Thyroid autoantibodies and associated complications during pregnancy

Prediction of preterm delivery based on thyroid peroxidase antibody levels and other identified risk factors

OBJECTIVE

Thyroid dysfunction and TPOAb positivity during pregnancy are associated with adverse pregnancy outcomes such as preterm delivery. The aim of this study was to predict preterm delivery based on identified risk factors, especially TPOAb levels.

STUDY DESIGN

A secondary analysis was run on data collected in the Tehran Thyroid and Pregnancy study (TTPs). We used the data of 1515 pregnant women with singletons. The association between risk factors and preterm birth (delivery before 37 completed weeks of gestation) was investigated in univariate analysis. Multivariate logistic regression analysis was performed to identify independent risk factors, and a stepwise backward elimination method was used to determine the helpful combination of risk factors. The nomogram was developed based on a multivariate logistic regression model. The performance of the nomogram was evaluated using a concordance index and calibration plots with bootstrap samples. Statistical analysis was performed using STATA software package; the significance level was set at P < 0.05.

RESULTS

Based on multivariate logistic regression analysis, a combination of previous preterm delivery [OR: 5.25; 95 %CI: (2.13-12.90), p < 0.01], TPOAb [OR: 1.01; 95 %CI: (1.01-1.02), and T4 [OR: 0.90; 95 %CI: (0.83-0.97); p = 0.04] as independent risk factors that most precisely predicted preterm birth. The area under the curve (AUC) was 0.66 (95% CI: 0.61-0.72). The calibration plot suggests that the fit of the nomogram is reasonable.

CONCLUSION

A combination of T4, TPOAb, and previous preterm delivery was identified as independent risk factors that accurately predicted preterm delivery. The total score obtained based on the nomogram designed based on risk factors can predict the risk of preterm delivery.

The role of immune cells and mediators in preeclampsia

Preeclampsia is a hypertensive disorder of major concern in pregnancy than can lead to intrauterine growth restriction, placental abruption and stillbirth. The pathophysiology of preeclampsia is multifactorial, including not only kidney dysfunction but also endothelial dysfunction, as the maternal endothelium becomes exposed to placental factors that are released into the circulation and increase systemic levels of vasoconstrictors, oxidative stress, anti-angiogenic factors and inflammatory mediators. Importantly, inflammation can lead to insufficient placental perfusion and low birthweight in offspring. Various innate and adaptive immune cells and mediators have been implicated in the development of preeclampsia, in which oxidative stress is associated with activation of the maternal inflammatory response. Immune cells such as regulatory T cells, macrophages, natural killer cells, and neutrophils are known to have major causative roles in the pathology of preeclampsia, but the contributions of additional immune cells such as B cells, inflammatory cytokines and anti-angiotensin II type 1 receptor autoantibodies are also now recognized. Immunological interventions, therefore, have therapeutic potential in this disease. Here, we provide an overview of the immune responses that are involved in the pathogenesis of preeclampsia, including the role of innate and adaptive immune cells and mediators.

The Role of B Cells in PE Pathophysiology: A Potential Target for Perinatal Cell-Based Therapy?

The pathophysiology of preeclampsia (PE) is poorly understood; however, there is a large body of evidence that suggests a role of immune cells in the development of PE. Amongst these, B cells are a dominant element in the pathogenesis of PE, and they have been shown to play an important role in various immune-mediated diseases, both as pro-inflammatory and regulatory cells. Perinatal cells are defined as cells from birth-associated tissues isolated from term placentas and fetal annexes and more specifically from the amniotic membrane, chorionic membrane, chorionic villi, umbilical cord (including Wharton's jelly), the basal plate, and the amniotic fluid. They have drawn particular attention in recent years due to their ability to modulate several aspects of immunity, making them promising candidates for the prevention and treatment of various immune-mediated diseases. In this review we describe main findings regarding the multifaceted in vitro and in vivo immunomodulatory properties of perinatal cells, with a focus on B lymphocytes. Indeed, we discuss evidence on the ability of perinatal cells to inhibit B cell proliferation, impair B cell differentiation, and promote regulatory B cell formation. Therefore, the findings discussed herein unveil the possibility to modulate B cell activation and function by exploiting perinatal immunomodulatory properties, thus possibly representing a novel therapeutic strategy in PE.

Association of thyroid antibodies status on the outcomes of pregnant women with hypothyroidism (maternal hypothyroidism on pregnancy outcomes, MHPO-4)

Background

Autoimmunity increases with age and is often commonly evaluated in women of the reproductive age group. Prevalence of thyroid antibodies is common even in euthyroid pregnant women. We aim to compare the association of thyroid antibody status on the maternal and neonatal outcomes in pregnant women with hypothyroidism.

