The Clinical Value and Variation of Antithyroid Antibodies during Pregnancy

An analysis of real-life data of infants born to mothers with autoimmune thyroiditis: do they need to be followed-up?

BACKGROUND

Infants born to mothers with autoimmune thyroiditis (AT) could be at risk of developing thyroid dysfunction, and maternal anti-thyroid antibodies have been shown to have a clinical impact on offspring. We aimed at evaluating the usefulness of our follow-up intervention protocol in newborns from mothers with AT and to define the most appropriate management for these neonates.

METHODS

89 mothers with AT and their newborns were included. Data on maternal thyroid function and autoimmunity were collected; serum thyroid function and autoimmunity of infants were assessed regularly until normalisation of thyroid stimulating hormone (TSH) and anti-thyroid antibodies, according to the local protocol.

RESULTS

Thyroid auto-antibodies were measured in 38% and in 62% of mothers before and during pregnancy, respectively. Anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG) were positive in 97% and 61%, respectively, of the mothers assessed. Anti-TSH receptor antibodies (TRAb) were checked in 18% of the mothers and all were negative. 94% of newborns at first evaluation had positive anti-thyroid antibodies, starting to normalise or decrease from the second month of life. Analysing TSH levels according to the days of postnatal life of collection samples (T1: 30 ± 7 days, T2: 61 ± 9 days, T3: 105 ± 49 days, T4: 135 ± 31 days, T5: 247 ± 64 days), peak TSH levels were found at T4 (4.4 ± 2.2 mU/L), within the cut-off of 6 mU/L. 84% of children maintained a normal thyroid function during follow-up; 12% of infants presented a TSH above 6 mU/L at least in one blood test, showing normalisation during follow-up. Only one infant received replacement therapy for hypothyroidism at 2 months. 91% of the 22 thyroid ultrasounds (US) performed were normal. In those with changes thyroid function normalised anyway.

CONCLUSIONS

Mothers with AT do not seem to deliver newborns at risk of overt hypothyroidism. However, because of the possible negative effects of maternal anti-thyroid antibodies, we underline the importance of monitoring thyroid autoimmunity during pregnancy, including both anti-TG besides anti-TPO antibodies.

Autoimmune Thyroid Disease and Pregnancy: The Interaction Between Genetics, Epigenetics and Environmental Factors

Autoimmune thyroid disease (AITD) is the leading cause of thyroid dysfunction globally, characterized primarily by two distinct clinical manifestations: Hashimoto's thyroiditis (HT) and Graves' disease (GD). The prevalence of AITD is approximately twice as high in women compared to men, with a particularly pronounced risk during the reproductive years. Pregnancy exerts profound effects on thyroid physiology and immune regulation due to hormonal fluctuations and immune adaptations aimed at fostering maternal-fetal tolerance, potentially triggering or exacerbating AITD. The impact of AITD on pregnancy outcomes is multifaceted. Both HT and GD have been associated with adverse obstetric and neonatal outcomes, including miscarriage, preterm delivery, preeclampsia and fetal growth restriction. Inadequately managed AITD can also affect fetal neurodevelopment due to disrupted maternal thyroid hormone availability during critical periods of brain maturation. This review explores the complex interplay between the genetic, epigenetic and environmental factors that drive AITD during pregnancy, highlighting their roles in disease development and impacts on pregnancy outcomes. Gaining a deeper understanding of these mechanisms is crucial for improving diagnostic tools, treatment options and preventive measures to enhance the health and well-being of both the mother and the newborn.

