help elucidate associations for a broader population. Participants were drawn from two prospective pregnancy cohorts: the Early Autism Risk Longitudinal Investigation (EARLI), enrolling pregnant women who already had a child with ASD, and the Health Outcomes and Measures of the Environment (HOME) Study, following pregnant women from the greater Cincinnati, OH area. Gestational thyroid-stimulating hormone (TSH) and free thyroxine (FT4) were measured in mid-pregnancy 16 (±3) weeks gestation serum samples. ASD-related traits were measured using the Social Responsiveness Scale (SRS) at ages 3-8 years. The association was examined using quantile regression, adjusting for maternal and sociodemographic factors. 278 participants (132 from EARLI, 146 from HOME) were included. TSH distributions were similar across cohorts, while FT4 levels were higher in EARLI compared to HOME. In pooled analyses, particularly for those in the highest SRS quantile (95th percentile), higher FT4 levels were associated with increasing SRS scores (β = 5.21, 95% CI = 0.93, 9.48), and higher TSH levels were associated with decreasing SRS scores (β = -6.94, 95% CI = -11.04, -2.83). The association between TSH and SRS remained significant in HOME for the 95% percentile of SRS scores (β = -6.48, 95% CI = -12.16, -0.80), but not EARLI. Results for FT4 were attenuated when examined in the individual cohorts. Our results add to evidence that gestational thyroid hormones may be associated with ASD-related outcomes by suggesting that relationships may differ across the distribution of ASD-related traits and by familial likelihood of ASD.

Evaluation of probiotics in the treatment of hypothyroidism in early pregnancy combined with small intestinal bacterial overgrowth

The aim of this study was to investigate the association between hypothyroidism in early pregnancy and small intestinal bacterial overgrowth (SIBO) and the effect of probiotics. Patients with hypothyroidism in early pregnancy and normal pregnant women during the same period were included in the methane-hydrogen breath test to compare the incidence of SIBO, smoothed curve fit, and differences in clinical symptoms. For those who combined with SIBO, the rate of clinical symptom conversion, thyroid hormones, and changes in associated inflammatory indexes were compared after 21 days of treatment with probiotics on top of conventional levothyroxine sodium tablets. The results are as follows: (1) The incidence of combined SIBO in patients with hypothyroidism in pregnancy was 56.0%, significantly higher than the 28.0% of normal pregnant women during the same period. (2) The highest value of hydrogen plus methane gas in 90 min in pregnancy hypothyroid patients showed a significant negative correlation with FT4 (p < .001, SD = 0.169). (3) Abdominal distension symptoms were significantly increased in both groups after combined SIBO (p = .036, p = .025), and the conversion rate after treatment was 69.2% and 75.0%, respectively. (4) In hypothyroidism, pregnancy combined with SIBO, TSH, and CRP was higher before treatment (p = .001, p = .012) and decreased significantly after treatment (p = .001, p = .008). Hypothyroidism in early pregnancy is associated with SIBO, and probiotic treatment is significantly effective.

Lack of beneficiary effect of levothyroxine therapy of pregnant women with subclinical hypothyroidism in terms of neurodevelopment of their offspring

PURPOSE

Despite the beneficial effects of levothyroxine (LT4) therapy on pregnancy outcomes of women with subclinical hypothyroidism (SCH), its impact on the developmental status of offspring remains unclear. We aimed to assess the effects of LT4 therapy on the neurodevelopment of infants of SCH women in the first 3 years of life.

METHODS

A follow-up study was conducted on children born to SCH pregnant women who had participated in a single-blind randomized clinical trial (Tehran Thyroid and Pregnancy Study). In this follow-up study, 357 children of SCH mothers were randomly assigned to SCH + LT4 (treated with LT4 after the first prenatal visit and throughout pregnancy) and SCH-LT4 groups. Children born of euthyroid TPOAb-women served as the control group (n = 737). The neurodevelopment status of children was assessed in five domains (communication, gross motor, fine motor, problem-solving, and social-personal domains) using the Ages and Stages Questionnaires (ASQ) at the age of 3 years.

RESULTS

Pairwise comparisons of ASQ domains between euthyroid, SCH + LT4, and SCH-LT4 groups show no statistically significant difference between groups in the total score [median 25-75 total score: 265 (240-280); 270 (245-285); and 265 (245-285); P-value = 0.2, respectively]. The reanalyzing data using the TSH cutoff value of 4.0 mIU/L indicated no significant difference between groups in the score of ASQ in each domain or total score with TSH levels < 4.0 mIU/L, however, a statistically significant difference in the median score of the gross motor was observed between those SCH + LT4 with baseline TSH values ≥ 4.0 mIU/L and SCH-LT4 [60 (55-60) vs. 57.5 (50-60); P = 0.01].

CONCLUSIONS

Our study does not support the beneficiary effect of LT4 therapy for SCH pregnant women in terms of the neurological development of their offspring in the first three years of life.

Maternal Thyroid Dysfunction During Pregnancy as an Etiologic Factor in Autism Spectrum Disorder: Challenges and Opportunities for Research

