Childhood IQ, hearing loss, and maternal thyroid autoimmunity in the Baltimore Collaborative Perinatal Project

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.

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.

Iodine status during child development and hearing ability: a systematic review

Iodine, through the thyroid hormones, is required for the development of the auditory cortex and cochlea (the sensory organ for hearing). Deafness is a well-documented feature of endemic cretinism resulting from severe iodine deficiency. However, the range of effects of suboptimal iodine intake during auditory development on the hearing ability of children is less clear. We therefore aimed to systematically review the evidence for the association between iodine exposure (i.e. intake/status/supplementation) during development (i.e. pregnancy and/or childhood) and hearing outcomes in children. We searched PubMed and Embase and identified 330 studies, of which thirteen were included in this review. Only three of the thirteen studies were of low risk of bias or of good quality, this therefore limited our ability to draw firm conclusions. Nine of the studies (69 %) were in children (one RCT, two non-RCT interventions and six cross-sectional studies) and four (31 %) were in pregnant women (one RCT, one cohort study and two case reports). The RCT of iodine supplementation in mildly iodine-deficient pregnant women found no effect on offspring hearing thresholds. However, hearing was a secondary outcome of the trial and not all women were from an iodine-deficient area. Iodine supplementation of severely iodine-deficient children (in both non-RCT interventions) resulted in improved hearing thresholds. Five of six cross-sectional studies (83 %) found that higher iodine status in children was associated with better hearing. The current evidence base for the association between iodine status and hearing outcomes is limited and further good-quality research on this topic is needed.

The findings about relationship between autoimmune thyroid disease and first-trimester aneuploidy results

Aim: The aim of this study was to investigate the relationship between thyroid autoantibody and first-trimester aneuploidy results. Thyroid autoimmunity (TAI) is the most common autoimmune disorder. Patients with TAI are usually euthyroid. Thyroid peroxidase (TPO-Ab) in patients with or without thyroid dysfunction is associated with infertility, recurrent embryo implantation failure, and early pregnancy loss. The impact of TPO-Ab on first-trimester aneuploidy test results needs to be studied. Material and Method: This retrospective case-control study was conducted between December 2019 and May 2022. Patients with thyroid autoantibody positivity (n=112) were included in the study as the case group. The control group was selected from age and body mass index (BMI)-matched patients (n=130). Nuchal translucency (NT), crown rump length (CRL), pregnancy-associated plasma protein A (PAPP-A) and free beta subunit of human chorionic gonadotropin (β-hCG)) values were compared between the two groups. Results: This study included two hundred forty two age-matched (29.86±4.51) and BMI-matched (23.96±2.34) women. There was no statistically significant difference between groups in terms of free thyroxine (FT4), PAPP-A and free β-hCG (p>0.05). NT as a marker for major chromosomal defects and CRL were comparable in case and control groups (p>0.05). Conclusion: There is no statistically significant relationship between thyroid autoimmune diseases and the first-trimester aneuploidy results.

Sex-Specific Effect of Thyroid Peroxidase Antibody and Thyroglobulin Antibody Exposure During Pregnancy on Preschoolers' Emotional and Behavioral Development: A Birth Cohort Study