Methods

We conducted a cross-sectional retrospective study on 718 cases in the Aga Khan University Hospital. Information was collected on pregnant women who have been diagnosed with hypothyroidism before conception or during their antenatal period. Laboratory data were recorded for thyroid peroxidase antibodies, anti-thyroglobulin antibodies, and thyroid-stimulating hormone levels. Maternal and neonatal outcomes were also noted from medical file records. Data analysis was performed on Statistical Package for the Social Sciences version 20.0.

Results

Overall, 146 out 718 cases were included for final analysis. Thyroid peroxidase antibodies were positive in 66.4% and anti-thyroglobulin was positive in 52.1% cases, whereas 43.8% of cases had both antibodies positive. Pre-gestational diabetes was significantly associated with thyroid autoimmunity. There was a 73% less chance of gestational hypertension for thyroid autoimmune groups. Gestational diabetes and maternal (chronic) hypertension were found to have an independent effect on postpartum hemorrhage. Hypertensive disorders in pregnancy were found to have an independent risk for premature birth.

Conclusion

Our study reports a 74.7% prevalence of positive thyroid antibodies in hypothyroid pregnant women, with higher association with pre-gestational diabetes. Gestational hypertension was least likely to occur in thyroid autoimmune groups. None of the outcomes were independently associated with worse outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03594-y.

Knowledge of Thyroid Disorders during Pregnancy among General Practitioners in Iran

BACKGROUND AND OBJECTIVES

Thyroid disorders during pregnancy are important health problems worldwide. The aim of this study was to assess the knowledge of general practitioners (GPs) about thyroid disorders during pregnancy.

METHODS

In this cross sectional study, 120 GPs were randomly selected among participants of a continuous medical education (CME) program, entitled "practical endocrinology". To assess the knowledge and educational requirements of GPs regarding thyroid disorders during pregnancy, a validated and localized multiple-choice questionnaire was used.

RESULTS

A total of 100 GPs completed the questionnaire. The mean age of the participants was 37.0 years, and 41.4% were men. The mean knowledge score of GPs was 39.9%. On average, the rate of correct response to questions concerning the definition, pathophysiology, diagnosis, complications, and treatment of thyroid disorders was 39.0%, 39.3%, 48.8%, 34.3%, and 44.6%, respectively. There was a significant difference in knowledge among GPs, who had and had not passed the training course on thyroid disorders. In addition, GPs who had passed continuous medical education programs obtained higher knowledge scores regarding diagnosis and treatment (P < 0.05).

CONCLUSIONS

GPs attending pregnant women in Iran lack sufficient information on the pathophysiology, diagnosis, and management of thyroid disorders during pregnancy. Considering the key role of GPs in the public healthcare system, design of high-quality educational programs and development of specific educational packages about thyroid disorders and pregnancy are necessary.

Beneficial Effects on Pregnancy Outcomes of Thyroid Hormone Replacement for Subclinical Hypothyroidism

Background. Hypothyroidism and raised thyroid antibody levels have been associated with adverse obstetrical outcomes. Several studies have investigated causal associations, but results have been inconsistent and few studies have reported the effects of thyroxine replacement therapy on pregnancy outcomes in hypothyroid patients. Objective. The primary study objective was to determine the outcome of pregnancies in women diagnosed with overt and subclinical hypothyroidism (SCH) (serum TSH > 2.5 mIU/L) and those with elevated circulating thyroid autoantibody levels in the first trimester of pregnancy and after the institution of appropriate thyroxine replacement therapy to maintain the serum TSH ≤ 2.5 mIU/L. Study Design. This prospective observational study was undertaken between 2013 and 2016. Blood samples were taken from 1025 women at presentation for thyroid stimulating hormone (TSH), anti-thyroglobulin antibodies (TGAb), and thyroid peroxidase antibodies (TPOAb). Those with a TSH > 2.5 mIU/L were treated with thyroxine and managed appropriately to ensure that the TSH was maintained ≤2.5 mIU/L. Outcomes in these patients were compared to those in euthyroid patients. Maternal antenatal complications and perinatal outcomes were recorded. Results. There were a total of 1025 patients of whom 382 (37.5%) were nulliparous. 10.1% had a TSH level > 2.5 mIU/L and 18.2% had at least one raised thyroid antibody level. No differences in adverse outcomes of pregnancy were evident in women treated for SCH or overt hypothyroidism compared to the euthyroid group. There was also no association between raised thyroid antibodies and adverse pregnancy outcomes in either group. Conclusion. There were no adverse outcomes of pregnancy found in pregnant women who had been diagnosed and treated with thyroxine for SCH at the time of presentation when compared to euthyroid patients. There was also no relationship with thyroid antibodies and adverse pregnancy outcomes in the two groups. It is not possible to unequivocally advocate for thyroxine replacement in pregnant women with subclinical and overt hypothyroidism until large scale randomized controlled trials are performed.