Background: Autism spectrum disorder (ASD) is a neurodevelopmental condition with unknown etiology. Both genetic and environmental factors have been associated with ASD. Environmental exposures during the prenatal period may play an important role in ASD development. This narrative review critically examines the evidence for a relationship between maternal thyroid dysfunction during pregnancy and ASD in the child. Summary: Studies that assessed the associations of hypothyroidism, hyperthyroidism, hypothyroxinemia, thyroid hormone concentrations, or autoimmune thyroid disease with ASD outcomes were included. Most research focused on the relationship between hypothyroidism and ASD. Multiple population-based studies found that maternal hypothyroidism was associated with higher likelihood of an ASD diagnosis in offspring. Associations with other forms of maternal thyroid dysfunction were less consistent. Findings may have been affected by misclassification bias, survival bias, or publication bias. Studies using medical records may have misclassified subclinical thyroid dysfunction as euthyroidism. Two studies that assessed children at early ages may have misclassified those with ASD as typically developing. Most studies adjusted for maternal body mass index (BMI) and/or mental illness, but not interpregnancy interval or pesticide exposure, all factors associated with fetal survival and ASD. Most studies reported a combination of null and statistically significant findings, although publication bias is still possible. Conclusions: Overall, evidence supported a positive association between maternal thyroid dysfunction during pregnancy and ASD outcomes in the child, especially for hypothyroidism. Future studies could reduce misclassification bias by using laboratory measures instead of medical records to ascertain thyroid dysfunction and evaluating children for ASD at an age when it can be reliably detected. Survival bias could be further mitigated by adjusting models for more factors associated with fetal survival and ASD. Additional research is needed to comprehensively understand the roles of maternal levothyroxine treatment, iodine deficiency, or exposure to thyroid-disrupting compounds in the relationship between maternal thyroid dysfunction and child ASD outcomes.

Optimizing levothyroxine treatment for subclinical hypothyroidism during pregnancy

The onset of pregnancy places additional stress of the thyroid gland, which must produce additional thyroid hormones to support the developing foetus. Hypothyroidism, including subclinical hypothyroidism (SCH), may appear de novo at this time, or existing thyroid disease may become more severe. Accordingly, SCH is a relatively common complication of up to about 3% of pregnancies, with higher rates in some areas. There is strong evidence from systematic reviews and meta-analyses that uncontrolled SCH is associated with an increased risk of adverse pregnancy outcomes, including miscarriage, preeclampsia, and gestational diabetes. The evidence base also suggests that treatment with levothyroxine (LT4), optimized to control thyrotropin (TSH) to within its pregnancy-specific reference ranges reduces these risks. Current management guidelines provide a clear framework of intervention with LT4 in pregnant women with SCH, especially where TSH is high or where thyroperoxidase autoantibodies are present. Sub-optimal adherence to LT4 is common: it is important that patients take their LT4 correctly and that treating physicians and/or healthcare professionals manage these patients according to the latest management guidelines. The titration of LT4 is likely to occur within a range of LT4 daily doses between 25 µg and 75 µg for the majority of this population. LT4 is a narrow therapeutic index drug and small variations in dosage may produce a clinically significant change in thyroid status. Newer formulations of LT4, engineered to provide more precise and consistent dosing, and with a broad range of tablet strengths, may facilitate the precise titration of the LT4 dose for these patients.

Maternal isolated hypothyroxinemia in the first trimester is not associated with adverse pregnancy outcomes, except for macrosomia: a prospective cohort study in China

Objective

Insufficient thyroid hormone levels during pregnancy, especially in the first trimester, adversely affect maternal and fetal health. However, the impact of isolated hypothyroxinemia (IH) on adverse pregnancy outcomes remains controversial. Therefore, this study aimed to investigate the association between IH during the first trimester and adverse pregnancy outcomes.

Methods

This prospective cohort study included 1236 pregnant women. Thyroid-stimulating hormone and free thyroxine levels were measured before 13 weeks of gestation. Logistic regression analysis and the Cochran-Armitage trend test were used to assess the association between IH in the first trimester and adverse pregnancy outcomes.

Results

IH during the first trimester was associated with an increased risk of macrosomia. After adjusting for confounding factors, including age, body mass index, parity, abnormal pregnancy history, fasting blood glucose, and total cholesterol, multivariate logistic regression analysis showed that IH in the first trimester remained an independent risk factor for macrosomia. In addition, the risk of macrosomia increased with IH severity. However, no significant relationship was found between IH during the first trimester and gestational diabetes mellitus, hypertensive disorders of pregnancy, spontaneous abortion, premature rupture of membranes, placental abruption, oligohydramnios, premature delivery, fetal distress, or low birth weight.

Conclusion

IH during the first trimester did not increase the risk of adverse pregnancy outcomes, except for macrosomia.

Urinary perchlorate, thiocyanate, and nitrate and their associated risk factors among Chinese pregnant women

Perchlorate, nitrate, and thiocyanate are well-known inhibitors of iodide uptake and thyroid-disrupting chemicals. Widespread human exposure to them has been identified, whereas studies on their internal exposure levels among Chinese pregnant women are scarce and factors associated with them are not well recognized. The objective of this study is to determine their levels and identify the associated factors among pregnant women (n = 1120), based on a prospective birth cohort in Wuhan, central China, using repeated urine samples of three trimesters. Urinary perchlorate, thiocyanate, and nitrate were 100% detected in the samples, and specific gravity-adjusted median concentrations of them in all the samples were 12.6 ng/mL, 367 ng/mL, and 63.7 μg/mL, respectively. Their concentrations were weakly-to-moderately correlated with each other, with Spearman correlation coefficients ranging from 0.27 to 0.54. Poor reproducibility were observed for the three analytes over the three trimesters, with intraclass correlation coefficient of 0.07, 0.19, 0.04 for perchlorate, thiocyanate, and nitrate, respectively. The women who were overweight or used tap water as drinking water had significantly higher perchlorate concentrations, while those with excessive gestational weight gain had significantly higher thiocyanate concentrations (p < 0.05). The women with a college degree or above had lower nitrate concentrations (p < 0.05). Meanwhile, the median concentration of perchlorate in urine samples collected in spring, thiocyanate in those collected in winter, and nitrate in those collected in autumn, was significantly higher compared to their median concentrations in the samples collected in other three seasons (p < 0.05), respectively. Urinary perchlorate and nitrate concentrations of pregnant women in this study were higher than the concentrations of pregnant women in other countries, while thiocyanate concentrations were lower than that of most other countries. This study suggested potential covariates for future epidemiological analyses.

Developmental scores in offspring of women with subclinical hypothyroidism in pregnancy are affected by gender and thyrotropin cutoff

OBJECTIVES

Subclinical hypothyroidism (SCH) is defined by elevated thyrotropin (TSH) and normal level of thyroxine (T4). The definition of SCH and the cutoff for TSH normality in pregnancy are debated. In the present study, we assess offspring perinatal outcome, anthropometrics and early development in relation to different TSH levels.

