Effects of Levothyroxine Therapy on Pregnancy Outcomes in Women with Subclinical Hypothyroidism

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.

Screening and management of major endocrinopathies during pregnancy: an update

Endocrinopathies during pregnancy constitute a challenging issue, being prevalent and requiring appropriate management to avoid maternal and fetal complications. This review aims to summarize and present major endocrine problems during pregnancy, the appropriate screening, maternal monitoring and management, fetal monitoring, and follow-up. Glucose metabolism, thyroid function, as well as calcium and vitamin D metabolism are the main endocrine domains that should be screened and monitored during pregnancy. Gestational diabetes mellitus (GDM) is the most prevalent endocrine disease during pregnancy, followed by thyroid disorders. Specific recommendations are provided for the optimal clinical care of pregnant women and their offspring for GDM, thyroid disorders, and calcium and vitamin D disorders.

Effects of Levothyroxine Therapy on Pregnancy and Neonatal Outcomes in Subclinical Hypothyroidism

Purpose

To assess the effects of levothyroxine (LT4) therapy on pregnancy and neonatal outcomes in pregnant women with subclinical hypothyroidism (SCH) who had different thyroid peroxidase antibody (TPOAb) status.

Methods

The data of pregnant women from the Chengdu Hospital of Integrated Traditional Chinese and Western Medicine between January 2017 and August 2019 were collected. SCH was defined as 11.88 < free thyroxine (FT4) < 20.06pmol/L in conjunction with thyroid-stimulating hormone (TSH) >4.00 mU/L. Some clinical characteristics have been collected, including body mass index (BMI) before pregnancy, number of pregnancies, number of miscarriages (spontaneous abortion), parity, family history of diabetes, history of smoking, history of drinking, TSH, FT4, and TPOAb levels. The prevalence of pregnancy and neonatal outcomes in the LT4 and non-LT4 groups, and in the LT4 and euthyroid control groups were compared, respectively. Univariate and multivariate logistic regression analyses were used to assess the effects of LT4 therapy on pregnancy and neonatal outcomes in SCH pregnant women with TPOAb.

Results

A total of 985 subjects were enrolled and divided into LT4 group with 478 patients, non-LT4 group with 156 patients and euthyroid control group with 351 patients. The prevalence of amniotic fluid abnormalities and premature delivery in the LT4 group was lower than that in the non-LT4 group in participants with TPOAb-positive (TPOAb⁺). After adjusting age, BMI prior to pregnancy, number of pregnancies, number of miscarriages, parity, TSH and FT4 level, the SCH pregnant women with TPOAb⁺ in the LT4 group had a lower risk of amniotic fluid abnormalities and premature delivery than that in the non-LT4 group.

Conclusion

LT4 therapy could reduce the risk of premature delivery and amniotic fluid abnormalities in the SCH pregnant women with TPOAb⁺. However, more randomized trials are required to confirm this association before the unequivocal advocacy of LT4 therapy in pregnant women with SCH.

The targeted high-risk case-finding approach versus universal screening for thyroid dysfunction during pregnancy: thyroid-stimulating hormone (TSH) and/or thyroid peroxidase antibody (TPOAb) test?

PURPOSE

To compare the effects of different thyroid screening scenarios, using the universal and targeted high-risk case-finding approaches with different diagnostic tests on the prevalence of subclinical hypothyroidism (SCH), thyroid autoimmunity, and pregnancy outcomes after adjustments for the intervention.

METHODS

During a secondary analysis of data collected in Tehran Thyroid and Pregnancy Study, a total of 2277 women from the total population, including 1303 high-risk individuals for thyroid dysfunction. The Cochran-Mantel-Haenszel method, adjusted for the intervention, was also used to evaluate the relationships between different screening scenarios [i.e., universal approach using thyroid-stimulating hormone (TSH) and/or thyroid peroxidase antibody (TPOAb) tests and targeted high-risk case-finding approach using TSH and/or TPOAb tests] and pregnancy outcomes (i.e., preterm delivery and NICU admission). The universal approach using both TSH and TPOAb measurements was considered as the reference scenario. We analyzed outcomes of different screening methods in individuals treated with LT4, compared to those individuals who were not treated.

RESULTS

Compared to the universal screening approach with both TSH and TPOAb measurements, the targeted high-risk case-finding approach overlooked approximately 42%, 62%, and 74% of women with elevated TSH (> 4 µlU/mL) when using both TSH and TPOAb tests, TSH alone, and TPO alone, respectively. After adjusting for the missed cases, 2.86% of women with preterm delivery and 2.76% of women with NICU admission were missed when they were screened using the targeted high-risk case-finding approach by measuring both TSH and TPOAb. The percentage of missed cases increased when applying the targeted approach with the TSH test alone, without measuring TPOAb. Overall, 4.16% and 4.02% of women with preterm delivery and NICU admission were overlooked in this scenario, respectively. After adjustments for the intervention, the probability of NICU admission in neonates of mothers, who were screened using the targeted high-risk case-finding approach with TPOAb measurement, was 2.31 folds higher than those screened by the reference scenario.

CONCLUSION

This study suggests that although the targeted high-risk case-finding approach including both TSH and TPOAb tests, may overlook some women with SCH, it is a reasonable option since it is not associated with a higher risk of adverse pregnancy outcomes.

Effects of controlled ovarian stimulation on thyroid function during pregnancy

Controlled ovarian stimulation (COS) is a major component of assisted reproductive technologies. Clinically, it has been observed that, some women experience changes in thyrotropin levels following COS, which then bring about subclinical hypothyroidism and may adversely affect conception. Studies have also shown that the specific degree as well as the tendency of changes in thyroid function vary with differences in thyroid function before pregnancy, thyroid autoimmunity, the COS regimen, and the observation time point. However, the associated pathophysiological mechanism of the effects of COS on pregnancy has not yet been fully elucidated. This may be because increased estradiol levels, caused by COS, induce increased levels of thyroxine-binding globulin, resulting in a decrease in free thyroxine (FT4) level and an increase in TSH level. Conversely, it has also been observed that human chorionic gonadotropin (hCG) can act directly on thyroid cells, exerting opposite effects on FT4 and TSH levels. Additionally, the effects of COS on thyroid function may be more pronounced, especially in women with autoimmune thyroid disease or thyroid dysfunction before pregnancy, ultimately leading to subclinical hypothyroidism. Here, we review recent research progress regarding the effects of COS on thyroid function during pregnancy.

Outcomes With Levothyroxine Treatment in Early Pregnancy With Subclinical Hypothyroidism

Introduction

Adverse pregnancy outcomes in women with subclinical hypothyroidism (SCH) are well documented, whereas data regarding the risk and benefit of levothyroxine treatment in such cases are insufficient and inconsistent. Our study aimed to evaluate the effects of levothyroxine treatment on pregnancy outcomes in these women.

Materials and methods

Healthy women with a singleton pregnancy were screened before 12 weeks of gestation for subclinical hypothyroidism using 2017 American Thyroid Association guidelines. They were treated with an initial dose of 50 mcg of levothyroxine and the dose was adjusted at six-week intervals to achieve a normal thyrotropin level. All the participants were followed up with thyroid function tests and ultrasonography till delivery. Pregnancy outcomes were compared with those of healthy pregnant women with normal thyroid function.

Results 

A total of 1058 women were screened and 5.1% (n=54) were found to have subclinical hypothyroidism, out of which 57.4% (n=31) were thyroid peroxidase antibody positive. The median gestational age at the initiation of levothyroxine treatment was nine weeks. The risks for miscarriage (odds ratio (OR): 1.284, p=0.811), gestational hypertension (OR: 1.993, p=0.365), intra-uterine growth restriction (OR: 1.688, p=0.488), low birth weight (OR: 1.591, p=0.392), and preterm birth (OR: 1.606, p=0.529) were not significantly higher in women with subclinical hypothyroidism as compared to euthyroid women. However, the risk of gestational diabetes mellitus was significantly higher in women with SCH (OR: 3.432, 95% confidence interval (95% CI): 1.115-10.562).

