Overt and subclinical hypothyroidism complicating pregnancy

The effects of maternal thyroid hormone function on early pregnancy

PURPOSE OF REVIEW

It is unclear whether pregnancy outcomes are impacted by nonovert thyroid disease, and whether detection and treatment of abnormalities improve outcomes. Consequently, there is an ongoing debate regarding universal thyroid screening in pregnancy. A lack of solid evidence has prompted researchers to evaluate the role of screening and to examine pregnancy outcomes in women with thyroid dysfunction. In addition, as IVF has developed into a commonly used procedure, its impact on thyroid function has also been investigated. The most current literature on these topics will be summarized in this review.

RECENT FINDINGS

The multiple societies that have published guidelines on thyroid disease in pregnancy have developed different recommendations, with none definitively advocating for universal screening at this time. However, recent studies examining the role of screening have supported it from an economic and prevalence standpoint. Despite this, evidence has failed to consistently demonstrate that treatment of nonovert thyroid disorders improves maternal and fetal outcomes. Recent research does suggest that close monitoring for and treatment of thyroid dysfunction is warranted in women undergoing IVF.

SUMMARY

Further research must be performed to determine whether treatment of nonovert thyroid disease during pregnancy impacts outcomes. Concrete evidence will likely influence the universal screening debate.

Fetal exposure to nonsteroidal anti-inflammatory drugs and spontaneous abortions

BACKGROUND

Spontaneous abortion is the most common complication of pregnancy. Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used during pregnancy. Published data are inconsistent regarding the risk of spontaneous abortion following exposure to NSAIDs.

METHODS

We performed a historical cohort study involving all women who conceived between January 2003 and December 2009 and who were admitted for delivery or spontaneous abortion at Soroka Medical Center, Clalit Health Services, Israel. A computerized database of medication dispensation was linked with 2 computerized databases containing information on births and spontaneous abortions. We constructed time-varying Cox regression models and adjusted for maternal age, diabetes mellitus, hypothyroidism, obesity, hypercoagulation or inflammatory conditions, recurrent miscarriage, in vitro fertilization of the current pregnancy, intrauterine contraceptive device, ethnic background, tobacco use and year of admission.

RESULTS

The cohort included 65,457 women who conceived during the study period; of these, 58,949 (90.1%) were admitted for a birth and 6508 (9.9%) for spontaneous abortion. A total of 4495 (6.9%) pregnant women were exposed to NSAIDs during the study period. Exposure to NSAIDs was not an independent risk factor for spontaneous abortion (nonselective cyclooxygenase [COX] inhibitors: adjusted hazard ratio [HR] 1.10, 95% confidence interval [CI] 0.99-1.22; selective COX-2 inhibitors: adjusted HR 1.43, 95% CI 0.79-2.59). There was no increased risk for specific NSAID drugs, except for a significantly increased risk with exposure to indomethacin (adjusted HR 2.8, 95% CI 1.70-4.69). We found no dose-response effect.

INTERPRETATION

We found no increased risk of spontaneous abortion following exposure to NSAIDs. Further research is needed to assess the risk following exposure to selective COX-2 inhibitors.

Controversies in endocrinology: On the need for universal thyroid screening in pregnant women

There is a well-known controversy among scientific societies regarding the recommendation to screen for thyroid dysfunction (TD) during pregnancy. Although several studies have shown an association between maternal subclinical hypothyroidism and/or hypothyroxinemia with obstetric problems and/or neurocognitive impairment in the offspring, there is only limited evidence on the possible positive effects of thyroxine (T4) treatment in such cases. Despite the scarcity of this evidence, there is a widespread agreement among clinicians on the need for treatment of clinical hypothyroidism during pregnancy and the risks that could arise due to therapeutic abstention. As maternal TD is a quite prevalent condition, easily diagnosed and for which an effective and safe treatment is available, some scientific societies have proposed to assess thyroid function during the first trimester of pregnancy and ideally before week 10 of gestational age. Given the physiologic changes of thyroid function during pregnancy, hormone assessment should be performed using trimester-specific reference values ideally based on locally generated data as geographic variations have been detected. Screening of TD should be based on an initial determination of TSH performed early during the first trimester and only if abnormal should it be followed by either a free or total T4 measurement. Furthermore, adequate iodine supplementation during pregnancy is critical and if feasible it should be initiated before the woman attempts to conceive.

Therapy of endocrine disease: Impact of iodine supplementation in mild-to-moderate iodine deficiency: systematic review and meta-analysis

BACKGROUND

Although the detrimental effects of severe iodine deficiency are well recognised, the benefits of correcting mild-to-moderate iodine deficiency are uncertain.