METHODS

An observational study with 77 singleton-pregnant women included by thyroid screening before a planned cesarean section. Two TSH-cutoffs (3.0 and 3.7 mIU/L) defined euthyroid and SCH groups, and were applied to evaluate offspring anthropometrics, complication rates (maternal blood loss, Apgar-score, cord arterial-pH, admission to neonatal intensive care unit, perinatal hypoglycemia) and offspring development. Development was evaluated by Bayley-III test in a subsample at age 6 months (n=27) and 15 months (n=22).

RESULTS

Prevalence of SCH was 31.2 % at TSH-cutoff 3.0 mIU/L, and 16.9 % at TSH-cutoff 3.7 mIU/L. No differences in complications and anthropometrics were observed. In Bayley-III tests, cognitive score was decreased at 6 months (p=0.012) and at 15 months (p=0.056) by applying TSH-cutoff 3.0 mIU/L. At cutoff 3.7 mIU/L, motor score was decreased at 15 months (p=0.020). Male offspring had significantly lower cognitive scores at age 6 and 15 months (TSH-cutoff 3.0 mIU/L), and motor scores at age 15 months (TSH-cutoff 3.7 mIU/L).

CONCLUSIONS

The importance of the definition of thyroid normality in pregnancy is underlined. This study suggests that a gender-effect might be present in maternal thyroid disease, and that developmental differences exist if TSH-cutoff is low. Further research is needed.

Thyroid function test abnormalities-isolated TPOAb+, SCH and hypothyroxinemia and preschool children's neurodevelopment

OBJECTIVE

Thyroid function test abnormalities are frequent and associated with the offspring's adverse neurodevelopment. This study aimed to examine the relationship between maternal thyroid function test abnormalities before 20 gestational weeks and children's cognitive, emotional and behavioural development at 3-6 years of age.

PATIENTS AND MEASUREMENTS

A total of 2243 mother-child pairs were included in the final analysis. Maternal thyroid function was evaluated retrospectively during the children's preschool period. The serum thyrotrophin, free thyroxine and thyroid peroxidase antibodies (TPOAb) were detected by chemiluminescence immunoassay during the follow-up period. The neurodevelopmental status of preschoolers aged 3-6 years was evaluated by parental versions of The Behavior Rating Inventory of Executive Function-Preschool and The Strengths and Difficulties Questionnaires. The associations between maternal thyroid function test abnormalities and preschoolers' neurodevelopment were examined using Poisson regression models.

RESULTS

After adjusting for potential confounders in Poisson regression analyses, it showed that maternal isolated TPOAb positivity before 20 gestational weeks may be associated with the increased risk of abnormalities in peer problems (odds ratio [OR] = 1.90, 95% confidence interval [CI]: 1.26, 287). Maternal isolated SCH before 20 gestational weeks was observed to be related with increased risk of abnormalities in inhibition (OR = 2.73, 95% CI: 1.37, 5.41), working memory (OR = 1.67, 95% CI: 1.04, 2.70), conduct problems (OR = 1.80, 95% CI: 1.05, 3.09), hyperactivity (OR = 1.94, 95% CI:1.08, 3.49) and total difficulties (OR = 1.94, 95% CI: 1.13, 3.34). Maternal isolated hypothyroxinemia before 20 gestational was observed to be related with increased risk of abnormalities in peer problems (OR = 2.71, 95% CI: 1.17, 6.27).

CONCLUSIONS

Thyroid function test abnormalities before 20 gestational weeks may be associated with children's neurodevelopment at 3-6 years of age.

Subclinical hypothyroidism in pregnancy - assessment of offspring thyroid status and mitochondrial robustness to stress

Subclinical hypothyroidism's clinical implications on pregnancy are controversial. Consequently, thyrotropin (TSH) cutoff-values for pregnancy are continuously a subject for debate. In subclinical hypothyroidism, altered levels of thyroid hormones may affect mitochondrial function.Objectives were i) to analyze thyroid hormone levels in offspring of women with and without subclinical hypothyroidism ii) to analyze mitochondrial "robustness" in terms of MTG/TMRM ratio in pregnant women and their offspring in relation to thyroid function and iii) to perform differentiate analyses on different TSH thresholds to determine the importance of cutoff-values to results.Pregnant women were included by blood collections prior to a planned cesarean section, and cord samples were collected after delivery. Thyroid status (analyzed by Siemens Healthcare Diagnostics by an electrochemical luminescent immunoassay based on LOCI-technology) grouped the women and their offspring in euthyroid or subclinical hypothyroid, with groups established from previous recommended third-trimester cutoff-value (TSH > 3.0 mIU/L) and the recently recommended cutoff-value in Denmark (TSH > 3.7 mIU/L). Flow cytometric measurements of mitochondrial function in mononuclear blood cells with the fluorophores TetraMethylRhodamine Methyl Ester (TMRM) and Mitotracker Green (MTG) were used to evaluate mitochondrial robustness as the MTG/TMRM ratio.No significant differences in mitochondrial robustness between euthyroid and subclinical hypothyroid cohorts were observed, irrespective of TSH-cutoff applied. Maternal and cord MTG/TMRM ratios were positively correlated. Cord-TSH was elevated in subclinical hypothyroid offspring, independent of TSH cutoff applied. Cord-TSH was associated with maternal TSH-level, maternal smoking and cord arterial-pH.

[Association of maternal isolated thyroid peroxidase antibody positive in the first trimester with fetal growth]

OBJECTIVE

To investigate the association of isolated thyroid peroxidase antibody (TPOAb) positive in the first trimester with fetal growth.