Best practices in the laboratory diagnosis, prognostication, prediction, and monitoring of Graves' disease: role of TRAbs

Graves' disease (GD) is an autoimmune disorder characterized by activation of the TSH receptor by stimulatory autoantibodies (TSH Receptor Antibodies, or TRAbs), leading to unregulated thyroid hormone production. Diagnosis is largely based on the typical clinical picture and laboratory thyroid panel. Establishment of elevated serum levels of TRAbs by competitive binding assay or cell-binding assay has its unique role in diagnosis and management of GD, especially in the differential diagnosis, therapy selection, prognostication, evaluation of thyroid function during pregnancy, peri-conceptional and neonatal thyroid workup, and in certain special situation. Inclusion of TRAbs in GD diagnostic algorithm can improve cost-effectiveness of GD management. The current best practice guidelines were developed to provide evidence-based recommendations in the use of TRABs in GD management for healthcare providers in South Asia. A panel of endocrinologists with minimum 10 years of clinical experience in thyroid disorders reviewed existing literature and their quality, and after deliberation and discussion, developed 21 recommendations surrounding the best practices surrounding the role of TRAbs in GD management.

Effect of thyroid peroxidase antibody titers trajectories during pregnancy and postpartum on postpartum thyroid dysfunction

OBJECTIVE

To identify risk factors contributing to the development of postpartum hypothyroidism in women newly diagnosed with subclinical hypothyroidism (SCH) during the first trimester of pregnancy (T1). Additionally, this study aimed to explore the impact of thyroid peroxidase antibody (TPOAb) titers trajectories throughout pregnancy and postpartum.

METHODS

Thyroid hormone levels and thyroid autoantibody titers were collected from T1 to the 12th month postpartum. Logistic regression analysis was employed to identify independent risk factors for hypothyroidism at the 12th month postpartum and to develop a prediction model. Model performance was assessed through discrimination, calibration, and clinical applicability, with internal validation using the bootstrap resampling method. Growth Mixture Modeling was applied to delineate the trajectory of TPOAb titers during pregnancy and postpartum, and logistic regression analysis was conducted to investigate the influence of these trajectories on the occurrence of postpartum hypothyroidism.

RESULTS

At the 12th month postpartum, hypothyroidism was either newly diagnosed or persisted in 76 of 209 cases (36.36%). Several significant risk factors for postpartum hypothyroidism were identified, including multiparity, positive TPOAb in T1, positive TPOAb and thyroglobulin antibody in T1, serum thyroid-stimulating hormone levels at SCH diagnosis in T1, and the final dose of levothyroxine in the third trimester. A prediction model was constructed and presented with a nomogram. Furthermore, a higher trajectory of serum TPOAb titer during pregnancy and postpartum emerged as a predictive factor for hypothyroidism at the 12th month postpartum.

CONCLUSION

Women with elevated TPOAb titers during pregnancy and postpartum necessitate ongoing and vigilant monitoring of thyroid function, even after childbirth.

Innate Immunity in Autoimmune Thyroid Disease during Pregnancy

Autoimmune thyroid disease (AITD) is the most common organ-specific autoimmune disorder clinically presented as Hashimoto thyroiditis (HT) and Graves' disease (GD). The pathogenesis of AITD is caused by an inappropriate immune response related to genetic, non-genetic, and environmental factors. Pregnancy is one of the factors that have a great influence on the function of the thyroid gland because of the increased metabolic demand and the effects of hormones related to pregnancy. During pregnancy, an adaptation of the maternal immune system occurs, especially of the innate immune system engaged in maintaining adaptive immunity in the tolerant state, preventing the rejection of the fetus. Pregnancy-related hormonal changes (estrogen, progesterone, hCG) may modulate the activity of innate immune cells, potentially worsening the course of AITD during pregnancy. This especially applies to NK cells, which are associated with exacerbation of HD and GD. On the other hand, previous thyroid disorders can affect fertility and cause adverse outcomes of pregnancy, such as placental abruption, spontaneous abortion, and premature delivery. Additionally, it can cause fetal growth retardation and may contribute to impaired neuropsychological development of the fetus. Therefore, maintaining the thyroid equilibrium in women of reproductive age and in pregnant women is of the highest importance.

In infertile women with subclinical hypothyroidism, with or without thyroid peroxidase antibodies, serum TSH during pregnancy follows preconception values and thyroid hormones remain stable

STUDY QUESTION

How does subclinical hypothyroidism, defined in infertile women during preconception by thyroid-stimulating hormone (TSH) >2.5 or >4.5 mIU/l, with or without thyroid peroxidase antibodies (anti-TPO) >100 IU/ml, impact thyroid hormone levels during pregnancy and after birth?