OBJECTIVES

We undertook a systematic review of the impact of iodine supplementation in populations with mild-to-moderate iodine deficiency.

METHODS

We searched Medline and the Cochrane library for relevant articles published between January 1966 and April 2013, which investigated the effect of iodine supplementation on maternal and newborn thyroid function, infant neurodevelopment and cognitive performance in school-age children. The quality of studies was graded and eligible trials were evaluated in the meta-analysis.

RESULTS

Nine randomised controlled trials (RCTs) and eight observational studies met the inclusion criteria. Controlled trials on infant neurodevelopment were lacking; gestational iodine supplementation reduced maternal thyroid volume and serum thyroglobulin and in some studies prevented a rise in serum thyroid-stimulating hormone. None of the intervention trials recorded an excess frequency of thyroid dysfunction in contrast to observational studies. A pooled analysis of two RCTs which measured cognitive function in school-age children showed modest benefits of iodine supplementation on perceptual reasoning (standardised mean difference (SMD) 0.55; 95% CI 0.05, 1.04; P=0.03) and global cognitive index (SMD 0.27; 95% CI 0.10, 0.44; P=0.002) with significant heterogeneity between studies.

CONCLUSION

Iodine supplementation improves some maternal thyroid indices and may benefit aspects of cognitive function in school-age children, even in marginally iodine-deficient areas. Further large prospective controlled studies are urgently required to clarify these findings and quantify the risk/benefits of iodine supplementation in regions previously believed to be iodine sufficient such as the UK.

Pregnancy-induced alterations in mitochondrial function in euthyroid pregnant women and pregnant women with subclinical hypothyroidism; relation to adverse outcome

Background

It is well documented that overt hypothyroidism is associated with adverse pregnancy outcomes, but studies of subclinical hypothyroidism have demonstrated conflicting results.

Objective

Thyroid hormones are known to regulate mitochondrial function, and the aim of this study was to examine the possible relationship of subclinical hypothyroidism and mitochondrial dysfunction to adverse pregnancy outcomes in pregnant women.

Methods

Women in their third trimester of pregnancy (n = 113) who did not receive thyroid medication were included in this cross-sectional study. All participants were interviewed, and their thyroid status was determined. All participants had concentrations of thyroid hormones (fT₄ and tT₃) within the reference range. In addition to thyroid status, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were measured by flow cytometry. To establish a reference range of MMP and ROS, a group of euthyroid, nonpregnant women were used as euthyroid controls. Adverse pregnancy outcome was defined as preterm delivery, preeclampsia, placental abruption, Apgar score <7 points 1 minute after birth, or postpartum hemorrhage.

Results

The prevalence of subclinical hypothyroidism among pregnant women was 17% (n = 19), and the number of overall adverse pregnancy outcomes was increased (p = 0.02) compared with that in euthyroid pregnant women. Preeclampsia, poor Apgar score, and postpartum hemorrhage were more frequent in the subclinical hypothyroidism group than in the euthyroid group (p = 0.04, p = 0.001 and p = 0.03, respectively), and more women showed prolonged gestation and gave birth later than 41 weeks of gestation than in the euthyroid group (p = 0.04). Compared with euthyroid, nonpregnant controls, a physiological upregulation of mitochondrial function was observed in euthyroid pregnant women. This was impaired in pregnant women with subclinical hypothyroidism. Compared with euthyroid, nonpregnant controls, pregnant women had increased ROS regardless of their thyroid status.

Conclusion

We speculate that the unfavorable effects on mitochondrial function in women with subclinical hypothyroidism may be associated with higher prevalence of adverse pregnancy outcomes.

Thyroid disease during pregnancy: options for management

Thyroid diseases affect up to 5% of all pregnancies. Adverse pregnancy and neonatal outcomes are increased by maternal thyroid disease and adequate treatment is thought to reduce these risks. Hypothyroidism is commonly treated with levothyroxine, with pregnancy increasing levothyroxine requirements in most women treated for hypothyroidism. Hyperthyroidism is often treated with antithyroid drugs in pregnancy. However, they are not completely safe to use during pregnancy as methimazole increases risk of neonatal malformations and propylthiouracil increases risk of maternal hepatotoxicity. Propylthiouracil is recommended to be used during the first trimester and switch to methimazole is recommended thereafter to reduce risk of hepatotoxicity. The treatment goal for hypothyroidism and hyperthyroidism is to achieve euthyroidism quickly and maintain it throughout pregnancy. Autoimmune thyroiditis and isolated maternal hypothyroxinemia do not currently warrant treatment during pregnancy, unless hypothyroidism ensues. Treatment of thyroid nodules and differentiated thyroid cancer can generally be safely postponed until after delivery.