Background: Epidemiological and experimental studies suggest that thyroid peroxidase antibody (TPOAb)- and thyroglobulin antibody (TGAb)-positive exposure during gestation may contribute to offspring's adverse neural development. However, limited knowledge is available on the association between joint exposure on TPOAb and TGAb and children's emotional and behavioral development. Furthermore, the sex-specific effect on the developmental process of preschoolers' emotions and behaviors is unknown. The present research intends to examine the sex-specific effect of TPOAb- and TGAb-positive exposure in gestation on the developmental process of preschoolers' emotions and behaviors. Methods: A total of 2455 mother-child pairs were included from the Ma'anshan Birth Cohort study. The serum TPOAb and TGAb of pregnant women was measured retrospectively by electrochemical immunoassay during the follow-up period. Preschoolers' emotional and behavioral development was assessed by a child behavior checklist 1.5-5. Growth mixture modeling was adopted to fit thyroid antibody (TAb) trajectories. Poisson regression models were used, stratifying by sex, to examine the association between TAb trajectories, as well as four categories of maternal TAb exposure and preschoolers' emotional and behavioral problems. Results: Boys born to mothers with TPOAb positivity in the first, second, and third trimesters of pregnancy had an increased risk of autism spectrum problems after adjusting for confounders, with relative risk (RR) [confidence interval, CI] of 2.01 [1.24-3.27], 2.15 [1.08-4.26], and 2.13 [1.20-3.79], respectively. Maternal TGAb positivity and TPOAb negativity in the first trimester were associated with a high risk of attention-deficit/hyperactivity problems in boys (RR = 1.74 [CI 1.01-2.99]). The prevalence of depressive problems in girls was 33.3% after exposure to TPOAb alone in the third trimester of pregnancy. Exposure to TPOAb alone in the third trimester of pregnancy was associated with an increased risk of depressive problems in girls (RR = 1.78 [CI 1.09-2.90]). Conclusions: Maternal TPOAb positivity in all three trimesters was associated with the risk of autism spectrum problems in boys. Isolated maternal TGAb positivity in the first trimester was associated with attention-deficit/hyperactivity problems in boys, whereas isolated maternal TPOAb positivity in the third trimester was associated with depressive problems in girls.

Euthyroid Thyroperoxidase Antibody Positivity during Pregnancy, to Treat or Not to Treat?

Thyroperoxidase antibody (TPOAb) positivity is a well-known risk factor for thyroid dysfunction during pregnancy and is associated with a suboptimal response to thyroidal stimulation by human chorionic gonadotropin. About 75% of TPOAb positive women are euthyroid and there seems to be a higher risk of predominantly miscarriage and preterm birth in this subgroup. Nonetheless, clinical decision making with regards to gestational levothyroxine treatment remains difficult due to a lack of large randomized trials. Future studies assessing dose-dependent associations and additional biomarkers that can distinguish low-risk from high-risk individuals will be key in disentangling the crude clinical data.

Subclinical Hypothyroidism with Negative for Thyroid Peroxidase Antibodies in Pregnancy: Intellectual Development of Offspring

Background: The adverse impact of maternal negative TPOAb of gestational subclinical hypothyroidism (SCH-TPOAb^-) on the development of the offspring has not yet been clearly identified. A lingering controversy exists over the treatment of SCH-TPOAb^- diagnosed during pregnancy. Therefore, this study was designed to evaluate the intellectual development of children of mothers who had SCH-TPOAb^-. Methods: A number of 139 children were recruited; 112 children were born to SCH TPOAb^- and 27 children were born to euthyroid TPOAb^- mothers. Based on the mothers' thyrotropin (TSH) levels during pregnancy and whether or not they received levothyroxine (LT4) treatment, the children were assigned to four groups: Group A (2.5 mIU/L < TSH ≤4.0 mIU/L, n = 31) and Group B (4.0 mIU/L < TSH ≤10.0 mIU/L, n = 26), whose mothers were treated with LT4 before eight gestational weeks, and Group C (2.5 mIU/L < TSH ≤4.0 mIU/L, n = 27) and Group D (4.0 mIU/L < TSH ≤10.0 mIU/L, n = 28), whose mothers received no treatment. A total number of 27 children whose mother's serum TSH was <2.5 mIU/L and were TPOAb^- during their pregnancy served as the control group (Group E). The intellectual development of two-year-old children was assessed and compared using the Gesell Development Diagnosis Scale. Results: The developmental quotient (DQ) in Group D was 8.67 lower than this in Group E (p < 0.001). More specifically, gross motor quotient, fine motor quotient, adaptability quotient (ABQ), language quotient (LQ), and individual social behavior quotient (ISBQ) of DQ in Group D were significantly lower than those in Group E. No significant differences were observed in DQ among Group A, Group B, Group C, and Group E (p > 0.05). Spearman's rank correlation analysis showed that DQ, FMQ, ABQ, LQ, and ISBQ were significantly negatively correlated with the TSH level (r = -0.417, -0.253, -0.273, -0.436, and -0.272; p < 0.05). In addition, multivariate logistic regression analysis revealed that mothers' education (short education), mothers' education (medium education), and TSH level (4.0 mIU/L < TSH ≤10.0 mIU/L) were both risk factors affecting the intellectual development of the offspring (p < 0.05). Conclusion: The effects of the intellectual development of the offspring with SCH-TPOAb^- are related to the level of TSH. Standardized treatment for SCH-TPOAb^- pregnant women before eight gestational weeks, whose TSH level was from 4.0 to 10.0 mIU/L, may significantly improve the intellectual development levels of the approximately two-year-old offspring. Although our study was a historical cohort study, the data analyzed provide the foundation for further investigation. Further prospective intervention trials with large numbers of participants are needed to confirm our conclusions. The Clinical Trial Registration number is 2021-K-84-02.