METHODS

A total of 16 446 pregnant women were included in the birth cohort study, whose last menstrual period was between May 2016 and April 2019 and with singleton pregnancy. Maternal serum samples were collected when they firstly came for prenatal care in the first trimester. The pregnant women were consecutively seen and followed in the hospital and the information of pregnant women was extracted from the electronic medical information system. The pregnant women were divided into isolated TPOAb positive group (n=1 654) and euthyroid group (n=14 792). Three fetal ultrasound examinations were scheduled during the routine prenatal visits at the hospital and were performed by trained sonographers. All fetal growth indicators were quantified as gestational age- and gender- adjusted standard deviation score (Z-score) using the generalized additive models for location, scale and shape (GAMLSS). Fetal growth indicators included estimated fetal weight (EFW), abdominal circumference (AC), biparietal diameter (BPD), femur length (FL) and head circumference (HC). Fetal growth restriction (FGR) was defined as AC or EFW Z-score＜3rd centile based on clinical consensus. Generalized estimating equation (GEE) analysis was applied to assess the association of maternal isolated TPOAb positive with fetal growth. The generalized linear model was further used to analyze the association between isolated TPOAb positive and fetal growth indicator at different gestational ages when the fetal growth indicator was significantly associated with isolated TPOAb positive in the GEE mo-del.

RESULTS

The median gestational age at three ultrasound measurements was 23.6 (23.3, 24.1), 30.3 (29.7, 30.9), 37.3 (37.0, 37.7) weeks, respectively. The BPD Z-score was higher in isolated TPOAb positive women, compared with the euthyroid pregnant women after adjustment (β=0.057, 95%CI: 0.014-0.100, P=0.009). The generalized linear model showed the BPD Z-score was higher in the isolated TPOAb positive women at the end of 21-25 weeks (β=0.052, 95%CI: 0.001-0.103, P=0.044), 29-32 weeks (β=0.055, 95%CI: 0.004-0.107, P=0.035) and 36-40 weeks (β=0.068, 95%CI: 0.011-0.125, P=0.020), compared with the euthyroid pregnant women. There was no difference in other fetal growth indicators (EFW, AC, FL and HC) and FGR between the isolated TPOAb positive and euthyroid pregnant women.

CONCLUSION

The BPD Z-score was slightly increased in the isolated TPOAb positive pregnant women in the first trimester, while other fetal growth indicators were not changed. The reproducibility and practical significance of this result need to be confirmed.

Cetaceans as bio-indicators revealed the increased risks of triclosan exposure and associated thyroid hormone disruption during the COVID-19 pandemic

The global surge in disinfection practices from the COVID-19 response has raised concerns about the marine exposure to the hazardous ingredients in disinfectant products, including triclosan (TCS) and triclocarban (TCC). However, there are very limited studies on the response of marine TCS and TCC (TCs) loading to the COVID-19 pandemic. Here we used cetaceans as bio-indicators for a long-term retrospective analysis of TCs loading to the South China Sea (SCS) between 2004 and 2022. Hepatic TCs was 100% detected in all nine cetacean species (n = 120). Interestingly, TCS concentrations decreased in Indo-Pacific humpback dolphins (IPHD) before the pandemic from 2010 to 2017. However, after 2019, TCS concentrations in IPHD significantly increased several-fold. Similarly, post-pandemic TCS concentrations in Indo-Pacific finless porpoises (IPFP) and two fish species were significantly higher than pre-pandemic levels. There were significant relationships between thyroid hormones (THs) and TCs in IPHD and IPFP, suggesting that increased TCs may worsen the interference of THs homeostasis and nutritional conditions in cetaceans. These findings demonstrate the profound impact of the surging use of TCs-containing products from the COVID-19 response on marine ecosystems.

An update: maternal iodine supplementation, thyroid function tests, and child neurodevelopmental outcomes

PURPOSE OF REVIEW

The impact of maternal iodine supplementation (MIS) during pregnancy on thyroid function and child neurodevelopmental outcomes in areas of mild-to-moderate iodine deficiency (MMID) remains unclear.

RECENT FINDINGS

Despite growing success of salt iodization programs, a 2022 meta-analysis found that 53% of pregnant patients worldwide continue to have insufficient iodine intake during pregnancy. A 2021 randomized controlled trial (RCT) found that MIS in women with mild iodine deficiency led to iodine sufficiency and positive effects on maternal thyroglobulin. A 2021 cohort study of MIS initiated prior to pregnancy was associated with lower thyroid-stimulating hormone (TSH), higher FT3, and FT4. Other cohort studies, however, found that neither salt iodization nor MIS were adequate to meet pregnancy iodine needs. Data have been mixed regarding maternal iodine status and pregnancy outcomes in patients of MMID. Meta-analyses have not shown any clear benefit on infant neurocognitive outcomes with MIS of MMID patients. A 2023 meta-analysis found that the prevalence of excess iodine intake in pregnancy was 52%.

SUMMARY

MMID continues to exist during pregnancy. Salt iodization alone may be insufficient to ensure adequate iodine status during pregnancy. There is an absence of high-quality data to support routine MIS in areas of MMID. However, patients with specialized diets (vegan, nondairy, no seafood, noniodized salt, and so on) may be at risk for inadequate iodine status in pregnancy. Excess iodine intake can be detrimental to the fetus and should be avoided during pregnancy.

Maternal Thyroid Function During Pregnancy and Offspring White Matter Microstructure in Early Adulthood: A Prospective Birth Cohort Study

Background: The fetus is fully dependent on maternal thyroid hormones until mid-gestation and suboptimal maternal thyroid function has been associated with alterations in the neurodevelopment of the offspring. We used maternal free thyroxine (fT4) and thyrotropin (TSH) levels in early gestation to study the association of maternal thyroid function during early pregnancy and offspring brain white matter (WM) integrity in early adulthood. Methods: Our study population consisted of a total of 292 mother-child pairs. Maternal fT4 and TSH were used as predictors and offspring multimodal imaging measures of fractional anisotropy, mean diffusivity, and magnetization transfer ratio (FA, MD, and MTR) as dependent variables. First, as Global analysis, all analyzed 14 WM tracts were studied simultaneously using linear-mixed effect models. Second, if a global effect was detected, a post hoc Tract-wise analysis was carried out using linear models individually in each WM tract. Study population was stratified by sex. Results: We found a positive association between maternal fT4 and offspring Global FA in males when adjusted for all maternal and offspring covariates (n = 114; β = 0.154; confidence interval = 0.045-0.263; p = 0.006). The finding was observed to be driven by multiple WM tracts, of which three projection fiber tracts and the forceps minor survived correcting for multiple comparisons in Tract-wise analysis. Conclusions: Maternal thyroid function in early pregnancy was observed to be associated with WM microstructure in male offspring in early adulthood. Our results suggest that maternal fT4 levels in early pregnancy may modulate axonal characteristics, with a long-term effect on offspring WM development.