Hypothyroidism in pregnancy

Hypothyroidism is the most common pregnancy-related thyroid disorder, affecting 3-5% of all pregnant women. Subclinical hypothyroidism is more common than is overt hypothyroidism, and is usually defined as a serum thyroid-stimulating hormone (TSH) concentration greater than the pregnancy-specific reference range for each laboratory value, or by serum TSH concentrations greater than 2·5 mIU/L in the first trimester and greater than 3 mIU/L in the second and third trimesters. Some authors have defined subclinical hypothyroidism as a serum TSH between 5 and 10 mIU/L, and overt hypothyroidism as a serum TSH greater than 10 mIU/L, but this is not the commonly accepted definition. Once overt hypothyroidism is diagnosed, treatment with levothyroxine should be started to achieve serum TSH concentrations within the reference ranges for pregnancy as soon as possible. For patients with subclinical hypothyroidism, recommendations for therapy differ between various professional groups as a result of inconsistent data from both observational studies and clinical trials regarding the benefits for the mother or the child. Similarly, because benefits of therapy are still uncertain, universal screening of all pregnant women for subclinical hypothyroidism or thyroid autoimmunity is not recommended by most professional groups. During gestation, an increase in levothyroxine dose is required in more than 50% of women with previously diagnosed hypothyroidism, and can be managed by increasing the levothyroxine dose by 30% when pregnancy is confirmed.

Adequate levothyroxine doses for the treatment of hypothyroidism newly discovered during pregnancy

BACKGROUND

Recent guidelines recommend thyrotropin (TSH) target levels of ≤2.5 mIU/L for the first trimester and ≤3 mIU/L for the subsequent trimesters. Euthyroidism should be attained as soon as possible, but there are no precise indications about the initial levothyrorine (LT4) dose. The aim of our study was to determine the appropriate LT4 doses in order to normalize TSH levels in patients with newly discovered subclinical hypothyroidism (SCH) during pregnancy, and to correlate them with basal TSH levels. The adequate LT4 doses for women with SCH were also compared to those required in pregnant women with overt hypothyroidism (OH).

METHODS

Seventy-seven patients with newly diagnosed hypothyroidism during pregnancy were retrospectively analyzed. Patients were assigned to group 1 (n = 64) with SCH or group 2 (n = 13) with OH. SCH patients were subdivided into two groups: group 1a serum TSH >2.5 (1st trimester) or >3 (2nd or 3rd trimester) to 4.2 mIU/L; and group 1b TSH level > 4.21-10 mIU/L. All patients were treated with LT4 as soon as hypothyroidism was diagnosed. The dose that allowed a TSH of ≤2.5 mIU/L to be reached in the first trimester or one that allowed a TSH of ≤3 mIU/L to be reached during the second and third trimesters was considered the appropriate one.

RESULTS

A significant difference (p < 0.0001) in the appropriate LT4 dose (mean ± SD, μg/kg/day) was observed between group 1 and group 2: 1.31 ± 0.36 versus 2.33 ± 0.59. Patients in group 1a required a significantly lower LT4 dose (p < 0.014) than group1b: 1.20 ± 0.39 versus 1.42 ± 0.31 μg/kg/day. In 57 of the 64 (89.06%) women with SCH and in 10/13 (76.92%) women with OH, the appropriate LT4 dose coincided with the initial dose. Only 11% and 23% respectively required additional adjustments. Once the appropriate dose of LT4 was prescribed, the time at which euthyroidism (mean ± SD, weeks) was confirmed was similar in patients with SCH (6.06 ± 3.3) and OH (5.3 ± 1.8). There were no miscarriages or premature deliveries.

CONCLUSIONS

When hypothyroidism is newly discovered during pregnancy, we suggest initiating the treatment with the following LT4 doses: 1.20 μg/kg/day for SCH with TSH ≤ 4.2  mIU/L, 1.42 μg/kg/day with TSH > 4.2-10, and 2.33 μg/kg/day for OH. By taking this approach, patients will promptly attain the euthyroid state avoiding additional increments and, probably, obstetric risks.