Conclusion

Levothyroxine therapy initiated in the first trimester of pregnancy has possible beneficial effects in subclinical hypothyroidism but with a higher risk for gestational diabetes.

Postnatal Serum Total Thyroxine Level Associated with Short- and Long-Term Anthropometric Outcomes in Very Preterm Infants

Thyroxine (T4) importantly regulates the growth of newborns. Compared to fetuses with equivalent gestational ages, very preterm infants (VPIs) often experience relatively low thyroxinemia, with a normal thyroid-stimulating hormone (TSH) concentration < 10 μIU/mL. However, there is continued debate regarding postnatal thyroxine supplementation for VPIs with normal TSH and transitionally low thyroxinemia. Little research has explored the role of the postnatal total T4 (TT4) serum concentration on the growth of VPIs. In this study, we aim to clarify whether the postnatal thyroxine concentration is associated with the short- and long-term growth outcomes of VPIs. A total of 334 surviving VPIs in our previously reported cohort, born in the period August 2007−July 2016, were enrolled. The exposure variable was the postnatal TT4 concentration at 1 month old. The primary outcomes were body weight increments over 28 days after the screening and anthropometric outcomes at the corrected age of 24 months old. Infants with any hormonal replacement, severe brain injury, congenital anomaly, or cerebral palsy were excluded. In total, 290 (86.8%) VPIs were included for analysis. In the 28 days after thyroid function screening, the TT4 concentration was found to have a significant association with positive increments in body weight (mean increment: 25.7 g per 1 μg/dL; p < 0.001) and a positive body weight z-score (mean increment: 0.039 per 1 μg/dL; p = 0.037), determined by generalized estimating equation analysis. At the corrected age of 24 months old, a higher postnatal TT4 concentration was associated with a lower body mass index (mean coefficient: −0.136; 95% CI: −0.231 to −0.041, p = 0.005) and lower body mass index z-score (mean coefficient: −0.097; 95% CI: −0.170 to −0.024, p = 0.009). Infants with a TT4 concentration > 6.4 ug/dL had significantly lower odds of overweight status (odds ratio: 0.365; 95% CI: 0.177 to 0.754, p = 0.006). We conclude that the postnatal TT4 concentration is associated with a positive increment in body weight in the short term. At the same time, the postnatal TT4 concentration is associated with lower odds of overweight status after long-term follow-up.

Use of levothyroxine among pregnant women with subclinical hypothyroidism in the United Kingdom: A population-based assessment

Our study aimed to describe levothyroxine prescription patterns and trends over time among pregnant women with subclinical hypothyroidism (SCH) in the United Kingdom.

We used data from the Clinical Practice Research Datalink linked to its Pregnancy Register and the Hospital Episode Statistics database from 1998 to 2017. The study population included women with a diagnosis of SCH or an abnormal thyroid‐simulated hormone (TSH) level one year prior to or during pregnancy. We compared characteristics between women who received a prescription for levothyroxine during pregnancy and those who did not. We further described the timing, dose, duration, and temporal trends of levothyroxine prescriptions.

Our cohort included 6,757 pregnancies from 6,287 women with SCH, of whom 10% received levothyroxine during pregnancy. Among women who received levothyroxine, most received their first prescription during the first trimester (median gestational age: 7 weeks; interquartile range [IQR]: 0, 16) with a median daily dosage of 50 mcg (IQR: 50, 73). Levothyroxine prescription varied over time, decreasing from 23% of pregnant women in 1998 to 7.5% in 2003, remaining stable until 2014, and increasing to 12.5% in 2016. Smoking, diabetes, polycystic ovary syndrome, infertility, timing of SCH diagnosis, age, TSH level at diagnosis, and general practice regions were associated with prescription.

Few women with SCH received levothyroxine during pregnancy, and treatment varied by patient characteristics and geographical regions. These results highlight the need to increase awareness among healthcare providers and will guide future studies that explore barriers to initiating levothyroxine treatment for women with SCH during pregnancy.

Thyroxine Replacement for Subfertile Females With Subclinical Hypothyroidism and Autoimmune Thyroiditis: A Systematic Review

The second most prevalent endocrine condition affecting women of reproductive age is thyroid disease. The difference between an increased thyroid-stimulating hormone (TSH) concentration and a normal free thyroxine hormone level is used to identify subclinical hypothyroidism. Thyroid autoantibodies, independent of thyroid hormone levels, are used to diagnose autoimmune thyroid disease (ATD). Thyroxine can help infertile women with these two types of thyroid illnesses have better birth outcomes during fertility treatment. We performed a systematic review using PubMed (Medline) as a major database and some other sources EMBASE, the Cochrane Library, Web of Science, Scopus, and Science Direct. We concentrated on four studies, including 806 patients. Our goal is to investigate the efficacy and risks of levothyroxine therapy in infertile women who are receiving fertility treatments and have subclinical hypothyroidism or adequate thyroid function as well as thyroid autoimmunity (euthyroid autoimmune thyroid disorder). Thyroid activity in hypothyroid women should be tracked at pregnancy confirmation and closely monitored during the pregnancy. Early in pregnancy, the dosage of levothyroxine (LT4) can be raised. To ensure optimum TSH levels during breastfeeding, we recommend that patients who are followed in the primary sector have their LT4 dose increased by their general practitioner before their first referral to an endocrinological outpatient clinic. It's important to pay more attention to and track pregnant women with hypothyroidism, who consider pregnancy, to get the best results. LT4 therapy can help subfertile women with subclinical hypothyroidism who are having in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) since it improves embryo growth, implantation rate, and live birth rate.

Laboratory characteristics analysis of the efficacy of levothyroxine on subclinical hypothyroidism during pregnancy: a single-center retrospective study

To reassess the efficacy of levothyroxine on subclinical hypothyroidism (SCH, 4.0 mIU/L ≤ TSH (thyroid stimulating hormone) <10 mIU/L with normal free T4) during pregnancy. 165 levothyroxine-treated pregnant women experiencing SCH were screened. And controls were randomly selected using euthyroidism (EU) women, matched by age, gravidity, and parity in the EU group (n = 660). We evaluated laboratory characteristics and pregnancy outcomes during follow-ups. Compared with the EU group, the SCH group displayed higher inadequate maternal gestational weight gain, premature delivery, low birth weight offspring and infant offspring small for their gestational age. After levothyroxine treatment, the SCH group displayed lower total cholesterol, low-density lipoprotein levels, and higher serum homocysteine levels before delivery. Pregnant women with SCH still exhibit adverse pregnancy outcomes after levothyroxine treatment. Taken together, we believe that besides levothyroxine, vitamin B12 and folic acid could be added to the treatment of pregnant women with SCH. In addition, regular monitoring of blood sugar levels, lipid and homocysteine levels, and intervention gestational weight gain could alleviate the adverse effects of SCH on pregnancy outcomes.

Knowledge, Attitudes, Beliefs, and Treatment Burden Related to the Use of Levothyroxine in Hypothyroid Pregnant Women in the United States

Background: The use of prescribed medications during pregnancy is a challenge and an underestimated source of treatment burden. Levothyroxine (LT4) for the treatment of overt and subclinical hypothyroidism is extensively prescribed during pregnancy. To this end, we aimed to explore the patients' perceived benefits and risks, knowledge, beliefs, attitudes, and related burden of LT4 therapy during pregnancy. Methods: In this cross-sectional study, we surveyed pregnant women who were treated with LT4 during pregnancy from January 1, 2019, to December 31, 2019, in a tertiary academic medical center of the United States. The anonymous online survey included questions to gather demographic data and multiple-choice questions regarding the benefits and risks, knowledge, beliefs, attitudes, and burden related to LT4 use during pregnancy. Results: Sixty-four pregnant women (mean age 31.5 years) completed the study survey (response rate: 96%): 62% were diagnosed with hypothyroidism more than 12 months before pregnancy, 16% less than or about 12 months before pregnancy, and 22% during pregnancy. We found that one-third of pregnant women using LT4 had a feeling of uneasiness/anxiety due to their hypothyroidism diagnosis. About half of the respondents (45%) reported that they did not receive an explanation by their clinician regarding the maternal/fetal risks of uncontrolled hypothyroidism or the benefits of adequate control. Finally, two in three patients expressed various concerns of LT4-related treatment burden. Conclusions: Our findings support the need for increased effective communication and tailored counseling to address fears, anxiety, and uncertainties about the benefits and risks of LT4 use in pregnancy. For patients with clear benefits from LT4 treatment in pregnancy, it could help to overcome their concerns, promote adherence, and decrease adverse maternal/fetal outcomes. For patients with no clear benefits established, clinicians need to be aware of LT4-related treatment burden in pregnancy and implement patient-centered approaches in their clinical practices.