The Impact of Subclinical Hypothyroidism on the Quality of Life During Pregnancy: Mapping 5-Level Version of EQ-5D and ThyPRO-39

OBJECTIVES

To describe how subclinical hypothyroidism (SubHypo) influences the quality of life (QoL) during pregnancy.

METHODS

In primary data collection (NCT04167423), thyroid stimulating hormone (TSH), free thyroxine (FT4), thyroid peroxidase antibodies, generic quality of life (QoL; 5-level version of EQ-5D [EQ-5D-5L]), and disease-specific QoL (ThyPRO-39) were measured among pregnant women. SubHypo during each trimester was defined according to the 2014 European Thyroid Association guidelines (TSH > 2.5, 3.0, and 3.5 IU/L, respectively; with normal FT4). Path analysis described relationships and tested mediation. Linear ordinary least squares, beta, tobit, and two-part regressions were used to map ThyPRO-39 and EQ-5D-5L. Alternative SubHypo definition was tested in sensitivity analysis.

RESULTS

A total of 253 women at 14 sites (31 ± 5 years old, 15 ± 6 weeks pregnant) completed the questionnaires. Sixty-one (26%) had SubHypo and differed from 174 (74%) euthyroid women in smoking history (61% vs 41%), primiparity (62% vs 43%) and TSH level (4.1 ± 1.4 vs 1.5 ± 0.7 mIU/L, P < .001). EQ-5D-5L utility in SubHypo (0.89 ± 0.12) was lower than that in euthyroid (0.92 ± 0.11; P = .028) even after adjustment (difference -0.04, P = .033), whereas ocular (P = .001, ThyPRO-39), cognitive symptoms (P = .043), anxiety (P < .0001), and the composite score were higher. The impact of SubHypo on utility was mediated by anxiety. Results were confirmed by sensitivity analysis. Final mapping equation (ordinary least squares) includes goiter symptoms, anxiety, upset stomach, composite score (ThyPRO-39), FT4 levels, and week of pregnancy (determination coefficient 0.36).

CONCLUSION

This is the first QoL mapping of SubHypo during pregnancy and the first evidence that SubHypo is associated with a negative impact on QoL. The effect is mediated by anxiety. EQ-5D-5L utilities can be generated based on ThyPRO-39 scores collected in pregnant euthyroid and patients with SubHypo.

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".

Sex-specific neurobehavioral and prefrontal cortex gene expression alterations following developmental acetaminophen exposure in mice

Acetaminophen (N-acetyl-p-aminophenol (APAP), also known as paracetamol) is one of the most common medications used by the general population, including pregnant people. Although many human observational and animal model studies have shown associations between prenatal and early postnatal APAP exposure and attention deficit hyperactivity disorder, autism spectrum disorders, and altered neurodevelopment, the existing literature is limited. In particular, no mouse studies of prenatal APAP exposure have investigated offspring attention deficits in behavioral tasks specifically designed to measure attention, and no prior rodent studies have utilized 'omics' technologies, such as transcriptomics, for an untargeted exploration of potential mechanisms. We randomly assigned pregnant mice (starting embryonic day 4-10) to receive APAP (150 mg/kg/day) or vehicle control through postnatal day 14. We evaluated 111 mouse offspring in a battery of behavioral tests, including pup ultrasonic vocalizations, elevated plus-maze, open field test, CatWalk (gait), pre-pulse inhibition, and the automated 5-choice serial reaction time task. Prefrontal cortex was collected at birth from 24 pups for RNA sequencing. Developmental APAP treatment resulted in increased and hastened separation-induced pup vocalizations between postnatal days 2 and 11, as well as decreased ambulation and vertical rearings in the open field in male but not female adult offspring. APAP treatment was also associated with altered sex-specific prefrontal cortex gene expression relating to glutathione and cytochrome p450 metabolism, DNA damage, and the endocrine and immune systems. This study provides additional evidence for the neurodevelopmental harm of prenatal APAP exposure and generates hypotheses for underlying molecular pathways via RNA sequencing.

Bisphenol A alternatives continuously contribute to the endocrine disruption in cetaceans

The bans on bisphenol A (BPA) have facilitated the widespread use of BPA alternatives and shifted environmental contamination profiles of bisphenols (BPs). However, the continued reports of toxicities of emerging BPA alternatives have raised questions about whether the shifting profiles are contributed to mitigate BPs-mediated endocrine-disruption effects (EDEs). Cetaceans are commonly used as the ideal sentinel species for monitoring marine pollutants of concern and determining potential health effects, but far less is known about BP loads and BPs-mediated EDEs in cetaceans. Here we measured the hepatic concentrations of six BPs in eight stranded cetacean species (n = 41) in the South China Sea, between 2007 and 2020. The large-bodied whales generally showed higher ∑BPs concentrations than the small-bodied dolphins. In Indo-Pacific finless porpoises (Neophocaena phocaenoides) (n = 33), BPA concentrations first increased (2007-2014) and then decreased (2014-2020), while ∑BP_Alternatives concentrations increased from 2007 to 2020. It appears that the alternatives gradually replaced BPA, probably due to the BPA-related bans in China. In order to examine the hormone disruption of BPA and its alternatives in finless porpoises, five blubber hormones (cortisol, progesterone, testosterone, triiodothyronine and tetraiodothyronine), which are proven to be validated endocrine biomarkers, were measured in 21 samples. Tetraiodothyronine, testosterone, and cortisol were significantly and positively correlated with BPA and its alternatives, suggesting that the interference of endocrine hormone homeostasis may continue to occur despite the changes of BP profiles in finless porpoises. This is the first investigation of the relationship between hormone and BP concentrations in cetaceans and represents a substantial advance in understanding BPs-mediated endocrine effects on cetaceans.