Impaired outcome of controlled ovarian hyperstimulation in women with thyroid autoimmune disease

BACKGROUND

Controlled ovarian hyperstimulation (COH) is a crucial step of assisted reproductive technology (ART). Thyroid dysfunction and autoimmune thyroid disease (ATD) may negatively affect the outcome of ART, but the underlying mechanisms are still poorly understood. Our aim was to evaluate the respective role of ATD and thyroid function, as assessed by serum thyrotropin (TSH), on the early outcome of COH.

METHODS

In total, 262 (202 ATD-negative and 60 ATD-positive) euthyroid subfertile women underwent ART. Before COH, serum follicle-stimulating hormone (FSH), luteinizing hormone, and estradiol (E2) were measured at cycle day 3, and progesterone at cycle day 21. At oocyte pickup and at embryo transfer, we evaluated the performance of recombinant FSH (r-FSH), as assessed by serum E2 concentration/total administered r-FSH units (E2/r-FSH) ratio and by oocyte quality.

RESULTS

At both oocyte pickup and embryo transfer, the performance of r-FSH was significantly poorer in ATD-positive than in ATD-negative women. In the ATD-positive group, women with a TSH <2.5 mIU/L displayed a higher serum E2 concentration at oocyte pickup, a higher E2/r-FSH ratio, and a greater number of mature metaphase II oocytes than women with a TSH >2.5 mIU/L. When ATD-positive women were divided into quartiles according to their serum TSH level, both the ovarian response to r-FSH and the number of mature metaphase II oocytes significantly increased from the lowest to the highest quartiles of serum TSH concentration.

CONCLUSIONS

ATD has a negative effect on the early outcome of COH, but this negative influence may be avoided with adequate levothyroxine therapy aimed at keeping TSH <2.5 mU/L. Thyroid antibodies and serum TSH should be checked in any woman undergoing ART.

Optimal treatment of hypothyroidism associated with live birth in cases of previous recurrent placental abruption and stillbirth

OBJECTIVE

To examine the clinical management of and placentas from pregnant women with hypothyroidism and obstetric history of recurrent stillbirth in order to identify possible etiologic mechanisms.

METHODS

Two cases involving 26-year-old women with hypothyroidism and history of recurrent stillbirth are reported. Placentas from all of the women's pregnancies were compared in order to identify histologic similarities.

RESULTS

In both cases, multifocal hemorrhagic infarctions and abruptions were seen, indicating progressive uteroplacental ischemic damage leading to stillbirth. Thrombophilia, infection, and diabetes tests were all negative. With meticulous monitoring and normalization of thyroid function by end of first/early second trimester in subsequent pregnancies, there were live births and no evidence of infarction on placental histology.

CONCLUSION

The 2 reported cases raise the possibility of uteroplacental ischemia and placental abruption being mechanisms by which hypothyroidism can lead to stillbirth; they also highlight the potential of minimizing this risk via adequate levothyroxine treatment from early pregnancy.

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.

Pregnancy outcomes in women with severe hypothyroidism

OBJECTIVE

Hypothyroidism during pregnancy has been associated with adverse obstetrical outcomes. Most studies have focused on subjects with a mild or subclinical disorder. The aims of the present study were to determine the relative rate of severe thyroid dysfunction among pregnant women with hypothyroidism, identify related factors and analyse the impact on pregnancy outcomes.

DESIGN

A retrospective case series design was employed.

METHODS

The study group included 101 pregnant women (103 pregnancies) with an antenatal serum TSH level >20.0 mIU/l identified from the 2009-2010 computerised database of a health maintenance organisation. Data were collected from the medical records. Pregnancy outcomes were compared with those of a control group of 205 euthyroid pregnant women during the same period.

RESULTS

The study group accounted for 1.04% of all insured pregnant women with recorded hypothyroidism during the study period. Most cases had an autoimmune aetiology. All women were treated with levothyroxine (L-T₄) during pregnancy. Maximum serum TSH level measured was 20.11-150 mIU/l (median 32.95 mIU/l) and median serum TSH level 0.36-75.17 mIU/l (median 7.44 mIU/l). The mean duration of hypothyroidism during pregnancy was 21.2 ± 13.2 weeks (median 18.5 weeks); in 36 cases (34.9%), all TSH levels during pregnancy were elevated. Adverse pregnancy outcomes included abortions in 7.8% of the cases, premature deliveries in 2.9% and other complications in 14.6%, with no statistically significant differences from the control group. Median serum TSH level during pregnancy was positively correlated with the rate of abortions+premature deliveries and rate of all pregnancy-related complications (P<0.05).