Levothyroxine and the risk of adverse pregnancy outcomes in women with subclinical hypothyroidism: a systematic review and meta-analysis

BACKGROUND

Levothyroxine replacement therapy may decrease the risk of adverse pregnancy outcomes among women with subclinical hypothyroidism (SCH). The aim of this study is to conduct a systematic review and meta-analysis to examine the risk of adverse pregnancy, perinatal, and early childhood outcomes among women with SCH treated with levothyroxine.

METHODS

A systematic literature search was conducted using Ovid-Medline, Ovid-EMBASE, Pubmed (non-Medline), Ebsco-CINAHL Plus with full text and Cochrane Library databases. Randomized controlled studies (RCTs) and observational studies examining the association between treatment of SCH during pregnancy and our outcomes of interest were included. Studies that compared levothyroxine treatment versus no treatment were eligible for inclusion. Data from included studies were extracted and quality assessment was performed by two independent reviewers.

RESULTS

Seven RCTs and six observational studies met our inclusion criteria. A total of 7342 individuals were included in these studies. RCTs demonstrated several sources of bias, with lack of blinding of the participants or research personnel; only one study was fully blinded. In the observational studies, there was moderate to serious risk of bias due to lack of adjustment for certain confounding variables, participant selection, and selective reporting of results. Pooled analyses showed decreased risk of pregnancy loss (RR: 0.79; 95% CI: 0.67 to 0.93) and neonatal death (RR: 0.35; 95% CI: 0.17 to 0.72) associated with levothyroxine treatment during pregnancy among women with SCH. There were no associations between levothyroxine treatment and outcomes during labour and delivery, or cognitive status in children at 3 or 5 years of age.

CONCLUSION

Treatment of SCH with levothyroxine during pregnancy is associated with decreased risks of pregnancy loss and neonatal death. Given the paucity of available data and heterogeneity of included studies, additional studies are needed to address the benefits of levothyroxine use among pregnant women with SCH.

Pregnancy and Neonatal Outcomes With Levothyroxine Treatment in Women With Subclinical Hypothyroidism Based on New Diagnostic Criteria: A Systematic Review and Meta-Analysis

BACKGROUND

Subclinical hypothyroidism (SCH) during pregnancy has been associated with multiple adverse maternal and neonatal outcomes. However, the potential benefits of levothyroxine (LT4) supplementation remain controversial. Variations across studies in diagnostic criteria for SCH may, in part, explain the divergent findings on the subject. This study aimed to assess the effect of LT4 treatment on pregnancy and neonatal outcomes among pregnant women who were diagnosed as SCH based on the most recent diagnostic criteria.

METHODS

We conducted a systematic review and meta-analysis of the literature published from inception to January 2020. The search strategy targeted the studies on pregnancy and neonatal outcomes following LT4 treatment in women with SCH based on 2017 American Thyroid Association diagnostic criteria. Pooled effect sizes were estimated using fixed and random effect models, according to the absence or presence of heterogeneity which was assessed using the I-squared statistic. Sources of heterogeneity and the stability of results were evaluated through sensitivity analysis.

RESULTS

Of the 2781 identified references, 306 full-text articles were screened for eligibility. Finally, 6 studies including a total of 7955 participants were retained for analysis. Summary effect estimates indicated that pregnant women with SCH treated with LT4 had a lower risk of pregnancy loss [odds ratio (OR) = 0.55, 95% confidence interval (CI): 0.43-0.71], preterm birth (OR=0.63, 95% CI: 0.41-0.98) and gestational hypertension (OR = 0.78, 95% CI: 0.63-0.97) than those in control group.

CONCLUSION

LT4 treatment in pregnant women with SCH may reduce the risk of pregnancy loss, preterm delivery and gestational hypertension.

Early Levothyroxine Treatment for Subclinical Hypothyroidism or Hypothyroxinemia in Pregnancy: The St Carlos Gestational and Thyroid Protocol

The optimal maternal levels of thyroid hormones (TH) during the first trimester of gestation have not been established, nor has the ideal moment to initiate levothyroxine treatment (LT) to improve the evolution of gestation and fetal development. Cut-off points for Thyroid-stimulating hormone (TSH) <2.5 µIU/mL and free thyroxine (FT4)>7.5 pg/mL have been recommended. There are no data on whether initiation of LT <9th Gestational Week (GW) can have a favourable impact.

OBJECTIVE

To define the TSH/FT4 percentiles corresponding with 2.5 µIU/mL and 7.5 pg/mL levels, respectively, at GW8 (Study 1), and evaluate the effects of protocol-based LT before GW9 on gestation evolution, in women with TSH ≥2.5 µIU/mL and/or FT4≤ 7.5 pg/mL (study 2).

SUBJECTS

2768 consecutive pregnant women attending the first gestational visit from 2013-2014 and 3026 from 2015-2016 were eligible for Study I and 2 respectively. A final 2043 (study 1) and 2069 (study 2) women were assessed in these studies.

RESULTS

Study 1: The FT4 level of 7.5 pg/mL corresponds with the 17.9th percentile, a TSH level of 2.5 µIU/mL with the 75.8^th. Women with TSH ≥2.5 µIU/mL had a history of fetal losses more frequently than those <2.5 (OR 2.33 (95%CI): 1.58-3.12), as did those with FT4 ≤7.5 pg/ml compared to those >7.5 (OR 4.81; 3.25-8.89). Study 2: A total of 1259 women had optimal TSH/FT4 levels (Group 1), 672 (32.4%, Group 2) had suboptimal TSH or T4l, and 138 (6.7%, Group 3) had suboptimal values of both. 393 (58.5%) in Group 2 and 88 (63.8%) in Group 3 started LT before GW9. Mean (SD) GW24 levels were TSH: 1.96 ± 1.22 µIU/mL and FT4: 7.07 ± 1.25 pg/mL. The highest FT4 value was 12.84 pg/mL. The adjusted risk for an adverse event if LT was started early was 0.71 (0.43-0.91) for Group 2 and 0.80 (0.66-0.94) for Group 3.

CONCLUSIONS

Early LT in women with suboptimum levels of TSH/FT4 (≥2.5µIU/mL/≤7.5 pg/ml) at or before GW9 is safe and improves gestation progression. These data support the recommendation to adopt these cut-off points for LT initiation, which should be started as early as possible.

Thyroid disorders in subfertility and early pregnancy

Disorders of thyroid function are common in pregnancy and have implications for foetal and maternal health. Thyroid autoimmunity, as evidenced by the presence of elevated levels of anti-thyroid antibodies (anti-TPO and anti-Tg antibodies) is associated with an increased risk of miscarriage, though the mechanism remains poorly understood. There has been considerable focus on the implications and optimal management of pregnant women with thyroid disease, especially those undergoing assisted reproduction. Pregnancy results in significant changes in thyroid physiology and these need to be understood by clinicians involved in the care of pregnant women. Guidelines for the use of thyroxine and target thyroid function tests have been produced by international bodies but it is recognised that these predominantly reflect expert opinion rather than established evidence-based practice. Importantly a number of key clinical trials have been performed to aid understanding, particularly of the consequences of hypothyroidism for mother and baby, and the effectiveness of thyroid hormone use in autoimmune and subclinical hypothyroidism. This review summarises the current knowledge base and guidance for practice relating to thyroid disorders in pregnancy and subfertility.