TPO antibody in euthyroid pregnant women and cognitive ability in the offspring: a focused review

PURPOSE

A link between maternal thyroid dysfunction during pregnancy and the risk of cognitive and behavioral problems in the offspring has previously been established; however, the potential effects of maternal thyroid autoimmunity on neurodevelopment in the absence of maternal hypothyroidism are less clear. The present review aims to highlight the gaps in knowledge in this regard and provide a thorough assessment of relevant literature.

METHOD

Related keywords searched in MEDLINE, Web of Science, and Scopus till January 2021.

RESULTS

There is some evidence that neuropsychological and intellectual developments of offspring are adversely affected by maternal thyroid autoimmunity, although the results of available studies are not concordant. The tools and measurements that have been applied in different studies to assess neurodevelopment or IQ vary widely and the children born to mothers with thyroid autoimmunity have been assessed at different chronological stages of life. Such variations may explain some of the differences across studies. In addition, the definition of thyroid autoimmunity has been based on TPOAb cut points provided by manufacturers in most cases, but it is preferable to define these values based on age, trimester, and method-specific reference ranges.

CONCLUSION

Well-designed studies are needed to assess verbal and non-verbal neurocognition of offspring born to mothers with autoimmune thyroid disease before or during pregnancy.

Thyroid Autoimmunity in Adverse Fertility and Pregnancy Outcomes: Timing of Assisted Reproductive Technology in AITD Women

Thyroid autoimmunity (TAI) is prevalent in women of live-birthing age and has independently been associated with complications of fertility and pregnancy, in the case of spontaneous conception or after assisted reproductive technology (ART) treatment. However, it remains challenging to identify causation between infertility and TAI, even interventional trials looking at the impact of levothyroxine (LT4) treatment on fertility and pregnancy outcomes due to differences among study results which related to small scales, impropriate study designs, enrollment criteria of infertility cause and titer/hormone concentration measurements. Furthermore, many questions remain unsettled in ART management in AITD infertile women attempt pregnancy. Therefore, further observational and interventional trials are needed more comprehensive multiple-center, double blinded, and randomized.

Maternal mild thyroid dysfunction and offspring cognitive and motor development from infancy to childhood: the Rhea mother-child cohort study in Crete, Greece

BACKGROUND

Maternal thyroid hormones' supply is crucial for fetal neurodevelopment; however, the role of maternal mild thyroid dysfunction is not clear. We aimed to assess the association of maternal mild thyroid dysfunction with child neuropsychological development from infancy to early childhood.

METHODS

We included 757 mother-child pairs from the prospective 'Rhea' cohort on Crete, Greece. Maternal thyroid functioning was assessed by quantitative analysis of serum thyroid-stimulating hormone, free thyroxine, thyroid peroxidase antibodies and thyroglobulin antibodies at early gestation (mean=14 weeks). Neuropsychological assessment was based on Bayley Scales of Infant Development (18 months of age), McCarthy Scales of Children's Abilities (4 years of age), Raven's Coloured Progressive Matrices, Trail Making Test and Finger Tapping Test (6 years of age).