CONCLUSIONS

Abortions and premature deliveries occur infrequently in women with severe hypothyroidism. Intense follow-up and L-T₄ treatment may improve pregnancy outcomes even when target TSH levels are not reached.

Screening for overt thyroid disease in early pregnancy may be preferable to searching for small aberrations in thyroid function tests

Thyroid hormones are important regulators of foetal development, and in recent years, there has been much focus on the screening and treatment of pregnant women for even small aberrations in thyroid function tests. We searched PubMed for publications on thyroid function and pregnancy outcomes including child cognition, and included references from the retrieved articles. Both small aberrations in thyroid function tests in early pregnancy and an increase in risk of pregnancy complications may be caused by a functional change in the uteroplacental unit. Thus, the association found in several studies between small thyroid test abnormalities and pregnancy complications may be due to confounding, and thyroid hormone therapy will have no effect. On the other hand, screening of thyroid function in early pregnancy may identify 200-300 women with undiagnosed overt hypothyroidism per 100,000 pregnancies, which is at least five times more than the number of hypothyroid newborns identified by screening. A number of studies indicate that untreated overt thyroid disease in pregnancy may lead to complications. The potential benefit of screening and early therapy is supported by evidence, indicating that even severe maternal hypothyroidism does not lead to neurocognitive deficiencies in the child, if the condition is detected and treated during the first half of pregnancy. Screening and therapy for overt thyroid dysfunction in early pregnancy may be indicated, rather than focusing on identifying and treating small aberrations in thyroid function tests.

Thyroid stimulating hormone levels rise after assisted reproductive technology

PURPOSE

The goal of this study was to determine whether high E2 levels after controlled ovarian hyperstimulation affect TSH.

METHODS

Patients completing ART cycles between April-October 2010 were eligible for this cohort study. 180 patients were recruited however those with known thyroid disease were excluded. The final analysis included 154 subjects. Blood was collected at each visit during the ART cycle as well as at the pregnancy test. Samples were frozen at -20 °C and analyzed together for E2 and TSH using the same assay kit once all patients had completed their cycles. All participants were treated at the McGill University Health Center. A paired t-test was used to study the difference in TSH levels recorded at maximal and minimal Estradiol levels during ovarian stimulation. Multiple regression analysis was then used to determine if factors such as anti-thyroid antibodies and ovarian reserve measures affect this change in TSH. We used multiple imputation methods to account for missing data.

RESULTS

As E2 levels rose from low to supra-physiologic levels during treatment, TSH levels also rose significantly. This increase was clinically significant by the time of pregnancy test. The factors that potentially affected the change in TSH were: male factor/tubal factor infertility, type of protocol used as well as the presence of thyroid antibodies.

CONCLUSIONS

Although TSH increases during ART, this change only becomes clinically significant on the day of pregnancy test. Future studies should examine TSH changes specifically in certain "at-risk" sub-groups such as those with antibodies and known thyroid disease.

Impact of subclinical hypothyroidism in women with recurrent early pregnancy loss

OBJECTIVE

To assess the impact of subclinical hypothyroidism (SCH) in women with recurrent early pregnancy loss (REPL).

DESIGN

Observational cohort study.

SETTING

REPL program in an academic medical center.

PATIENT(S)

286 women with a history of ≥2 pregnancy losses <10 weeks.

INTERVENTION(S)

From 2004-2007, no treatment for women with SCH (thyroid-stimulating hormone [TSH] >2.5 mIU/L with a normal free thyroxine or free thyroxine index); from 2008 onward, levothyroxine treatment prepregnancy to maintain TSH ≤2.5 mIU/L.

MAIN OUTCOME MEASURE(S)

Live-birth rate (LBR).

RESULT(S)

The prevalence of SCH was 55 (19%) of 286 in this REPL cohort. The cumulative LBR was 27 (69%) of 39 for women with SCH versus 104 (74%) of 141 for euthyroid women. The per-pregnancy LBR was 34 (49%) of 69 for SCH versus 129 (58%) of 221 for euthyroid women. When the LBR was compared between treated and untreated SCH, the cumulative LBR was 17 (71%) of 24 versus 10 (67%) of 15, respectively. The per-pregnancy LBR for SCH treated versus untreated women was 22 (48%) of 46 versus 12 (52%) of 23, respectively.

CONCLUSION(S)

Although there was a high prevalence of SCH in the REPL cohort, there was no statistically significant difference in the subsequent live-birth rate when comparing women with SCH and euthyroid women, or treated and untreated SCH.