Hypothyroidism and pregnancy: still a controversial issue

Subclinical hypothyroidism (SCH) in pregnancy is common, according to literature, affecting up to 15% of pregnancies. It still represents a controversy weather levothyroxine has beneficial effects on pregnancy outcomes. In this retrospective and prospective cohort study, we assessed fetal and maternal outcomes in women with known thyroid status pre-pregnancy, and hypothyroidism during pregnancy. We included 393 pregnant women, 90 (22.9%) diagnosed with overt and 303 with SCH (77.1%). A total of 94 (56%) had positive anti-TPO antibodies. Levothyroxine substitution across all observational periods was suboptimal, mostly during first trimester in both groups of patients (85.4%). There was a difference in the number of live births in favor of group with SCH (p = .004). Women with overt hypothyroidism were more likely to develop complications during pregnancy (RR = 1.153, 95%CI = 0.775 - 1.714) and had positive TPO-antibodies more often (p = .022). The only significant association was found between fetal outcomes in women with SCH and positive TPO-antibodies (p = .018), while positive Tg-antibodies did not affect the pregnancy outcomes of women with SCH. Moreover, no correlation was observed between outcomes and adequacy of levothyroxine substitution. These results indicate that TPO-antibody positivity could be the most important factor of pregnancy outcomes independent of the TSH levels or adequacy of levothyroxine therapy.

Universal screening for thyroid disease SHOULD NOT be recommended before and during pregnancy

Thyroid dysfunction in pregnancy is strongly associated with adverse maternal and foetal outcomes. The effects of treatment are less clear. There is ongoing discussion on whom to treat, when to treat and whether treatment is beneficial. Although universal screening for thyroid disease during pregnancy increases diagnosis and treatment of thyroid dysfunction, there is currently insufficient evidence demonstrating a positive effect of screening on maternal and foetal outcomes. We therefore, at present, recommend against universal screening for thyroid disease before and during pregnancy.

Effect of levothyroxine supplementation on pregnancy loss and preterm birth in women with subclinical hypothyroidism and thyroid autoimmunity: a systematic review and meta-analysis

BACKGROUND

Subclinical hypothyroidism (SCH) and thyroid autoimmunity (TAI) are associated with adverse pregnancy outcomes such as pregnancy loss and preterm birth. However, the ability of levothyroxine (LT4) supplementation to attenuate the risks of these outcomes remains controversial.

OBJECTIVE AND RATIONALE

This systematic review and meta-analysis was conducted to determine the effect of LT4 supplementation on pregnancy loss rate (PLR) and preterm birth rate (PBR) among pregnant women with SCH and TAI.

SEARCH METHODS

A systematic literature search of the PubMed, EMBASE, Web of Science and Cochrane Controlled Trials Register databases and Clinicaltrials.gov was performed to identify all relevant English studies published up to April 2018. The following terms were used for the search: [subclinical hypothyroidism OR thyroid autoimmunity OR thyroperoxidase antibody (TPO-Ab) OR thyroglobulin antibodies (Tg-Ab)] AND (levothyroxine OR euthyrox) AND [pregnancy outcome OR miscarriage OR abortion OR pregnancy loss OR preterm birth OR premature delivery OR early labo(u)r]. The reference lists of the relevant publications were also manually searched for related studies. Published manuscripts were included if they reported data on pregnancy loss, preterm birth or both. We separately analysed the pooled effects of LT4 supplementation on PLR and PBR in women with SCH and TAI.

OUTCOMES

Overall, 13 eligible studies including 7970 women were included in the meta-analysis. Eight and five of these studies were randomized controlled trials (RCTs) and retrospective studies, respectively. The pooled results indicated that LT4 supplementation significantly decreased the PLR [relative risk (RR) = 0.56, 95% confidence interval (CI): 0.42-0.75, I2 = 1%, 12 studies] and PBR (RR = 0.68, 95% CI: 0.51-0.91, I2 = 21%, eight studies) in women with SCH and/or TAI. We further found that LT4 supplementation significantly decreased the risk of pregnancy loss (RR = 0.43, 95% CI: 0.26-0.72, P = 0.001, I2 = 0%) but not of preterm birth (RR = 0.67, 95% CI: 0.41-1.12, P = 0.13, I2 = 0%) in women with SCH. Furthermore, LT4 supplementation significantly decreased the risks of both pregnancy loss (RR = 0.63, 95% CI: 0.45-0.89, P = 0.009, I2 = 0%) and preterm birth (RR = 0.68 95% CI: 0.48-0.98, P = 0.04, I2 = 46%) in women with TAI. These results were consistent when only RCTs were included in the analysis. Further, in women with SCH, LT4 supplementation reduced the risk of pregnancy loss in pregnancies achieved by assisted reproduction (RR = 0.27, 95% CI: 0.14-0.52, P < 0.001, I2 = 14%) but not in naturally conceived pregnancies (RR = 0.60, 95% CI: 0.28-1.30, P = 0.13, I2 = 0%). By contrast, in women with TAI, LT4 supplementation reduced the risks of both pregnancy loss (RR = 0.61, 95% CI: 0.39-0.96, P = 0.03, I2 = 0%) and preterm birth (RR = 0.49, 95% CI: 0.30-0.79, P = 0.003, I2 = 0%) in naturally conceived pregnancies but not in pregnancies achieved by assisted reproduction (RR = 0.68, 95% CI: 0.40-1.15, P = 0.15, I2 = 0% for pregnancy loss and RR = 1.20, 95% CI: 0.68-2.13, P = 0.53, I2 not applicable for preterm birth).

WIDER IMPLICATIONS

This meta-analysis confirmed the beneficial effects of LT4 supplementation, namely the reduced risks of pregnancy loss and preterm birth, among pregnant women with SCH and/or TAI. The different effects of LT4 supplementation on naturally conceived pregnancies and pregnancies achieved by assisted reproduction in women with SCH and/or TAI suggest that these women should be managed separately. Due to the limited number of studies included in this meta-analysis, especially in the subgroup analysis, further large RCTs and fundamental studies are warranted to confirm the conclusions and better clarify the molecular mechanism underlying these associations.

Associations Between Maternal Thyroid Function in Pregnancy and Obstetric and Perinatal Outcomes

CONTEXT

The effects of maternal subclinical hypothyroidism on pregnancy outcomes are not clear.

OBJECTIVE

We aimed to assess potential associations between maternal thyrotropin (thyroid-stimulating hormone [TSH]) levels in pregnancy and obstetric and perinatal outcomes.

DESIGN

Retrospective cohort study.

SETTING

Tertiary academic medical center.

PATIENTS

Women aged ≥18 years with a singleton gestation and no known thyroid disease seen for prenatal care at Boston Medical Center from January 1, 2003 through May 22, 2014, and their fetuses and infants were included.

MAIN OUTCOME MEASURES

Risk ratios of adverse obstetric and perinatal outcomes.

RESULTS

A total of 8,413 pregnant women (mean age 29.1 years, 15% white, 60% black, 13% Hispanic) and their fetuses and infants (mean gestational age at birth 38.5 weeks, 52% male, mean birth weight 3.2 kg) were included in the analyses. The median (interquartile range) TSH level was 1.06(0.62-1.60) mIU/L, and 130 women (1.6%) had TSH > 4 mIU/L. Maternal TSH levels > 4 mIU/L were associated with increased risks of prematurity (risk ratio [RR] 2.17 [95% confidence interval 1.15-4.07] P = .016) and neonatal respiratory distress syndrome (RDS) (RR 2.83 [95% confidence interval 1.02-7.86] P = .046) compared to TSH levels ≤ 4 mIU/L. Although not statistically significant, TSH levels > 4 mIU/L were also associated with increased RRs for fetal loss, preeclampsia/eclampsia, and low birth weight. TSH levels > 4 mIU/L were not associated with preterm labor, placental abruption, cesarean section, gestational hypertension or diabetes, or neonatal intensive care unit admission.