SUMMARY ANSWER

During pregnancy, TSH levels remain similar to those in preconception, even with supplementary thyroxine, whereas the serum levels of anti-TPO progressively decline.

WHAT IS KNOWN ALREADY

Overt hypothyroidism impacts both pregnancy and offspring but randomized clinical trials and cohort studies failed to detect the benefit of treatment with thyroxine in cases with low-threshold TSH or with anti-TPO during pregnancy.

STUDY DESIGN SIZE DURATION

First, the prevalence and reproducibility of two candidate cut-off levels of subclinical hypothyroidism in a cohort of 177 infertile women was compared with 171 women not aiming for pregnancy. Second, the impact of distinct setpoints of TSH in preconception (with or without anti-TPO) was monitored during pregnancy in 87 previously infertile women by high-frequency monitoring of thyroid function. Both studies were carried out from 2007 to 2019.

PARTICIPANTS/MATERIALS SETTING METHODS

Reproducibility and prevalence of subclinical hypothyroidism were examined in infertile women presenting in the fertility care unit of an academic institution. Women not aiming for pregnancy participated as controls. In both groups, TSH and anti-TPO were measured two times on different occasions. In addition, a group of previously infertile women with known preconception setpoints of TSH (with or without anti-TPO) were followed up prospectively throughout pregnancy and after birth. During pregnancy, serum was sampled weekly until Week 12, then monthly until delivery, and once after birth. Only cases with preconception TSH >4.5 mIU/l were supplemented with thyroxine. After collection of all samples, the serum levels of anti-TPO and the major thyroid hormones were measured. Prolactin with known fluctuations during pregnancy was used as reference.

MAIN RESULTS AND THE ROLE OF CHANCE

Measures of both TSH and anti-TPO at two different time points were accurate and reproducible. The odds of subclinical hypothyroidism in infertile women and controls were similar. During pregnancy, TSH closely followed preconception TSH levels, whereas serum levels of the thyroid hormones predominantly remained within or above (not below) the reference. Treatment of infertile women with preconception TSH >4.5 mIU/l with thyroxine resulted in higher free thyroxine (fT4) serum levels. The serum levels of anti-TPO declined as pregnancies evolved.

LIMITATIONS REASONS FOR CAUTION

The numbers of participants both in the prevalence study and in pregnancy did not reach the a priori estimated numbers. For ethical reasons, the patients with preconception TSH >4.5 mIU/l were treated with thyroxine. The findings apply to infertile women only.

WIDER IMPLICATIONS OF THE FINDINGS

We propose to use >4.5 mIU/l as the serum TSH threshold for supplementing women with thyroxine before pregnancy. During pregnancy, fT4 may be the better marker to monitor thyroid function. The consistent decrease of anti-TPO antibody levels during ongoing pregnancies must be considered a protective element.

STUDY FUNDING/COMPETING INTERESTS

The prevalence part of this study was supported by Merck-Serono, Geneva (TH006/EMR200007-603). The hormone measurements of the serum samples collected during the follow-up pregnancies were made possible by financial support of Roche Diagnostica (November 1721, 2017, Rotkreuz, Switzerland). I.D.G. was supported by a grant of the Repronatal Foundation, Basel, Switzerland. All authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

Research Database of UniBasel, project no. 576691 (2007).

Association of maternal thyroid peroxidase antibody during pregnancy with placental morphology and inflammatory and oxidative stress responses

Background

Studies suggest that thyroid peroxidase antibody (TPOAb) positivity exposure during pregnancy may contribute to changes in placental morphology and pathophysiology. However, little is known about the association of maternal TPOAb during pregnancy with placental morphology and cytokines. This study focuses on the effect of repeated measurements of maternal TPOAb during pregnancy on the placental morphology and cytokines.