[Reference values and variability study of thyroid hormones in pregnant women from El Bierzo]

BACKGROUND AND OBJECTIVES

El Bierzo area is characterized by low urinary iodine levels in the pregnant population. Guidelines recommend that local reference values are established for the diagnosis of thyroid dysfunction in pregnancy. Our objectives were to establish reference values for thyroid-stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyronine (FT3) in women in the first trimester of pregnancy and to explore the factors influencing variability in these hormones.

PATIENTS AND METHODS

A retrospective study of 412 women in the first trimester of pregnancy who were measured serum levels of TSH, FT4, and FT3; 163 women with conditions with a potential influence on thyroid function were excluded. Thirty smoking pregnant women were also excluded from the study of reference values. Factors examined in the variability study included age, body mass index (BMI), and smoking. A multifactorial analysis of covariance was performed.

RESULTS

Reference values in first-trimester pregnant women were: TSH: 0.497-3.595 mIU/L; FT4: 0.90-1.42 ng/dL; FT3: 2.49-3.56 pg/mL. TSH levels depended on mother age and on interaction between age and smoking. FT3 levels depended on the mother's BMI and smoking, and there was also an interaction between both factors.

CONCLUSION

The reference values found may be used to assess thyroid dysfunction in pregnant women from El Bierzo. TSH and FT3 levels are influenced by age and BMI of the mother and by smoking, in addition to the interaction of these factors.

Thyroid testing and management of hypothyroidism during pregnancy: a population-based study

CONTEXT

There are international guidelines on thyroid function testing and management of hypothyroidism during pregnancy. Few studies have evaluated how they are implemented into clinical practice.

OBJECTIVE

In this descriptive study, we assessed the implementation of international guidelines in this field into local guidelines and also into clinical practice.

DESIGN AND PARTICIPANTS

In a nationwide survey, all guidelines in Sweden were collected (n = 29), and the adherence of the local guidelines to The Endocrine Society Guidelines 2007 was evaluated. In a follow-up in 1 district, 5254 pregnant women with an estimated date of delivery between January 1, 2009, and December 31, 2011, were included for subsequent review of their medical reports.

RESULTS

All but 1 district had guidelines on the subject. All local guidelines included fewer than the 10 listed reasons for thyroid testing recommended by The Endocrine Society Guidelines. Furthermore, most guidelines recommended additional types of thyroid function tests to TSH sampling and lower trimester-specific TSH upper reference limits for women on levothyroxine treatment (P < .001). In the follow-up, the thyroid testing rate was 20%, with an overall frequency of women with trimester-specific elevated TSH of 18.5%. More than half of the women (50.9%) who were on levothyroxine treatment at conception had an elevated TSH level at thyroid testing according to The Endocrine Society Guidelines.

CONCLUSIONS

The local guidelines are variable and poorly compliant with international guidelines. Performance of thyroid testing is not optimal, and rates of elevated TSH at testing are extremely high in subgroups.

Thyroid diseases and adverse pregnancy outcomes in a contemporary US cohort

CONTEXT

Thyroid diseases are inconsistently reported to increase risk for pregnancy complications.

OBJECTIVE

The objective of this study was to study pregnancy complications associated with common and uncommon thyroid diseases.

DESIGN, SETTING, AND PARTICIPANTS

We analyzed singleton pregnancies (N = 223 512) from a retrospective US cohort, the Consortium on Safe Labor (2002-2008). Thyroid diseases and outcomes were derived from electronic medical records. Multivariable logistic regression with generalized estimating equations estimated adjusted odds ratios (ORs) with 99% confidence intervals (99% CI).

MAIN OUTCOME MEASURES

Hypertensive diseases, diabetes, preterm birth, cesarean sections, inductions, and intensive care unit (ICU) admissions were analyzed.

RESULTS

Primary hypothyroidism was associated with increased odds of preeclampsia (OR = 1.47, 99% CI = 1.20-1.81), superimposed preeclampsia (OR = 2.25, 99% CI = 1.53-3.29), gestational diabetes (OR = 1.57, 99% CI = 1.33-1.86), preterm birth (OR = 1.34, 99% CI = 1.17-1.53), induction (OR = 1.15, 99% CI = 1.04-1.28), cesarean section (prelabor, OR = 1.31, 99% CI = 1.11-1.54; after spontaneous labor OR = 1.38, 99% CI = 1.14-1.66), and ICU admission (OR = 2.08, 99% CI = 1.04-4.15). Iatrogenic hypothyroidism was associated with increased odds of placental abruption (OR = 2.89, 99% CI = 1.14-7.36), breech presentation (OR = 2.09, 99% CI = 1.07-4.07), and cesarean section after spontaneous labor (OR = 2.05, 99% CI = 1.01-4.16). Hyperthyroidism was associated with increased odds of preeclampsia (OR = 1.78, 99% CI = 1.08-2.94), superimposed preeclampsia (OR = 3.64, 99% CI = 1.82-7.29), preterm birth (OR = 1.81, 99% CI = 1.32-2.49), induction (OR = 1.40, 99% CI = 1.06-1.86), and ICU admission (OR = 3.70, 99% CI = 1.16-11.80).

