Screening for autoimmune thyroid disorders after spontaneous abortion is cost-saving and it improves the subsequent pregnancy rate

Subclinical hypothyroidism in the infertile female population: a guideline

There is controversy regarding whether to treat subtle abnormalities of thyroid function in infertile female patients. This guideline document reviews the risks and benefits of treating subclinical hypothyroidism in female patients with a history of infertility and miscarriage, as well as obstetric and neonatal outcomes in this population.

Health Economics and Equity in Preconception Health Care: A Systematic Review

Poor pregnancy outcomes affect a child's lifelong health and disadvantaged populations are at higher risk of poor pregnancy outcomes. Preconception care aims to improve pregnancy outcomes by managing conditions and risks prior to conception. Given known inequities in pregnancy outcomes, the adoption of preconception care may benefit disadvantaged populations. Health economics plays an important role in the implementation of interventions, as economic evaluations seek to identify the most efficient and equitable care options. This review aimed to identify the cost-effectiveness of preconception care and how equity has been considered in these evaluations. A systematic review of literature published between 2012-2022 was undertaken to identify studies that evaluate the economic outcomes of preconception care. Studies that met the inclusion criteria were manually searched for consideration of equity in the economic evaluation analysis. Costs were presented and a narrative synthesis of studies reporting on outcomes of equity was conducted. Eight studies met the inclusion criteria, and only two reported on aspects of equity, specifically ethnicity. Considering the significant disparities in pregnancy outcomes among disadvantaged populations, aspects of equity are important to consider when implementing and evaluating preconception interventions. Therefore, it is recommended that future research focuses on the cost-effectiveness of preconception care and that these evaluations incorporate aspects of equity.

Reproductive Outcomes in Cases of Subclinical Hypothyroidism and Thyroid Autoimmunity: A Narrative Review

Thyroid diseases are relatively common in women in the reproductive period. It is currently understood that clinically-evident thyroid disorders may impair ovulation and, consequently, fertility. However, to date it has not been proven that high serum levels of thyroid-stimulating hormone and/or positivity for antithyroid antibodies are associated to a reduction in fertility, mainly in the absence of altered thyroxine levels. The present comprehensive review aims to present current data on the association between subclinical hypothyroidism and/or thyroid autoimmunity and reproductive outcomes.

The role of levothyroxine in obstetric practice

Thyroid hormones play a pivotal role in somatic growth, metabolic regulation and neurodevelopment. There is growing evidence regarding adverse obstetric and perinatal consequences of maternal thyroid hypofunction during early stages of pregnancy. These include: early pregnancy loss, preterm delivery and lower intelligence quotient (IQ) in children. Different clinical guidelines have been published by scientific societies for the management of thyroid diseases during pregnancy and levothyroxine (LT₄) has become a therapeutic agent increasingly prescribed by obstetricians. The aim of this work was to search for both similarities and controversial clinical aspects from the currently available literature. Guidelines published from 2011 onwards have been analysed and compared, in order to clarify the evidence about the involvement of thyroid dysfunction in pregnancy complications and the impact of LT₄ use in their prevention and/or treatment. This review summarizes the most updated knowledge about the effectiveness of LT₄ for pregnancy complications, the current recommendations and its application into clinical practice. KEY MESSAGES The use of levothyroxine in obstetric practices requires a correct diagnosis and to consider the specific recommendations for each thyroid dysfunction entity. The effectiveness and safety of levothyroxine treatment in preventing adverse perinatal events in pregnant women with clinical hypothyroidism is supported by all the current guidelines. Levothyroxine therapy is strongly recommended in all cases of overt hypothyroidism and in cases of subclinical hypothyroidism associated to positive thyroid autoimmunity.

Identifying and treating subclinical thyroid dysfunction in pregnancy: emerging controversies

Thyroid hormones are essential for an adequate growth and development of the fetus. In addition to the classical association between maternal hypothyroidism and neurological impairment in the progeny, other adverse reproductive events have been associated with maternal thyroid dysfunction including infertility, miscarriage and preterm delivery. Although all scientific societies endorse the treatment of overt hypothyroidism; the management and/or treatment of subclinical hypothyroidism, hypothyroxinemia or antithyroid antibody-positive women should be considered with caution. Important trials have found no clear benefit of treatment of subclinical hypothyroidism in terms of cognitive outcomes; however, other interventional studies appear to reduce some of the obstetric and perinatal complications. As a result, the dilemma between universal screening or selective screening of women at high risk of thyroid dysfunction during pregnancy remains unresolved. Despite this, levothyroxine is also now regularly prescribed by gynaecologists and centres for reproductive medicine. In this context, there is increasing concern regarding the risk of over diagnosis and subsequent potential overtreatment. Taken together, we need to reconsider how thyroid dysfunction should be identified in pregnant women and highlight the arguments for and against the use of levothyroxine in obstetric practices. Our main findings: the mismatch between the guidelines recommendations and the use of LT4 in clinical settings as well as the disparity of criteria between scientific societies from different medical specialties. In conclusion, it is essential to reach agreements between both endocrinologists and obstetricians.

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.

Optimal management of hypothyroidism, hypothyroxinaemia and euthyroid TPO antibody positivity preconception and in pregnancy

Normal physiological changes of pregnancy warrant the need to employ gestation specific reference ranges for the interpretation of thyroid function tests. Thyroid hormones play crucial roles in foetal growth and neurodevelopment which are dependent on adequate supply of maternal thyroid hormones from early gestation onwards. The prevention of significant adverse obstetric and neurodevelopmental outcomes from hypothyroidism requires a strategy of empirical levothyroxine dose increases and predictive dose adjustments in pregnancy combined with regular thyroid function testing, starting before pregnancy and until the postpartum period. Subclinical hypothyroidism has been associated with an increased risk of pregnancy loss and neurocognitive deficits in children, especially when diagnosed before or during early pregnancy. Whilst trials of levothyroxine replacement for mild hypothyroidism in pregnancy have not indicated definite evidence of improvements in these outcomes, professional guidelines recommend treatment, especially if evidence of underlying thyroid autoimmunity is present. Studies of isolated hypothyroxinaemia in pregnancy have shown conflicting evidence with regards to adverse obstetric and neurodevelopmental outcomes and no causative relationships have been determined. Treatment of this condition in pregnancy may be considered in those with underlying thyroid autoimmunity. Whilst the evidence for a link between the presence of anti-TPO antibodies and increased risks of pregnancy loss and infertility is compelling, the results of ongoing randomized trials of levothyroxine in euthyroid women with underlying autoimmunity are currently awaited. Further studies to define the selection of women who require levothyroxine replacement and to determine the benefits of a predictive dose adjustment strategy are required.