CONCLUSION

Maternal serum TSH concentration > 4 mIU/L in pregnancy was associated with approximately 2-fold increased risks of prematurity and RDS in offspring. Elevated TSH was also associated with statistically non-significant increases in the risk of fetal loss, preeclampsia/eclampsia, and low birth weight.

Study on subclinical hypothyroidism in pregnancy: a bibliometric analysis via CiteSpace

Background: Subclinical hypothyroidism (SCH) in pregnancy has drawn an increasing amount of attention over the past two decades. However, the definition of it, including its clinical diagnosis and treatment, is still being revised. An increased risk of adverse pregnancy outcomes have been shown in most but not all studies. The objective of this study was to evaluate the origin, current trend and research hotspots on SCH in pregnancy.Methods: We obtained 630 records with 12,033 references, published between 1999 and 2018, from the online version of SCI-Expanded, Thomson Reuters Web of Science. The CiteSpace 5.3.R4 was used to perform the cooperation network analysis, key words co-occurrence and burst detection analysis, and reference cocitation analysis.Results: We identified that the number of publications on SCH in pregnancy was increasing over the past two decades. Teng WP and Shan ZY from the First Hospital of China Medical University, Shenyang, China, were found to be the most productive researchers in this field. USA was the leading country for publications. Subclinical hypothyroidism, pregnancy, hypothyroidism, dysfunction, disease, management, women, deficiency, association and hyperthyroidism were the top 10 high frequency keywords in all recruit documents. Follow up was the most strength burst key word in this field from 1999 through 2018, followed by maternal hypothyroxinemia, child, hypothyroidism complicating pregnancy, antithyroid antibody and fetal. Moreover, cocitation reference analysis revealed the top landmark articles and clusters in this field.Conclusion: This study provides the trends and frontiers in the field of SCH in pregnancy and valuable information for endocrine and/or obstetric researchers to identify new perspectives on potential collaborators and cooperative countries.

Levothyroxine supplementation in hypothyroid bitches during pregnancy

Hypothyroidism is the most common endocrine disease in dogs and has been shown to have a hereditary nature in many breeds. Previous studies have documented decreased fertility in bitches with experimentally-induced hypothyroidism, decreased viability at birth, increased periparturient mortality, and reduced birth weight in pups born to hypothyroid dogs. Hypothyroid women have an increased demand for exogenous thyroxine throughout gestation in order to maintain normal plasma concentrations of thyroid hormones and produce neuropsychologically normal children. This study was performed to determine if pregnancy causes a similar need for increased levothyroxine dosages in dogs to maintain a euthyroid state. Serum was harvested from blood collected from six bitches with experimentally-induced hypothyroidism that were receiving standard thyroid hormone replacement therapy and from four euthyroid control bitches. Thyroid function tests performed on these samples included total thyroxine (T₄), free T₄ (fT₄), thyroid stimulating hormone (TSH), and 3,5,3'-triiodothyronine (T₃). Thyroid function tests were measured from ovulation through the end of pregnancy. All bitches whelped normal litters. Euthyroid bitches had no significant alterations in their hormone concentrations throughout pregnancy. None of the supplemented hypothyroid bitches had clinical signs of hypothyroidism throughout the study. Serum concentrations of T₄ and fT₄ were elevated compared to ovulation at multiple sample points during gestation in supplemented dogs. The results from this study indicate that standard levothyroxine supplementation is adequate to maintain a euthyroid state during pregnancy in experimentally-induced hypothyroid dogs. In addition, there is no evidence that canine thyroid profiles in euthyroid dogs are altered during gestation.

Hospitalization before and after delivery in fertile, subfertile, and ART-treated women

PURPOSE

Pre-pregnancy and post-delivery hospitalizations were compared as markers for health among women who conceived using assisted reproductive technology (ART), non-ART medically assisted reproduction (MAR), no treatment (unassisted subfertile), and who were fertile.

METHODS

We analyzed hospital discharge data linked to Massachusetts birth certificates from 2004 to 2013 within 5 years prior to pregnancy and 8-365 days post-delivery. ART deliveries were linked from a national ART database; MAR deliveries had fertility treatment but not ART; unassisted subfertile women had subfertility but no ART or MAR; and fertile women had none of these. Prevalence of diagnoses during hospitalization was quantified. Multivariable logistic regression models with fertile deliveries as reference were adjusted for maternal age, race, education, year, and plurality (post-delivery only) with results reported as adjusted odds ratios (AORs) and 95% confidence intervals (CI).

RESULTS

Of 170,605 privately insured, primiparous deliveries, 10,458 were ART, 3005 MAR, 1365 unassisted subfertile, and 155,777 fertile. Pre-pregnancy hospitalization occurred in 6.8% and post-delivery in 2.8% of fertile women. Subfertile groups had more pre-pregnancy hospitalizations (AOR, 95% CI: 1.84, 1.72-1.96 ART; 1.41, 1.24-1.60 MAR; 3.02, 2.62-3.47 unassisted subfertile) with endometriosis, reproductive organ disease, ectopic pregnancy/miscarriage, and disorders of menstruation, ovulation, and genital tract being common. Post-delivery hospitalizations were significantly more frequent in the ART (AOR 1.19, 95% CI 1.05-1.34) and unassisted subfertile (1.59, 1.23-2.07) groups with more digestive tract disorders, thyroid problems, and other grouped chronic disease conditions.

CONCLUSIONS

Greater likelihood of hospitalization in the ART, MAR, and unassisted subfertile groups is largely explained by admissions for conditions associated with subfertility.

Levothyroxine treatment and pregnancy outcomes in women with subclinical hypothyroidism: a systematic review and meta-analysis

PURPOSE

To evaluate the benefits of LT4 treatment on pregnancy outcomes in SCH women.

STUDY DESIGN

PubMed [including Medline], Web of Science, Wiley, Google Scholar, Science direct and Scopus were searched for identifying and retrieving all English articles published up to May 2018 on the effects of levothyroxine treatment on pregnancy outcomes in pregnant women with SCH compared to untreated or healthy controls. In this systematic review and meta-analysis, both fixed and random effect models were applied to estimate the pooled effect size. Heterogeneity and publication bias were evaluated using the I-squared (I²) and Begg's statistics, respectively. We also explored heterogeneity sources using meta-regression models and sensitivity analysis.

RESULTS

Data of 13 cohort studies and randomized controlled trials with a total of 11,503 participants were analyzed. This meta-analysis showed that pregnant women with SCH treated with levothyroxine had lower chances of pregnancy loss (OR 0.78, 95% CI 0.66-0.94; I² = 0%) and higher chances for live birth rates (OR 2.72, 95% CI 1.44-5.11; I² = 25%) than the placebo group. Compared to euthyroid women, SCH patients treated with levothyroxine had higher odds ratio for preterm labor (OR 1.82, 95% CI 1.14-2.91; I² = 0%).

CONCLUSIONS

Results of this study showed that the effects of treatment with levothyroxine in SCH pregnant women are not the same for all pregnancy outcomes. Levothyroxine treatment in these patients can reduce pregnancy loss. Considering the limited number of studies available, further studies are warranted to document more precise data on other consequences.

Thyroxine replacement for subfertile women with euthyroid autoimmune thyroid disease or subclinical hypothyroidism

BACKGROUND

Thyroid disease is the second most common endocrine disorder affecting women of reproductive age. Subclinical hypothyroidism is diagnosed by an elevated thyroid-stimulating hormone concentration with a normal concentration of free thyroxine hormone. Autoimmune thyroid disease (ATD) is diagnosed by the presence of thyroid autoantibodies, regardless of thyroid hormone levels. Thyroxine may be a useful treatment for subfertile women with these two specific types of thyroid disease for improving pregnancy outcomes during assisted reproduction.