CONCLUSIONS

Thyroid diseases were associated with obstetrical, labor, and delivery complications. Although we lacked information on treatment during pregnancy, these nationwide data suggest either that there is a need for better thyroid disease management during pregnancy or that there may be an intrinsic aspect of thyroid disease that causes poor pregnancy outcomes.

Monocarboxylate transporter 8 modulates the viability and invasive capacity of human placental cells and fetoplacental growth in mice

Monocarboxylate transporter 8 (MCT8) is a well-established thyroid hormone (TH) transporter. In humans, MCT8 mutations result in changes in circulating TH concentrations and X-linked severe global neurodevelopmental delay. MCT8 is expressed in the human placenta throughout gestation, with increased expression in trophoblast cells from growth-restricted pregnancies. We postulate that MCT8 plays an important role in placental development and transplacental TH transport. We investigated the effect of altering MCT8 expression in human trophoblast in vitro and in a Mct8 knockout mouse model. Silencing of endogenous MCT8 reduced T3 uptake into human extravillous trophoblast-like cells (SGHPL-4; 40%, P<0.05) and primary cytotrophoblast (15%, P<0.05). MCT8 over-expression transiently increased T3 uptake (SGHPL-4∶30%, P<0.05; cytotrophoblast: 15%, P<0.05). Silencing MCT8 did not significantly affect SGHPL-4 invasion, but with MCT8 over-expression T3 treatment promoted invasion compared with no T3 (3.3-fold; P<0.05). Furthermore, MCT8 silencing increased cytotrophoblast viability (∼20%, P<0.05) and MCT8 over-expression reduced cytotrophoblast viability independently of T3 (∼20%, P<0.05). In vivo, Mct8 knockout reduced fetal:placental weight ratios compared with wild-type controls at gestational day 18 (25%, P<0.05) but absolute fetal and placental weights were not significantly different. The volume fraction of the labyrinthine zone of the placenta, which facilitates maternal-fetal exchange, was reduced in Mct8 knockout placentae (10%, P<0.05). However, there was no effect on mouse placental cell proliferation in vivo. We conclude that MCT8 makes a significant contribution to T3 uptake into human trophoblast cells and has a role in modulating human trophoblast cell invasion and viability. In mice, Mct8 knockout has subtle effects upon fetoplacental growth and does not significantly affect placental cell viability probably due to compensatory mechanisms in vivo.

High prevalence of thyroid dysfunction in pregnant women

BACKGROUND/AIM

Maternal thyroid dysfunction during pregnancy has been associated with adverse obstetric and neonatal outcomes. This prospective study evaluates the prevalence of these disorders in pregnant women.

SUBJECTS AND METHODS

Serum levels of TSH, free T4 (fT4), and thyroperoxidase antibodies (TPO-Ab) were measured in 951 women at different gestational ages of pregnancy. Trimester-specific reference ranges for TSH were used to classify pregnant women into five groups: 1) Overt hypothyroidism (OH); 2) Subclinical hypothyroidism (SCH); 3) Isolated hypothyroxinemia (IH); 4) Low TSH (isolated or associated with high fT4); and 5) Normal. A classification was made also according to the lower and upper ranges provided by the manufacturer for thyroid hormones. Pregnant women who were at a high risk of developing thyroid disease were identified.

RESULTS

Altogether, 117 women (12.3%) had hypothyroidism and 25 (2.6%) had low TSH. The prevalence of both OH and SCH was higher in the high-risk group than in the low-risk group, but 17.9% of women with hypothyroidism were classified at low-risk. A family history of thyroid disorders and TPO-Ab positivity increased the risk of SCH. Using non-pregnant reference range for TSH, 10.6% of women were misclassificated.

CONCLUSIONS

The high prevalence of hypothyroidism observed in this study suggests that accurate thyroid screening with trimester specific reference ranges should be warranted, particularly in areas with mild to moderate iodine deficiencies.