RESULTS

In multivariate adjusted linear regression analyses, maternal hypothyroxinemia was associated with decreased verbal scores at 4 years and reduced motor speed at 6 years of age. Maternal thyroid autoimmunity was associated with decreased child perceptual and motor ability at 4 years of age. Four trajectories of longitudinal non-verbal cognitive development were identified and children exposed to maternal thyroid autoimmunity had increased risk for belonging to an adverse trajectory ('low': adjusted relative risk ratio (RRR) = 2.7 95% CI: (1.4, 5.2), 'high-decreasing': adjusted RRR = 2.2 95% CI: (1.2, 4.0), 'low-increasing': adjusted RRR = 1.8 95% CI: (1.0, 3.2)).

CONCLUSION

Maternal hypothyroxinemia is associated with reduced offspring verbal and motor ability. Maternal thyroid autoimmunity is associated with decreased offspring perceptual performance and motor ability and increased risk for adverse non-verbal cognitive development from infancy to childhood.

Universal screening for thyroid disease during pregnancy should be performed

Thyroid disease can significantly impact the pregnant woman and her child. Human and animal studies have firmly linked overt hypothyroidism and overt hyperthyroidism to miscarriage, preterm delivery and other adverse pregnancy outcomes. Overt hypothyroidism and overt hyperthyroidism affect 1% of all pregnancies. Treatment is widely available, and if detected early, results in decreased rates of adverse outcomes. Universal screening for thyroid disease in pregnancy can identify patients with thyroid disease requiring treatment, and ultimately decrease rates of complications. Universal screening is cost-effective compared to the currently accepted practice of targeted screening and may even be cost-saving in some healthcare systems. Targeted screening, which is recommended by most professional associations, fails to detect a large proportion of pregnant women with thyroid disease. In fact, an increasing number of providers are performing universal screening for thyroid disease in pregnancy, contrary to society guidelines. Limited evidence concerning the impact of untreated and treated subclinical disease and thyroid autoimmunity has distracted from the core rationale for universal screening - the beneficial impact of detecting and treating overt thyroid disease. Evidence supporting universal screening for overt disease stands independently from that of subclinical and autoimmune disease. The time to initiate universal screening is now.

TPO antibody positivity and adverse pregnancy outcomes

Thyroid autoimmunity (TAI) is prevalent amongst women of reproductive age. TAI describes the presence of circulating anti-thyroid autoantibodies that are targeted against the thyroid, with or without thyroid dysfunction. Thyroid peroxidase antibodies (TPOAb) are the most common anti-thyroid autoantibodies. Around 10% of biochemically euthyroid individuals also have an elevated TPOAb titre. Many studies have linked the presence of TPOAb to adverse maternal and fetal outcomes in pregnancy, in particular miscarriage and pre-term birth, even in the absence of thyroid dysfunction. The causal pathway is poorly understood and few trials have looked to find treatments to reduce adverse outcomes. This review discusses in detail the associated adverse outcomes of TPOAb in pregnancy and the results of trials exploring methods to reduce such outcomes. Recommendations for counselling and monitoring of women with TPOAb and suggested areas for future work are also outlined.

Impact of Thyroid Autoimmunity on Ovarian Reserve, Pregnancy Outcomes, and Offspring Health in Euthyroid Women Following In Vitro Fertilization/Intracytoplasmic Sperm Injection