OBJECTIVES

To evaluate the efficacy and harms of levothyroxine replacement in subfertile women with subclinical hypothyroidism or with normal thyroid function and thyroid autoimmunity (euthyroid autoimmune thyroid disease, or euthyroid ATD) undergoing assisted reproduction.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility (CGF) Group specialised register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL and two trials registers together with reference checking and contact with study authors and experts in the field to identify studies. We searched for all published and unpublished randomised controlled trials (RCTs) comparing thyroxine with no treatment or placebo, without language restrictions, from inception to 8 April 2019, and in consultation with the Cochrane CGF Information Specialist.

SELECTION CRITERIA

We included women undergoing assisted reproduction treatment, meaning both in vitro fertilisation and intracytoplasmic sperm injection, with a history of subfertility and with subclinical hypothyroidism or with euthyroid ATD. We excluded women with a previously known clinical hypothyroidism or already taking thyroxine or tri-iodothyronine. RCTs compared thyroxine (levothyroxine) with either placebo or no treatment.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our primary review outcomes were live birth and adverse events of thyroxine; our secondary outcomes were clinical pregnancy, multiple pregnancy and miscarriage.

MAIN RESULTS

The review included four studies with 820 women. The included studies were of overall low risk of bias. Using GRADE methodology, we assessed the quality of evidence for the primary outcomes of this review to be very low- to low-quality evidence. Evidence was downgraded for imprecision as it was based on single, small trials with wide confidence intervals (CI). We were able to include data from three of the four included studies.In one study of women with both subclinical hypothyroidism and positive or negative anti-TPO antibodies (autoimmune disease), the evidence suggested that thyroxine replacement may have improved live birth rate (RR 2.13, 95% CI 1.07 to 4.21; 1 RCT, n = 64; low-quality evidence) and it may have led to similar miscarriage rates (RR 0.11, 95% CI 0.01 to 1.98; 1 RCT, n = 64; low-quality evidence). The evidence suggested that women with both subclinical hypothyroidism and positive or negative anti-TPO antibodies would have a 25% chance of a live birth with placebo or no treatment, and that the chance of a live birth in these women using thyroxine would be between 27% and 100%.In women with normal thyroid function and thyroid autoimmunity (euthyroid ATD), treatment with thyroxine replacement compared with placebo or no treatment may have led to similar live birth rates (risk ratio (RR) 1.04, 95% CI 0.83 to 1.29; 2 RCTs, number of participants (n) = 686; I² = 46%; low-quality evidence) and miscarriage rates (RR 0.83, 95% CI 0.47 to 1.46, 2 RCTs, n = 686, I² = 0%; low-quality evidence). The evidence suggested that women with normal thyroid function and thyroid autoimmunity would have a 31% chance of a live birth with placebo or no treatment, and that the chance of a live birth in these women using thyroxine would be between 26% and 40%.Adverse events were rarely reported. One RCT reported 0/32 in the thyroxine replacement group and 1/32 preterm births in the control group in women diagnosed with subclinical hypothyroidism and positive or negative anti-TPO antibodies. One RCT reported 21/300 preterm births in the thyroxine replacement group and 19/300 preterm births in the control group in women diagnosed with positive anti-TPO antibodies. None of the RCTs reported on other maternal pregnancy complications, foetal complications or adverse effects of thyroxine.

AUTHORS' CONCLUSIONS

We could draw no clear conclusions in this systematic review due to the very low to low quality of the evidence reported.

Variation in treatment practices for subclinical hypothyroidism in pregnancy: US national assessment

CONTEXT

Although thyroid hormone replacement may improve outcomes in pregnant women with subclinical hypothyroidism (SCH), the extent to which they receive treatment is unknown.

OBJECTIVE

To describe levothyroxine (LT4) treatment practices for pregnant women with SCH.

DESIGN

Retrospective cohort study.

SETTING

Large U.S. administrative claims database.

PARTICIPANTS

Pregnant women with SCH defined by untreated TSH 2.5-10 mIU/L.

MAIN OUTCOME MEASURE

Initiation of LT4 as a function of treating clinician specialty (endocrinology, obstetrics/gynecology, primary care, or other), baseline TSH, patient clinical and demographic factors, and U.S. region.

RESULTS

We identified 7,990 pregnant women with SCH; only 1,214 (15.2%) received LT4. Treatment was significantly more likely in patients with higher TSH, obesity, recurrent pregnancy loss, thyroid disease, and cared by endocrinologists. Proportion of treated women increased over time; LT4 treatment was twice as likely in 2014 as in 2010. Women in Northeast and West U.S. were significantly more likely to receive LT4 compared to other regions. Asian women were more likely, while Hispanic women were less likely, to receive LT4 compared to White women. Endocrinologists started LT4 at lower TSH thresholds than other specialties, and treated women who were more likely to have had recurrent pregnancy loss and thyroid disease than women treated by other clinicians.

CONCLUSIONS

We found large variation in the prescription of LT4 to pregnant women with SCH, though most treatment-eligible women remained untreated. Therapy initiation is associated with geographic, clinician, and patient characteristics. This evidence can inform quality improvement efforts to optimize care for pregnant women with SCH.

Thyroid function and thyroid disorders during pregnancy: a review and care pathway

PURPOSE

To review the literature on thyroid function and thyroid disorders during pregnancy.

METHODS

A detailed literature research on MEDLINE, Cochrane library, EMBASE, NLH, ClinicalTrials.gov, and Google Scholar databases was done up to January 2018 with restriction to English language about articles regarding thyroid diseases and pregnancy.

RESULTS

Thyroid hormone deficiencies are known to be detrimental for the development of the fetus. In particular, the function of the central nervous system might be impaired, causing low intelligence quotient, and mental retardation. Overt and subclinical dysfunctions of the thyroid disease should be treated appropriately in pregnancy, aiming to maintain euthyroidism. Thyroxine (T4) replacement therapy should reduce thyrotropin (TSH) concentration to the recently suggested fixed upper limits of 2.5 mU/l (first and second trimester) and 3.0 mU/l (third trimester). Overt hyperthyroidism during pregnancy is relatively uncommon but needs prompt treatment due to the increased risk of preterm delivery, congenital malformations, and fetal death. The use of antithyroid drug (methimazole, propylthiouracil, carbimazole) is the first choice for treating overt hyperthyroidism, although they are not free of side effects. Subclinical hyperthyroidism tends to be asymptomatic and no pharmacological treatment is usually needed. Gestational transient hyperthyroidism is a self-limited non-autoimmune form of hyperthyroidism with negative antibody against TSH receptors, that is related to hCG-induced thyroid hormone secretion. The vast majority of these patients does not require antithyroid therapy, although administration of low doses of β-blocker may by useful in very symptomatic patients.

CONCLUSIONS

Normal maternal thyroid function is essential in pregnancy to avoid adverse maternal and fetal outcomes.

Levothyroxine supplementation on assisted reproduction technology (ART) outcomes in women with subtle hypothyroidism: a retrospective study

The need for treating subclinical hypothyroidism (SCH) in women undergoing assisted reproduction technology (ART) is under debate. Moreover, it is known that controlled ovarian hyperstimulation (COH) protocols may impair the thyroidal axis. Therefore, we evaluated if levothyroxine (L-T4) supplementation in SCH women before undergoing ART positively affects the main reproductive outcomes. We retrospectively analyzed in vitro fertilization (IVF) data of 4147 women submitted to 6545 cycles in a tertiary care IVF Center (January 2009-December 2014). L-T4 (1.4-2.0 mcg/kg) treatment was offered to all women with a pre-cycle TSH >2.5 mIU/L before starting COH and main ART outcomes were compared in euthyroid and L-T4-treated women undergoing ART. Among 4147 women, 1074 (26%) were affected by SCH and were treated with L-T4 before COH was started. No statistically significant differences among L-T4-treated and euthyroid women group were observed regarding pregnancy rate, respectively, per cycle (27.67% vs 26.37%; p = .314) and per embryo transfer (30.13% vs 29.17%; p = .489), live birth rate, respectively, per cycle (21.58% vs 20.38%; p = .304) and per embryo transfer (23.49 vs 22.54%; p = .449) and the rest of primary and secondary efficacy endpoints. Early L-T4 treatment for infertile women with a subtle thyroid dysfunction may mitigate and protect from the negative effects of SCH in the setting of ART, and may preventively overcome also the negative impact of COH on thyroidal axis.