Association of exposure to ambient particulate matter with maternal thyroid function in early pregnancy

BACKGROUND

It is known that maternal thyroid dysfunction during early pregnancy can cause adverse pregnancy complications and birth outcomes. This study was designed to examine the association between ambient particulate matter with aerodynamic diameters ≤2.5 μm (PM2.5) and particulate matter with aerodynamic diameters ≤10 μm (PM10) exposure and maternal thyroid function during early pregnancy.

METHODS

This study was based on data from a birth cohort study of 921 pregnant women in China. We estimated associations between ambient PM2.5 and PM10 exposure during the first trimester of pregnancy (estimated with land-use regression models) and maternal thyroid hormone concentrations (free thyroxine (FT4), free tri-iodothyronine (FT3), and thyroid-stimulating hormone (TSH)) collected between weeks 10 and 17 of gestation using linear regression models adjusting for potential confounders. Ambient PM2.5 and PM10 concentrations were modeled per interquartile range (IQR) increment and as tertiles based on the distribution of the exposure levels.

RESULTS

An IQR increment (68 μg/m3) in PM2.5 exposure was associated with a significant decrease in maternal FT4 levels (β = -0.60, 95% CI: -1.07, -0.12); and a significant decrease in FT4/FT3 ratio (β = -0.13, 95% CI: -0.25, -0.02). Further analyses showed that, relative to the lowest tertile, women in both the middle and highest tertiles of PM2.5 had significantly lower concentrations of maternal FT4 and FT4/FT3 ratio. No significant associations were found between PM2.5 and FT3 or TSH levels. PM10 exposure was not significantly associated with maternal thyroid function.

CONCLUSIONS

Our study suggested that higher ambient PM2.5, not PM10, exposed during the first trimester of pregnancy were associated with a significant decrease in maternal serum FT4 concentrations and FT4/FT3 ratio. Studies in populations with different exposure levels are needed to replicate our study results.

Pregnancy hypothyroidism incidence and complications using the 2011 and 2017 ATA cutoff values. Experience at a maternity hospital in a densely populated area in Mexico City

OBJECTIVES

Normal thyroid activity has an essential role in fetal development, its deficiency may hamper fetal neurodevelopment and neonatal growth. The quantitation of thyroid hormones although useful, still exposes differences on cut off levels to diagnose thyroid deficit accurately that can elicit under or over diagnosis of thyroid dysfuntion.

METHODS

A total of 839 pregnant patients were studied for thyroidal clinical assessment through quantitation of thyroid-stimulating hormone (TSH) and free thyroxine (FT4) circulating levels. Patients evaluated for prenatal and neonatal outcomes. Thyroid function deficiencies were determined with the American Thyroid Association (ATA) 2011 and 2017 values. Statistical analysis searched for associations between variables, odds ratios (OR) and correlations were calculated to evaluate the reliability of the cutoff values recommended by the ATA.

RESULTS

Mean age of our cases was 27.5 + 5.83 years at diagnosis, mean gestational age at first consultation was 23.8 + 10.5 weeks. Mean TSH levels detected were: 2.5 + 1.89 mIU/L, total T3: 3.55 + 4.1 ng/dL, FT4: 3.14 + 4.4 ng/dL. The ATA 2011 values yielded 332 hypothyroidism cases vs. 507 euthyroid patients, a total incidence of 39.6% vs. the ATA 2017 values, diagnosing 100 hypothyroidism cases and 739 euthyroid patients, total incidence of 11.9%. Association with complications were not significant.

CONCLUSIONS

Using ATA 2017 values showed a decreased population with gestational hypothyroidism, hence preventing overdiagnosis and over-treatment. No significant complications were associated, requiring the determination of new regional values. Education and sensibilization of our population is needed to comply with early prenatal consultation and thyroid function testing.

Under and overtreatment with thyroid hormone replacement during pregnancy

PURPOSE OF REVIEW

Among pregnant women on thyroid hormone replacement therapy undertreatment is common, while overtreatment is rare. Both deficient and excessive maternal thyroid hormone have been related to adverse maternofetal and long-term offspring outcomes, although studies' results are inconsistent. This review aims to discuss recent evidence regarding the effects of under- and overtreatment with thyroid hormone replacement during pregnancy and how current practices could be improved.

RECENT FINDINGS

Whether or not thyroid hormone therapy needs to be initiated for maternal subclinical hypothyroidism remains unclear, but recent meta-analyses have confirmed associations between adverse maternal, neonatal, and offspring outcomes in both overt and subclinical hypothyroidism. Subclinical hyperthyroidism in pregnancy is related to fewer adverse outcomes. Current adherence to levothyroxine during pregnancy and medication counseling by healthcare providers are suboptimal.

SUMMARY

Undertreatment of maternal hypothyroidism may increase risks for adverse maternofetal and offspring effects more than overtreatment does. If thyroid hormone replacement therapy is indicated and initiated in pregnancy, frequent thyroid function monitoring is required to avoid under- or overtreatment. Effective communication between clinicians and patients is imperative to increase medication adherence.

Effect of Bushen Antai recipe on pyroptosis mechanism of subclinical hypothyroidism decidual cells in early pregnancy

BACKGROUND

Subclinical hypothyroidism (SH) is common during pregnancy. It is not clear whether decidual cells in SH undergo pyroptosis during pregnancy. This study aimed to investigate the possible mechanism of Bushen Antai recipe (BAR) in the treatment of SH in early pregnancy and the relationship between SH during pregnancy and decidual cell pyroptosis through a rat model.