Methods

Based on Ma'anshan Birth Cohort (MABC) in China, maternal TPOAb levels were retrospectively detected in the first, second and third trimesters. Placental tissues were collected 30 minutes after childbirth, placental morphological indicators were obtained by immediate measurement and formula calculation, and cytokine mRNA expression was detected by real-time quantitative polymerase chain reaction (RT-qPCR) afterward. Generalized linear models and linear mixed models were analyzed for the relationships of maternal TPOAb in the first, second and third trimesters with placental indicators.

Results

Totally 2274 maternal-fetal pairs were included in the analysis of maternal TPOAb levels and placental morphology, and 2122 pairs were included in that of maternal TPOAb levels and placental cytokines. Maternal TPOAb levels in early pregnancy were negatively associated with placental length, thickness, volume, weight and disc eccentricity, while positively correlated with placental IL-6, TNF-α, CRP, CD68, MCP-1, IL-10, HO-1, HIF-1α and GRP78. In mid-pregnancy, maternal TPOAb levels were negatively correlated with placental length, width and area. In late pregnancy, maternal TPOAb levels were negatively correlated with placental length, area, volume and weight. Repeated measures analysis showed that maternal TPOAb positivity tended to increase placental TNF-α, CD68 and MCP-1 while decreasing placental length, width and area than TPOAb negativity. Repeated measures analysis showed that maternal TPOAb levels were positively correlated with placental IL-6, TNF-α, CD68, MCP-1, IL-10, HO-1, HIF-1α and GRP78, while negatively correlated with placental length, area, volume, weight, and disc eccentricity.

Conclusion

There may be trimester-specific associations between maternal TPOAb levels and placental morphology and inflammatory and oxidative stress responses. The effect of maternal TPOAb levels on placental morphology is present throughout pregnancy. Early pregnancy may be the critical period for the association between maternal TPOAb levels and placental inflammatory and oxidative stress responses.

Cut-offs for thyroid peroxidase and thyroglobulin antibodies in early pregnancy

Objective

Thyroid disease in women of reproductive age is mainly of autoimmune origin, and thyroid peroxidase antibodies (TPO-Ab) as well as thyroglobulin antibodies (Tg-Ab) are key markers. Adding to this, much focus in pregnancy is on euthyroid women who are thyroid antibody positive. Evidence to substantiate the cut-offs for the definition of thyroid autoantibody positivity in early pregnant women is warranted.

Methods

Stored serum samples from 14,030 Danish pregnant women were used for the measurement of TPO-Ab, Tg-Ab, TSH, and free thyroxine (ADVIA Centaur XPT, Siemens Healthineers). Among all women, a reference cohort of 10,905 individuals was identified for the establishment of antibody cut-offs. Percentile cut-offs for TPO-Ab and Tg-Ab were determined using regression on order statistics (the reference cohort). The established cut-offs were then applied (the full cohort), and frequencies of early pregnancy as well as later diagnosis of hypothyroidism were evaluated.

Results

The highest established cut-offs (95th, 97.5th, and 99th percentiles) were 59, 68, and 81 U/mL for TPO-Ab and 33, 41, and 52 U/mL for Tg-Ab. When the cut-offs were applied in the full cohort, 11.0, 10.2, and 9.7% were TPO-Ab positive, whereas 13.3, 12.3, and 11.2% were Tg-Ab positive. Antibody-positive women (TPO-Ab and/or Tg-Ab) had higher median TSH and were more likely to have hypothyroidism in early pregnancy and to be diagnosed with hypothyroidism during follow-up.

Conclusions

This large study established and evaluated pregnancy-specific cut-offs for TPO-Ab and Tg-Ab. The findings are important regarding the classification of exposure in pregnancy and assessment of thyroid autoimmunity per se.

Impact of anti-thyroid peroxidase and anti-thyroglobulin antibodies on the gestational outcome of euthyroid pregnancies: A retrospective study

BACKGROUND

Thyroglobulin (anti-TG) and/or thyroid peroxidase (anti-TPO) autoantibodies are associated with higher rates of poor gestational outcomes.

OBJECTIVE

To demonstrate the impact of anti-TPO and anti-TG autoantibodies on the gestational outcomes of euthyroid pregnant women with a history of poor gestational outcome and thyroid gland disorders.