Anti-TPO antibodies diffusion through the placental barrier during pregnancy

BACKGROUND

Hashimoto's thyroiditis is the principal aetiology of hypothyroidism with presence of anti-thyroperoxidase antibodies (anti-TPO). The association between anti-TPO and foeto-placental complications has been observed in previous studies. To go further in the understanding, the current study compares the level of anti-TPO in maternal blood and in the cord blood of her fetus at the moment of childbirth to demonstrate the passage of anti-TPO through the placenta barrier.

METHODS AND FINDINGS

This study was realised in a maternity ward located in the Northern district of Paris, France from 2006 to 2007. Women with normal pregnancy were included in a first study and only women with no abnormal thyroid dosage at baseline and tested positive with anti-TPO were prospectively enrolled. Maternal blood samples were collected in the third trimester and at the arrival to the ward when patients came to deliver. After delivery, cord blood sample was collected. Pearson's correlation coefficient was computed. 5941 patients delivered in the ward during the study, 33 pregnant women were included. We found a correlation between the anti-TPO levels in maternal and in the cord blood of their fetus with a correlation coefficient of 0.98 and a p-value<0.001.

CONCLUSIONS

This is the first demonstration of the free passage through the placental barrier of anti-TPO from the mother to the fetus at the moment of childbirth. These findings can be extrapolated all along pregnancy and open the door to a direct action of the anti-TPO on fetus and to a possible action on the fetal thyroid.

Establishing trimester-specific maternal thyroid function reference intervals

Background

Thyroid disorders are common in women of childbearing age and are associated with adverse pregnancy outcomes. Physiological changes in pregnancy and the lack of pregnancy-specific reference ranges make managing thyroid disorders in pregnancy challenging. Our aim was to establish trimester-specific thyroid function reference intervals throughout pregnancy, and to examine the prevalence of thyroid autoimmunity in otherwise euthyroid women.

Method

This was a prospective, cross-sectional study of thyroid function tests (TFTs) in pregnant women attending a large, tertiary referral maternity hospital. Patients with known thyroid disorders, autoimmune disease, recurrent miscarriage, hyperemesis gravidarum and pre-eclampsia were excluded. TFTs were analysed in the CUH biochemistry laboratory using Roche Modular E170 electrochemiluminescent immunoassay. Trimester-specific reference ranges (2.5th, 50th and 97.5th centiles) were calculated.

Results

Three-hundred-and-fifty-one women were included into the analysis. Median maternal age was 30. Thyroid-stimulating hormone concentrations showed slightly increasing median centile throughout gestation. Free thyroxine (T4) and T3 decreased throughout gestation. Table 1 demonstrates the calculated percentiles according to gestational weeks.

Conclusion

We established pregnancy-specific thyroid function reference intervals for our pregnant population, for use in clinical practice.

CD19 + CD5 + Cells as Indicators of Preeclampsia

Preeclampsia is a devastating pregnancy-associated disorder affecting 5% to 8% of pregnant women worldwide. It emerges as an autoimmune-driven disease, and, among others, the autoantibodies against angiotensin type 1 receptor II have been proposed to account for preeclampsia symptoms. Despite much attention focused on describing autoantibodies associated with preeclampsia, there is no clue concerning the cell population producing them. CD19 + CD5 + B-1a B cells constitute the main source of natural and polyreactive antibodies, which can be directed against own structures. Here, we aimed to identify the B-cell subpopulation responsible for autoantibody production during preeclampsia and to study their regulation, as well as their possible use as markers for the disease. The frequency of CD19 + CD5 + cells in peripheral blood of preeclamptic patients is dramatically increased compared with normal pregnant women as analyzed by flow cytometry. This seems to be driven by the high human chorionic gonadotropin levels present in the serum and placenta supernatant of preeclamptic patients versus normal pregnant women. Not only ≈95% of CD19 + CD5 + cells express the human chorionic gonadotropin receptor, but these cells also expand on human chorionic gonadotropin stimulation in a lymphocyte culture. Most importantly, isolated CD19 + CD5 + cells produce autoantibodies against angiotensin type 1 receptor II, and CD19 + CD5 + cells were further detected in the placenta of preeclamptic but not of normal pregnancies where barely B cells are present. Our results identify a B-cell population able to produce pregnancy-pathological autoantibodies as possible markers for preeclampsia, which opens vast diagnostic and therapeutic applications.