METHODS

A total of 60 female rats were divided into control group, model group, levothyroxine (L-T4) group, low-dose BAR group (6 g/kg), medium-dose BAR group (12 g/kg), and high-dose BAR group (24 g/kg). The control group underwent pseudothyroidectomy, while the remaining groups established nonpregnant SH rat models. Except for the blank control group, rats were successfully established with SH models during pregnancy. The control group and the model group were treated with saline or BAR. The animals were sacrificed 12 hours after the last administration. The levels of serum thyroid-stimulating hormone (TSH), free thyroxine (FT4), interleukin-1β (IL-1β), and interleukin-18 (IL-18) were detected by enzyme-linked immunosorbent assay (ELISA). Western blot was used to detect the expression of decidual nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome, Caspase-1, and porin family proteins.

RESULTS

There was no significant difference in serum FT4 among groups (P>0.05). Compared with the control group, serum TSH, IL-1β, IL-18, and NLRP3, Caspase-1, and gasdermin D (GSDMD) proteins in the decidua of the model group were significantly increased (P<0.05). Compared with the model group, the L-T4 group and the high-dose BAR group could significantly decrease the levels of serum TSH, IL-1β, IL-18, and NLRP3, Caspase-1, and GSDMD in decidual tissue (P<0.05). The medium dose of BAR could significantly decrease the levels of TSH, NLRP3, Caspase-1, and GSDMD (P<0.05), and the low dose group of BAR significantly decreased the levels of TSH, NLRP3, and GSDMD (P<0.05). Among them, the high-dose group of BAR had the best reducing effect on IL-18, NLRP3, Caspase-1, and GSDMD.

CONCLUSIONS

The decidual cells of SH rats in early pregnancy underwent pyroptosis with a high inflammatory response. BAR could improve TSH level in SH during pregnancy, inhibit decidual cell pyroptosis, and reduce the expression of inflammatory factors.

Late offspring effects of antenatal thyroid screening

BACKGROUND

Thyroid dysfunction in pregnancy is associated with adverse offspring outcomes and recent birth-cohort studies suggest that even mild degrees of thyroid dysfunction may be linked with a range of late cognitive and behavioural effects in childhood and adolescence.

SOURCES OF DATA

This review summarizes recent literature of observational studies and critically appraises randomized controlled trials (RCTs) of antenatal thyroid screening and Levothyroxine intervention.

AREAS OF AGREEMENT

Overt hypothyroidism and hyperthyroidism carry significant risks for unfavourable offspring outcomes and should be appropriately corrected in pregnancy.

AREAS OF CONTROVERSY

The significance of subclinical hypothyroidism and hypothyroxinaemia is still unclear. Meta-analyses of birth-cohort studies show associations of maternal subclinical hypothyroidism and hypothyroxinaemia with intellectual deficits, attention deficit hyperactivity disorder (ADHD) and autism spectrum disorders, while hyperthyroidism and high-normal FT4 were linked with ADHD. RCTs have shown no benefits of screening on neurodevelopmental outcomes although Levothyroxine could have been initiated too late in pregnancy in these trials.

GROWING POINTS

A small number of studies have shown inconsistent associations of maternal thyroid dysfunction with offspring cardiometabolic indices including blood pressure and body weight. Correction of maternal thyroid dysfunction was, however, associated with favourable long-term metabolic profiles in mothers, including lipid profiles, fat mass and body mass index. Antenatal thyroid screening may therefore present opportunities for optimizing a wider range of outcomes than envisaged.

AREAS FOR DEVELOPING RESEARCH

Future trials with early antenatal thyroid screening and intervention are necessary to clarify the impact of screening on late offspring and maternal effects.

Preconception Counseling in Patients with Hypothyroidism and/or Thyroid Autoimmunity

Preconception counseling is an essential tool for preventing adverse pregnancy outcomes associated with thyroid dysfunction. The high prevalence of thyroid disease among women of reproductive age, and the increased risk of adverse pregnancy outcomes associated with thyroid dysfunction, emphasize the necessity for well-established screening and treatment criteria in the preconception period. We therefore conducted a literature review for relevant information on the screening, diagnosis and treatment of subclinical and overt hypothyroidism in women seeking pregnancy. While screening for thyroid disease is recommended only in the presence of risk factors, iodine supplementation should be recommended in most regions, with higher doses in areas with severe deficiency. Known hypothyroid women should be counseled about increasing their levothyroxine dose by 20–30% in the case of suspected or confirmed pregnancy (missed menstrual cycle or positive pregnancy test). Treating subclinical hypothyroidism appears to be beneficial, especially in the presence of autoimmunity or in patients undergoing artificial reproductive techniques. Regarding the management of TPOAb negative SCH women or euthyroid women with positive TPOAb, further research is necessary in order to make evidence-based recommendations.

Exposure to perfluoroalkyl substances and neurodevelopment in 2-year-old children: A prospective cohort study

BACKGROUND

Humans are widely exposed to per- and polyfluoroalkyl substances (PFAS). As fetal stage is a critical window for neurodevelopment, it is important to know if in utero exposure to PFAS affects fetal neurodevelopment. However, previous human studies are both limited and inconsistent.

OBJECTIVES

To investigate the relationship between PFAS exposure during early pregnancy and the neurodevelopmental status at 2 years of age in a prospective cohort study.

METHODS

We measured 10 PFAS in maternal plasma samples collected prior to 16 weeks of gestation in the Shanghai Birth Cohort Study between 2013 and 2016. Childhood neurodevelopment was assessed at 2 years of age using the Bayley Scales of Infant and Toddler Development-Third Edition (BSID-III). Associations with domain specific scores for individual PFAS were assessed by multiple linear regression and binary logistic regression when scores were dichotomized. Quantile-based g-computation was used to estimate the joint effects of PFAS mixture.