Initiation timing effect of levothyroxine treatment on subclinical hypothyroidism in pregnancy

The aim of this study is to estimate the timing impact on levothyroxine replacement among pregnant women with subclinical hypothyroidism (SCH). Ninety-eight pregnant women diagnosed as SCH in the first trimester were randomly divided into three groups: Group A, instantly initiated levothyroxine after diagnosis; Group B, administrated treatment in the second trimester, and Group C, received no prescription. Incidence of pregnancy complications and pregnancy outcomes were compared among three groups and subgroup analysis were performed stratified with TPO status in Group B. Group A exhibited lower rate of pregnancy complications (9.7%) and adverse outcome (3.2%) than Group B (41.9% and 32.3%) and Group C (64.5% and 38.7%). But the late initiation treatment group shared a comparable complication and maternal outcome with untreated women (p = .075 and .596, respectively). After stratified with TPOAb status in Group B, TPOAb⁺ women experienced a remarkable lower complication (14.2%) and adverse outcome rate (7.1%) compared with negative subjects (64.7% and 45%, respectively). Our data suggest that levothyroxine administrated in the first trimester was associated with decreased risk of adverse obstetric event. Additionally, pregnant women with TPOAb positive could also benefit from thyroid hormone therapy even initiated in the second trimester.

Effect of levothyroxine supplementation on pregnancy outcomes in women with subclinical hypothyroidism and thyroid autoimmuneity undergoing in vitro fertilization/intracytoplasmic sperm injection: an updated meta-analysis of randomized controlled trials

BACKGROUND

Evidence suggests that subclinical hypothyroidism (SCH) and thyroid autoimmunity (TAI) are associated with adverse pregnancy outcomes. This systematic review and meta-analysis was conducted to determine whether levothyroxine (LT4) supplementation would improve pregnancy outcomes among infertile women with SCH and/or TAI who underwent in vitro fertilization (IVF) or intracytoplastic sperm injection (ICSI).

METHODS

We searched databases of PubMed, EMBASE, Web of Science, Cochrane Controlled Trials Register databases, and Clinicaltrials.gov up to April 2018 to identify eligible studies. Studies that focused on the treatment effect of LT4 on pregnancy outcomes of women with SCH and/or TAI who underwent IVF/ICSI were included in the data synthesis. We only included randomized controlled trials (RCTs). Relative risks (RR) and 95% confidence intervals (CI) were calculated using a random-effects model to assess the results of pregnancy outcomes, including clinical pregnancy rate, miscarriage rate, live birth rate and preterm birth rate.

RESULTS

Four published RCTs including 787 infertile couples undergoing IVF/ICSI were included in this meta-analysis. Notably, the study observed no significant associations of LT4 treatment with the clinical pregnancy rate (RR = 1.46, 95% CI: 0.86-2.48), live birth rate (RR = 2.05, 95% CI: 0.96-4.36), or preterm birth rate (RR = 1.13, 95% CI: 0.65-1.96). However, patients receiving LT4 supplementation had a significantly decreased miscarriage rate relative to those receiving a placebo or no treatment (RR = 0.51, 95% CI: 0.32-0.82). A further sub-group analysis showed that LT4 supplementation did not improve the miscarriage rates among patients with SCH (RR = 0.67, 95% CI: 0.39-1.15) or TAI (RR = 0.28, 95% CI: 0.07-1.06).

CONCLUSIONS

Given its potential to reduce the miscarriage rate, LT4 supplementation is recommended for infertile women with SCH and/or TAI who are undergoing IVF/ICSI. However, additional population-based RCTs are needed to confirm this recommendation.

Prevalence of subclinical hypothyroidism in pregnancy in Saudi Arabia

objectives:

To estimate the prevalence of subclinical hypothyroidism (SCH) in Saudi Arabia and assess the need for an SCH screening program.

Methods:

This cross-sectional study was conducted at King Abdulaziz Medical City and the Khashmulaan Clinic at the National Guard Health Affairs, Riyadh, Saudi Arabia in August 2016. All women attending the antenatal clinics were invited to participate in the study. In addition, data were retrieved from the files of pregnant women who had been screened for hypothyroidism from January 2016 to August 2016. A total of 384 pregnant women were included in the study.

Results:

The prevalence of SCH in pregnant women in this study was 50/384 (13%) with 95% confidence intervals (CIs): 9.82%-16.80%. Pregnant women who were randomly screened using a survey (n=127) were 3 times more likely (OR: 3.1; 95% CI: 1.182 to 8.704, p=0.022) to have SCH compared to pregnant women who were screened based on their physician’s judgement (n=257). Results showed older age (≥40 years) was associated with an insignificant decrease in the risk of SCH.

Conclusion:

Random screening for SCH in pregnant women showed a higher prevalence in comparison to women who were screened as a result of physician referrals. The results highlight the urgent need for larger studies to investigate the prevalence of SCH as well as the need for an SCH screening program.

Impact of levothyroxine therapy on obstetric, neonatal and childhood outcomes in women with subclinical hypothyroidism diagnosed in pregnancy: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To determine in women with subclinical hypothyroidism diagnosed in pregnancy whether levothyroxine treatment compared with control, impacts important obstetrical or childhood outcomes (specifically IQ) in randomised controlled trials.

DESIGN

Systematic review and meta-analysis.

STUDY ELIGIBILITY CRITERIA

Randomised trials which met all the following were included: (1) reported original data of women with subclinical hypothyroidism diagnosed in pregnancy (by any prespecified study definition); (2) randomised to either levothyroxine or control (placebo or no treatment); (3) reported obstetrical outcomes and/or childhood neurodevelopmental outcomes and (4) published from 1980 to January 2018 in either English or French language.

DATA SOURCES

Medline, EMBASE, CINAHL, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials and ClinicalTrials.gov.

OUTCOME MEASURES

Obstetrical, neonatal and childhood outcomes including: miscarriage, gestational hypertension, pre-eclampsia, preterm delivery, mode of delivery, neonatal intensive care unit admission, birth weight, gestational age at delivery, childhood IQ and neurodevelopmental scores. Risk of bias assessment Cochrane Risk of Bias Tool (Modified) for Quality Assessment of Randomised Controlled Trials RESULTS: Three trials of low to unclear risk of bias with 1837 participants were included. Two studies were meta-analysed for maternal and neonatal outcomes and two studies for childhood IQ. No statistically significant differences were found for any clinical outcomes with levothyroxine therapy compared with control.

LIMITATIONS

Only three trials were identified for inclusion.

CONCLUSIONS

This review, based on three randomised trials in women with subclinical hypothyroidism diagnosed in pregnancy, found no evidence of benefit of levothyroxine therapy on obstetrical, neonatal, childhood IQ or neurodevelopmental outcomes. Current trial evidence does not support the treatment of subclinical hypothyroidism diagnosed in pregnancy.

PROSPERO REGISTRATION NUMBER

CRD4201707980.

Subclinical Hypothyroidism in Women Planning Conception and During Pregnancy: Who Should Be Treated and How?