Background: Thyroid autoimmunity (TAI) is the most frequent autoimmune disease among reproductive-aged women. It has been related to premature ovarian insufficiency, but the mechanisms remain elusive, and its association with ovarian reserve in euthyroid women is debatable. Moreover, the impact of TAI on assisted reproduction is controversial: especially for women with diminished ovarian reserve (DOR), few studies are available. Therefore, the present study was aimed to look for an association between TAI and DOR, and to evaluate the effect of TAI on pregnancy outcomes and offspring health following assisted reproductive technology stratified by ovarian reserve. Methods: A total of 6213 euthyroid women from the Reproductive Hospital Affiliated to Shandong University between 2012 and 2017 were retrospectively included. The prevalence of DOR in women with negative or positive TAI was calculated, and pregnancy and neonatal outcomes after in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycles were compared between the TAI-positive and TAI-negative groups both in women with DOR and in those with normal ovarian reserve (NOR). Longitudinal growth parameters and temperament type of the offspring were also observed in the TAI-positive and TAI-negative groups. Results: The prevalence of DOR in women with positive TAI and those with negative TAI was not significantly different (4.09% vs. 2.96%, p = 0.053), even after stratifying patients by age. In women with DOR, the live birth rate, pregnancy loss rate, neonatal complication rate, and offspring outcomes between the TAI-positive and TAI-negative groups were comparable (p > 0.05). In women with NOR, a higher rate of live births (44.94% vs. 40.34%, p = 0.027) and a higher prevalence of congenital anomalies (4.68% vs. 2.14%, p = 0.005) were observed in the TAI-positive group. Conclusions: TAI had no impact on ovarian reserve in euthyroid women and had no association with IVF/ICSI outcomes in women with DOR. Although an increased incidence of congenital anomalies in the TAI-positive group was observed in women with NOR, an association between neonatal anomalies and TAI cannot be demonstrated. Large cohort studies to evaluate the effects of TAI on offspring health are warranted, and further experimental studies are required to explore the underlying mechanisms.

Maternal thyroid disease and its effects on the fetus and perinatal outcomes

Thyroid disease is common in women of childbearing age and can have significant effects on the development of the fetus and perinatal outcomes. Maternal thyroid hormone is critical for proper fetal neurodevelopment, and the fetus relies on thyroid hormone from its mother for the first half of pregnancy. Both overt maternal hypothyroidism and overt maternal hyperthyroidism have been shown to be associated with adverse effects on central nervous system gray matter and neurocognitive development of offspring as well as increased obstetrical risks. Treatment of overt thyroid conditions improves outcomes. Subclinical maternal hypothyroidism may increase adverse neurocognitive and obstetrical outcomes although data are conflicting. To date, treatment of subclinical hypothyroidism has not shown benefit. Subclinical hyperthyroidism is well tolerated in pregnancy. Thyroid autoantibodies alone may also affect neurodevelopment and obstetrical outcomes; however, recent data have shown no improvement with levothyroxine treatment. Several rare maternal genetic thyroid conditions can affect the fetus including a thyroid-stimulating hormone receptor mutation leading to hypersensitivity to human chorionic gonadotropin and thyroid hormone resistance. The thyroid plays a crucial role in fetal health and understanding it is important for optimal care.

Hypothyroidism in Pregnancy

Hypothyroidism in pregnancy is defined as the presence of an elevated thyroid stimulating hormone during gestation, affecting 2% to 3% of the population. Overt hypothyroidism is diagnosed by a decreased FT4, while patients with a normal FT4 are considered to have subclinical disease. Poorly controlled disease is associated with both pregnancy complications and developmental delays in the offspring. Treatment consists of replacement with levothyroxine and regular monitoring. Most pregnant women will require an increase in their dosing from 25% to 30%. While treatment for SCH remains controversial, current recommendations do not support universal screening of low-risk women during pregnancy.

Inconsistencies in the management of neonates born to mothers with "thyroid diseases"

Although thyroid medications are frequently prescribed during pregnancy, paediatricians treating the respective neonates often have no information about the underlying maternal thyroid disease, and inconsistencies in postnatal diagnostics may result. We analysed a cohort of 1819 mothers admitted for delivery in 1 year to one hospital. We analysed the pre- and postpartum diagnostics in the mothers, the postnatal diagnostics in the neonates and their postnatal auxological development. Two hundred thirteen mothers (11.7%) had "thyroid disease"; 37 (2.0%) had Hashimoto thyroiditis, seven (0.4%) Graves' disease and 169 (9.3%) "thyroid disease of other origins". One hundred eighty-eight out of 213 (88%, 10.3% of the entire cohort) took levothyroxine. Pre- and postpartum diagnostics of the mothers and postnatal diagnostics of the neonates revealed striking inconsistencies. For example, 39 % of the gynaecologists routinely determined TSH, while only 59% carried out a dosage adjustment for known hypothyroidism. Second specialists were consulted in 86%. Unnecessary postpartum diagnostics were initiated in 19/213 neonates (9%). TRAb was analysed, however, in only one neonate born from the mothers with Graves' disease-a condition in which further diagnostic efforts are mandatory.Conclusion: Although many pregnant women have thyroid dysfunction, we observed a lack of uniformity in the diagnostic approach of the women and their neonates. What is Known: • Disturbed maternal thyroid function in pregnancy often has an adverse impact on both the mother and the foetus. • Although detailed guidelines for managing impaired maternal thyroid function during pregnancy have been published, their application in clinical practice varies widely. What is New: • Recommendations for managing the newborn of a mother presenting with thyroid disease of unknown entity are remarkably inconsistent. • This leads to a possible over-diagnosis in general and a potentially life-threatening failure to note neonatal hyperthyroidism requiring rapid treatment.