RESULTS

A total of 2257 mother-child pairs who had both PFAS and BSID measurements were included in our analyses. The means and standard deviations of comprehensive scores were 115 ± 22, 96 ± 15 and 108 ± 15 for cognition, language, and motor, respectively. In multiple linear regressions, we observed significant negative associations of perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDeA), perfluoroundecanoic acid (PFUnDA) with cognitive scores; PFNA, PFDeA, PFUnDA and perfluorohexanesulfonate (PFHxS) negatively with language scores; and PFNA and PFUnDA negatively with motor scores. Quantile-based g-computation showed that PFAS mixture was significantly associated with decreased cognitive and language scores, with an estimated β of -2.1 [95% confidence interval (CI): -3.5, -0.7)] and -2.0 (95% CI: -2.9, -1.0) per one quartile increase in PFAS mixture for cognitive and language domains, respectively. PFAS mixture was associated with increased odds of low cognition (adjusted odds ratio [OR] = 1.3, 95% CI:1.0, 1.6) and language scores (OR = 1.2, 95% CI: 1.1, 1.3).

CONCLUSIONS

PFAS exposure during early pregnancy was significantly associated with the adverse neurodevelopmental status at 2 years of age, which raises a serious public health concern.

Hypothyroidism And Gestational Diabetes Mellitus: Is There A Relationship?

Background and Objective — Subclinical gestational hypothyroidism (SGH) and gestational diabetes mellitus (GDM) constitute two most common endocrine pathologies encountered during pregnancy. SGH and GDM have common pathophysiological mechanisms, being interrelated pathological conditions that are capable of complicating the course of pregnancy, labor and the postpartum period both on the part of the mother and on the part of the fetus. We aimed to analyze the relationship between these pathologies and to assess the risk of developing GDM against the background of hypothyroidism. Materials and Methods — the study included 200 pregnant women observed at the Perinatal Center of the Maternity Hospital the Bauman State Clinical Hospital No. 29 during 2018-2020. The main group consisted of 133 women who visited the perinatal center for hypothyroidism (both SGH and primary hypothyroidism, detected prior to pregnancy); the control group comprised 67 women without endocrine pathology. Both groups were comparable in terms of age, height, weight, and the number of pregnancies in the anamneses. The main group received levothyroxine sodium therapy with the achievement of the target trimester-specific level of thyroid-stimulating hormone (TSH). The criteria for the diagnosis of SGH were the TSH level above 2.5 μIU/mL in combination with an enlarged titer of antithyroid antibodies and/or a burdened medical history of thyroid pathology, or the TSH level above 4.0 μIU/mL in the absence of antithyroid antibodies [1]. The diagnosis of GDM was established on the basis of fasting hyperglycemia (≥5.1 mmol/L), or based on the results of an oral glucose tolerance test (OGTT) with 75 g of glucose: fasting glucose level of ≥5.1 mmol/L; the concentration 1 hour after glucose intake ≥10.0 mmol/L; the content 2 hours after glucose intake ≥8.5 mmol/l) [2]. In both groups, the frequency of developing GDM, the timing of diagnosis, and the need for insulin therapy were evaluated. Statistical data processing was carried out using the StatTech v. 2.1.0 software. Quantitative indicators were assessed for compliance with the normal distribution via Shapiro-Wilk criterion or Kolmogorov-Smirnov criterion. Intergroup comparison was performed using Mann-Whitney U test or Pearson’s chi-squared test. Results — We discovered that among women with a burdened family history of thyroid pathology and diabetes mellitus, as well as with thyroid pathology prior to pregnancy, the prevalence of hypothyroidism was higher. The presence of thyroid pathology in the anamnesis of pregnant women was associated with an earlier diagnosis of hypothyroidism. We revealed a significant difference in the prevalence of GDM between two groups of subjects. The chances of detecting GDM in the hypothyroidism group were 8.6 times higher than in the euthyroidism group. The threshold level of TSH for the first trimester, predicting the development of GDM, was identified. The sensitivity and specificity of the model were 71.4% and 63.1%, respectively. Conclusion — Hypofunction of the thyroid and GDM are interrelated endocrine pathologies. In the presence of hypothyroidism (both primary and SGH), GDM develops significantly more often. The level of TSH in the first trimester ≥2.7 μIU/mL amplifies the chance of developing GDM by over 8 times; hence, it could be considered a signal for timely prevention and detection of this pathology.

Management of Hypothyroidism and Hypothyroxinemia in Pregnancy

OBJECTIVE

To review the diagnosis and management of hypothyroidism in pregnancy, preconception, and the postpartum period.

METHODS

Literature review of English-language papers published between 1982 and 2022, focusing on the most recent literature.

RESULTS

During pregnancy, thyroid function laboratory tests need to be interpreted with regard to gestational age. Overt hypothyroidism, regardless of the TSH level, should always be promptly treated when it is diagnosed preconception or during pregnancy or lactation. Most women with preexisting treated hypothyroidism will require an increase in levothyroxine dosing to maintain euthyroidism during gestation. levothyroxine-treated pregnant patients need close monitoring with serum thyroid stimulating hormone (TSH) to avoid or- or under treatment. There is no consensus about whether to initiate levothyroxine in women with mild forms of gestational thyroid hypofunction. However, in light of current evidence it is reasonable to treat subclinically hypothyroid women with levothyroxine, particularly if the TSH is >10 mIU/L or the thyroperoxidase antibody is positive. Women who are not treated need to be followed to ensure that treatment is initiated promptly if thyroid failure progresses. Additional studies are needed to better understand the effects of the initiation of levothyroxine in early gestation in subclinically hypothyroid and hypothyroxinemic women and to determine optimal strategies for thyroid function screening in preconception and pregnancy.

CONCLUSION

The diagnosis and management of hypothyroidism in the peripregnancy period present specific challenges. In making management decisions, it is essential to weigh the risks and benefits of treatments not just for the mother but also for the fetus.