Subclinical hypothyroidism (SCH), a mild form of hypothyroidism defined as elevated TSH with normal free thyroxine levels, is a common diagnosis among women of reproductive age. In some, but not all, studies, it has been associated with infertility, an increased risk of adverse pregnancy and neonatal outcomes, and possibly with an increased risk of neurocognitive deficits in offspring. Despite well-established recommendations on treatment of overt hypothyroid pregnant women, a consensus has not yet been reached on whether to treat women with SCH. This review focuses on examining the evidence informing the clinical strategy for using levothyroxine (LT4) in women with SCH during pregnancy and those who are planning conception. A crucial first step is to accurately diagnose SCH using the appropriate population-based reference range. For pregnant women, if this is unavailable, the recommended TSH upper normal limit cutoff is 4.0 mIU/L. There is evidence supporting a decreased risk for pregnancy loss and preterm delivery for pregnant women with TSH > 4.0 mIU/L receiving LT4 therapy. LT4 treatment has been associated with better reproductive outcomes in women with SCH undergoing artificial reproductive techniques, but not in those who are attempting natural conception. Thyroid function tests need to be repeated throughout pregnancy to monitor LT4 therapy. In addition to potential harms, LT4 contributes to treatment burden. During a consultation, clinicians and patients should engage in a careful consideration of the current evidence in the context of the patients’ values and preferences to determine whether LT4 therapy initiation is the best next step.

Maternal hypothyroidism in the perinatal period and childhood asthma in the offspring

BACKGROUND

There is increasing interest in the possible link between maternal hypothyroidism in the perinatal period and childhood asthma risk. We explored this in this study while accounting for the timing of hypothyroidism diagnosis. Further, we evaluated whether the risk was moderated by thyroid hormone treatment during pregnancy.

METHODS

We conducted a population-based cohort study using Danish national registers. All live-born singletons in Denmark from 1998 to 2007 were identified. Maternal hypothyroidism and asthma in the children were defined by data from the Patient Register and Prescription Registry. We estimated incidence rate ratios (IRRs) of asthma among children born to hypothyroid mothers versus children born to mothers with no recorded thyroid dysfunction using Poisson regression models.

RESULTS

Of 595 669 children, 3524 children were born to mothers with hypothyroidism diagnosed before delivery and 4664 diagnosed after delivery. Overall, 48 990 children received treatment for asthma. The IRRs of asthma was 1.16 (95% confidence interval (CI): 1.03-1.30) and 1.12 (95% CI: 1.02-1.24) for children born to mothers with hypothyroidism diagnosed before and after delivery, compared to children born to mothers with no thyroid dysfunction. The highest risk was observed among children born to mothers with hypothyroidism diagnosed before delivery who did not receive thyroid hormone treatment during pregnancy (IRR=1.37, 95% CI: 1.04-1.80).

CONCLUSION

Our findings suggest that maternal hypothyroidism, especially when it is untreated, increases childhood asthma risk. Early detection and appropriate treatment of hypothyroidism in pregnant women may be an area for possible prevention of childhood asthma.

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.

Subclinical Hypothyroidism in Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis

Background: The association between subclinical hypothyroidism (SCH) and polycystic ovary syndrome (PCOS) has been reported in several studies, but it is not well-recognized. The aim of this study was to evaluate the prevalence of SCH in women with PCOS. Methods: An extensive literature search was conducted in PubMed, Embase, Web of Science, and Cochrane Library databases. All articles published before May 2018 was considered for eligibility. No language restrictions were implemented. The prevalence of SCH in PCOS was calculated by the meta-analysis to produce an odds ratio (OR) with 95% confidence interval (CI). Results: A total of 6 studies including 692 PCOS patients and 540 controls were eligible for the meta-analysis. The combined odds ratio (OR) of SCH risk for women with PCOS compared with controls was 2.87 (95% CI = 1.82-9.92; P < 0.000001). The OR increased to 3.59 when limiting thyroid stimulating hormone (TSH) cut-off to ≥4 mIU/L. Conclusions: Women with PCOS are more likely to develop SCH.

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.

Preconception TSH and pregnancy outcomes: a population-based cohort study in 184 611 women

BACKGROUND

Whether subclinical hypothyroidism adversely impacts pregnancy outcomes is inconclusive, and limited data are available on the optimal TSH range in women planning pregnancy.

OBJECTIVE

To investigate the association between maternal preconception TSH levels and pregnancy outcomes.

DESIGN

Population-based cohort study.

METHODS

From 2010 to 2012, the free National Pre-pregnancy Checkups Project recruited 248 501 pairs of volunteer couples across China, of which 184 611 women, who subsequently became pregnant, were studied. Maternal TSH was measured within 6 months prior to conception. Participants were grouped according to TSH: 0·48-2·49 mIU/l (n = 133 232, 72%), 2·50-4·28 mIU/l (n = 44 239, 24%) and 4·29-10·0 mIU/l (n = 7140, 4%). Multivariable logistic regression models were used to study the association between TSH and pregnancy outcomes.

MAIN OUTCOMES

Pregnancy loss, gestational age (GA), delivery modes and birthweight.

RESULTS

The overall incidence of adverse pregnancy outcomes was 28·6%. Compared with TSH 0·48-2·50 mIU/l, TSH 2·50-4·29 mIU/l was associated with spontaneous abortion [aOR: 1·10, 95% confidence interval (CI): 1·03-1·18], preterm birth (aOR: 1·09, 95% CI: 1·04-1·15) and operative vaginal delivery (aOR: 1·15, 95% CI: 1·09-1·21), while TSH 4·29-10 mIU/l was correlated with spontaneous abortion (aOR: 1·15, 95% CI: 1·10-1·22), stillbirth (aOR: 1·58, 95% CI: 1·10-2·28), preterm birth (aOR: 1·20, 95% CI: 1·08-1·34), caesarean section (aOR: 1·15, 95% CI: 1·10-1·22) and large for gestational age (LGA) infants (aOR: 1·12, 95% CI: 1·04-1·21).

CONCLUSION

Preconception TSH elevation was associated with increased risk of adverse pregnancy outcomes, even within the normal nonpregnant range.

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.

Thyroid hormone treatment among pregnant women with subclinical hypothyroidism: US national assessment

OBJECTIVE

 To estimate the effectiveness and safety of thyroid hormone treatment among pregnant women with subclinical hypothyroidism.

DESIGN

 Retrospective cohort study.

SETTING

 Large US administrative database between 1 January 2010 and 31 December 2014.

PARTICIPANTS

 5405 pregnant women with subclinical hypothyroidism, defined as untreated thyroid stimulating hormone (TSH) concentration 2.5-10 mIU/L.

EXPOSURE

 Thyroid hormone therapy.

MAIN OUTCOME MEASURE

 Pregnancy loss and other pre-specified maternal and fetal pregnancy related adverse outcomes.

RESULTS

 Among 5405 pregnant women with subclinical hypothyroidism, 843 with a mean pre-treatment TSH concentration of 4.8 (SD 1.7) mIU/L were treated with thyroid hormone and 4562 with a mean baseline TSH concentration of 3.3 (SD 0.9) mIU/L were not treated (P<0.01). Pregnancy loss was significantly less common among treated women (n=89; 10.6%) than among untreated women (n=614; 13.5%) (P<0.01). Compared with the untreated group, treated women had lower adjusted odds of pregnancy loss (odds ratio 0.62, 95% confidence interval 0.48 to 0.82) but higher odds of preterm delivery (1.60, 1.14 to 2.24), gestational diabetes (1.37, 1.05 to 1.79), and pre-eclampsia (1.61, 1.10 to 2.37); other pregnancy related adverse outcomes were similar between the two groups. The adjusted odds of pregnancy loss were lower in treated women than in untreated women if their pre-treatment TSH concentration was 4.1-10 mIU/L (odds ratio 0.45, 0.30 to 0.65) but not if it was 2.5-4.0 mIU/L (0.91, 0.65 to 1.23) (P<0.01).

CONCLUSION

 Thyroid hormone treatment was associated with decreased risk of pregnancy loss among women with subclinical hypothyroidism, especially those with pre-treatment TSH concentrations of 4.1-10 mIU/L. However, the increased risk of other pregnancy related adverse outcomes calls for additional studies evaluating the safety of thyroid hormone treatment in this patient population.