METHODS

This retrospective study included totally 75 euthyroid pregnant, 30 of women with high thyroid autoantibodies (Anti-TPO/Thyroglobulin-positive group) and 45 of them without autoantibodies (control group).

RESULTS

We could not demonstrate significant differences between two groups in terms of risk factors/co-morbidities, obstetric complications, gestational outcomes, and birth data (p> 0.05). However, enhanced miscarriage rates were observed among the Anti-TPO/Thyroglobulin-positive and control groups without significance (36.7% and 17.8% respectively, p= 0.116). High neonatal intensive care unit (NICU) admission rates were found for control and Anti-TPO/Thyroglobulin-positive groups (16.2% and 21.1%, respectively) (p= 0.720). Clinically, we compared the two groups in terms of the existence and the types of goiter (diffuse and nodular), and demonstrated that nodular goiter was statistically more frequent in the control group (40.0% vs. 8.7%, p= 0.015). Alongside, relatively high hereditary thrombophilia and type-2 diabetes mellitus rates were found in the Anti-TPO/Thyroglobulin-positive group (20.0% and 20.0%).

CONCLUSION

Thyroid autoantibody positivity is likely a risk factor for early pregnancy loss and NICU admission.

Glucocorticoids Improve the Pregnancy Rate and Outcome in Women With Unexplained Positive Autoantibodies: A Systematic Review and Meta-Analysis

The effect of glucocorticoid therapy on women with unexplained positive autoantibodies is under debate. This systemic review and meta-analysis were performed to evaluate whether glucocorticoid administration can improve the pregnancy outcome of this population. Relevant publications were searched from databases, and a total of seven prospective and retrospective cohort studies that investigated the effects of glucocorticoid administration on women with unexplained positive autoantibodies, were included. The outcomes of our systematic review and meta-analysis were measured in terms of risk ratios (RR) with 95% confidence intervals (CI) using fixed or random effect models. We found that glucocorticoid treatment improved the clinical pregnancy rate (RR 2.19, 95% CI 1.64–2.92) and live birth rate (RR 1.92, 95% CI 1.17–3.16), especially when glucocorticoid administration was started before pregnancy (clinical pregnancy rate: RR 2.30, 95% CI 1.58–3.34; live birth rate: RR 2.30, 95% CI 1.58–3.34). However, no effect of glucocorticoids on the miscarriage rate was found (RR 0.75, 95% CI 0.55–1.02) regardless of the time of drug administration. Our systematic review and meta-analysis support the rational use of glucocorticoids in women with unexplained positive autoantibodies.

Neonatal Outcomes of Pregnancies Complicated by Maternal Hyperthyroidism

Objective

This study aimed to determine the proportion, clinical characteristics, hormonal status, median time for normalization of serum thyroxine (FT4) and thyroid-stimulating hormone (TSH) and factors affecting time to thyroid function test (TFT) normalization of neonates born to mothers with maternal hyperthyroidism admitted in our institution.

Methodology

This was a retrospective cohort study that included 170 newborns admitted to the Neonatal Intensive Care Unit (NICU) of Hospital Universiti Sains Malaysia (HUSM) with a history of maternal hyperthyroidism from January 2013 until December 2018. We analyzed their baseline demographic and clinical characteristics, maternal thyroid status and antibody levels. Finally, we analyzed newborn thyroid function and thyroid antibodies.

Results

The proportion of neonates born to mothers with maternal hyperthyroidism was 0.8% (170 of 20,198 neonates within the study period). Seven (4.1%) developed overt hyperthyroidism, while four (2.4%) had thyroid storm. The median time for thyroid function test normalization was 30 days (95% CI: 27.1 to 32.8). The median time for TFT normalization was longer among neonates of mothers with positive thyroid antibodies [46.6 days (95% CI, 20.6 to 39.4)] and of mothers who received anti-thyroid treatment [31.7 days (95% CI, 23.5 to 39.9)].

Conclusion

Neonates born to mothers with hyperthyroidism is uncommon. These babies were observed to have a longer time for normalization of thyroid function tests if their mothers had thyroid antibodies or received anti-thyroid treatment.