The Association of Maternal Thyroid Autoimmunity During Pregnancy With Child IQ

CONTEXT

Thyroperoxidase antibody (TPOAb) positivity is a major risk factor for gestational thyroid dysfunction. During the first 18 to 20 weeks of pregnancy, high concentrations of human chorionic gonadotropin (hCG) stimulate the thyroid to ensure adequate thyroid hormone availability for the developing fetus. However, TPOAb-positive women have an impaired thyroidal response to hCG stimulation.

OBJECTIVE

To study the association of maternal TPOAb positivity during pregnancy with child IQ.

DESIGN, SETTING, AND PARTICIPANTS

This study was embedded in two prospective birth cohorts: Generation R (Rotterdam, the Netherlands) and Avon Longitudinal Study of Parents and Children (ALSPAC; United Kingdom). Mother-child pairs with available data on early pregnancy TPOAb (≤18 weeks of gestation) and offspring IQ were included (n = 3637 for Generation R and n = 2396 for ALSPAC).

MAIN OUTCOME MEASURES

Child IQ at 5 to 10 years of age.

RESULTS

In Generation R, TPOAb positivity was associated with a 2.0 ± 0.9-point lower mean child IQ (P = 0.03). Sensitivity analyses showed negative effect estimates already from TPOAb concentrations considerably lower than currently used manufacturer cutoffs. In ALSPAC, neither TPOAb positivity nor TPOAb concentrations below manufacturer cutoffs were associated with child IQ (TPOAb positivity: 0.7 ± 1.0; P = 0.45). Adjustment for maternal TSH or free T4 concentrations or urinary iodine/creatinine ratio did not change the results.

CONCLUSION

TPOAb positivity during pregnancy was associated with lower child IQ in Generation R but not in ALSPAC. Further studies are needed to elucidate whether differences between the study populations, such as maternal iodine status, could be the underlying cause for these differences.

[Recommendations for the diagnosis and follow up of the foetus and newborn child born to mothers with autoimmune thyroid disease]

The objective of this document is to review the current recommendations in the management of the foetus and the newborn child born to mothers with autoimmune thyroid disease. In 2017, the American Thyroid Association published guidelines for the diagnosis and management of thyroid disease during pregnancy and post-partum. In this guide, 97 recommendations were made, and an algorithm for the diagnosis and treatment of gestational hypothyroidism was proposed. Also, in this last year, a wide review was been published on the foetal and neonatal approach of the child of a mother with Graves' disease. The importance of the determination of maternal antibodies against thyrotropin receptor in the second half of pregnancy is stressed, in order to adequately stratify the risk in the neonate.

Autoimmune thyroid disease during pregnancy

Understanding of changes in thyroid function and the consequences of thyroid disease during pregnancy has rapidly grown in the past two decades, and revised American Thyroid Association guidelines on this topic were published in 2017. This Review explores the association between thyroid autoimmunity and complications during and after pregnancy. Thyroid autoimmunity refers to the presence of antibodies to thyroperoxidase or thyroglobulin, or thyroid-stimulating hormone receptor antibodies (TRAbs), or a combination of these, and is present in up to 18% of pregnant women. Thyroid antibodies in pregnant women with normal functioning thyroids (ie, euthyroid) have been associated with several complications, including miscarriage and premature delivery. Treatments to improve pregnancy outcomes are being studied. Whether thyroid antibodies are associated with infertility and assisted reproductive technology outcomes is unclear; although, treatment with low doses of levothyroxine, which is usually used to treat hypothyroidism, can be considered in such situations. Additionally, thyroid antibodies have been associated with other neonatal and maternal complications. All these associations require confirmation in larger prospective studies, and their pathogenic mechanisms need to be better understood. Post-partum thyroiditis is substantially more frequent in women who have thyroid antibodies during pregnancy than in those who do not have thyroid antibodies; however, whether treatment can prevent post-partum thyroiditis in women who are or have been antibody positive is unknown. Finally, TRAbs cross the placenta from the mother to the fetus and can cause fetal or neonatal hyperthyroidism. Therefore, women who are positive for TRAbs during pregnancy should be monitored.

2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum

BACKGROUND

Thyroid disease in pregnancy is a common clinical problem. Since the guidelines for the management of these disorders by the American Thyroid Association (ATA) were first published in 2011, significant clinical and scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid disease in women during pregnancy, preconception, and the postpartum period.

METHODS

The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations. The guideline task force had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members.

RESULTS

The revised guidelines for the management of thyroid disease in pregnancy include recommendations regarding the interpretation of thyroid function tests in pregnancy, iodine nutrition, thyroid autoantibodies and pregnancy complications, thyroid considerations in infertile women, hypothyroidism in pregnancy, thyrotoxicosis in pregnancy, thyroid nodules and cancer in pregnant women, fetal and neonatal considerations, thyroid disease and lactation, screening for thyroid dysfunction in pregnancy, and directions for future research.

CONCLUSIONS

We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid disease in pregnant and postpartum women. While all care must be individualized, such recommendations provide, in our opinion, optimal care paradigms for patients with these disorders.

Thyroid in pregnancy: From physiology to screening

Thyroid hormones are crucial for the growth and maturation of many target tissues, especially the brain and skeleton. During critical periods in the first trimester of pregnancy, maternal thyroxine is essential for fetal development as it supplies thyroid hormone-dependent tissues. The ontogeny of mature thyroid function involves organogenesis, and maturation of the hypothalamus, pituitary and the thyroid gland; and it is almost complete by the 12th-14th gestational week. In case of maternal hypothyroidism, substitution with levothyroxine must be started in early pregnancy. After the 14th gestational week, fetal brain development may already be irreversibly affected by lack of thyroid hormones. The prevalence of manifest hypothyroidism in pregnancy is about 0.3-0.5%. The prevalence of subclinical hypothyroidism varies between 4 and 17%, strongly depending on the definition of the upper TSH cutoff limit. Hyperthyroidism occurs in 0.1-1% of all pregnancies. Positivity for antibodies against thyroid peroxidase (TPOAb) is common in women of childbearing age with an incidence rate of 5.1-12.4%. TPOAb-positivity may be regarded as a manifestation of a general autoimmune state which may alter the fertilization and implantation processes or cause early missed abortions. Women positive for TPOAb are at a significant risk of developing hypothyroidism during pregnancy and postpartum. Laboratory diagnosis of thyroid dysfunction during pregnancy is based upon serum TSH concentration. TSH in pregnancy is physiologically lower than the non-pregnant population. Results of multiple international studies point toward creation of trimester-specific reference intervals for TSH in pregnancy. Screening for hypothyroidism in pregnancy is controversial and its implementation varies from country to country. Currently, the case-finding approach of screening high-risk women is preferred in most countries to universal screening. However, numerous studies have shown that one-third to one-half of women with thyroid disorders escape the case-finding approach. Moreover, the universal screening has been shown to be more cost-effective. Screening for thyroid disorders in pregnancy should include assessment of both TSH and TPOAb, regardless of the screening approach. This review summarizes the current knowledge on physiology of thyroid hormones in pregnancy, causes of maternal thyroid dysfunction and its effects on pregnancy course and fetal development. We discuss the question of case-finding versus universal screening strategies and we display an overview of the analytical methods and their reference intervals in the assessment of thyroid function and thyroid autoimmunity in pregnancy. Finally, we present our results supporting the implementation of universal screening.