Interventions for clinical and subclinical hypothyroidism pre-pregnancy and during pregnancy

BACKGROUND

Over the last decade there has been enhanced awareness of the appreciable morbidity of thyroid dysfunction, particularly thyroid deficiency. Since treating clinical and subclinical hypothyroidism may reduce adverse obstetric outcomes, it is crucial to identify which interventions are safe and effective.

OBJECTIVES

To identify interventions used in the management of hypothyroidism and subclinical hypothyroidism pre-pregnancy or during pregnancy and to ascertain the impact of these interventions on important maternal, fetal, neonatal and childhood outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 March 2013).

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-randomised controlled trials that compared a pharmacological intervention for hypothyroidism and subclinical hypothyroidism pre-pregnancy or during pregnancy with another intervention or placebo.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trial eligibility and quality and extracted the data.

MAIN RESULTS

We included four RCTs of moderate risk of bias involving 362 women. In one trial of 115 women, levothyroxine therapy to treat pregnant euthyroid (normal thyroid function) women with thyroid peroxidase antibodies was not shown to reduce pre-eclampsia significantly (risk ratio (RR) 0.61; 95% confidence interval (CI) 0.11 to 3.48) but did significantly reduce preterm birth by 72% (RR 0.28; 95% CI 0.10 to 0.80). Two trials of 30 and 48 hypothyroid women respectively compared levothyroxine doses, but both trials reported only biochemical outcomes. A trial of 169 women compared the trace element selenomethionine (selenium) with placebo and no significant differences were seen for either pre-eclampsia (RR 1.44; 95% CI 0.25 to 8.38) or preterm birth (RR 0.96; 95% CI 0.20 to 4.61). None of the four trials reported on childhood neurodevelopmental delay.There was a non-significant trend towards fewer miscarriages with levothyroxine, and selenium showed some favourable impact on postpartum thyroid function and a decreased incidence of moderate to advanced postpartum thyroiditis.

AUTHORS' CONCLUSIONS

This review found no difference between levothyroxine therapy and a control for treating pregnant euthyroid women with thyroid peroxidase antibodies for the outcome of pre-eclampsia, however a reduction in preterm birth and a trend towards reduced miscarriage with levothyroxine was shown. This review also showed no difference for pre-eclampsia or preterm birth when selenium was compared with placebo, however a promising reduction in postpartum thyroiditis was shown. Childhood neurodevelopmental delay was not assessed by any trial included in the review.Given that this review is based on four trials of moderate risk of bias, with only two trials contributing data (n = 284), there is insufficient evidence to recommend the use of one intervention for clinical or subclinical hypothyroidism pre-pregnancy or during pregnancy over another, for improving maternal, fetal, neonatal and childhood outcomes.

Screening for maternal thyroid dysfunction in pregnancy: a review of the clinical evidence and current guidelines

Observational studies have demonstrated that maternal thyroid dysfunction and thyroid autoimmunity in pregnancy may be associated with adverse obstetric and fetal outcomes. Treatment of overt maternal hyperthyroidism and overt hypothyroidism clearly improves outcomes. To date there is limited evidence that levothyroxine treatment of pregnant women with subclinical hypothyroidism, isolated hypothyroxinemia, or thyroid autoimmunity is beneficial. Therefore, there is ongoing debate regarding the need for universal screening for thyroid dysfunction during pregnancy. Current guidelines differ; some recommend an aggressive case-finding approach, whereas others advocate testing only symptomatic women or those with a personal history of thyroid disease or other associated medical conditions.

The Use of TSH in Determining Thyroid Disease: How Does It Impact the Practice of Medicine in Pregnancy?

During the last four decades, there have been considerable advances in the efficacy and precision of serum thyroid function testing. The development of the third generation assays for the measurement of serum thyroid stimulating hormone (TSH, thyrotropin) and the log-linear relationship with free thyroxine (T4) established TSH as the hallmark of thyroid function testing. While it is widely accepted that TSH outside of the normal range is consistent with thyroid dysfunction, a vast multitude of additional factors must be considered before an accurate clinical diagnosis can be made. This is especially important during pregnancy, when the thyroid is under considerable additional pregnancy-related demands requiring significant maternal physiological changes. This paper examines serum TSH measurement in pregnancy and some associated potential confounding factors.

Increased thyroid autoimmunity among women with multiple sclerosis in the postpartum setting

Background:

Multiple sclerosis (MS) patients are predisposed to thyroid abnormalities, but the risk for pregnancy-related thyroid pathology among MS patients has not been evaluated.

Objectives:

The objectives of this research are to prospectively evaluate the prevalence of thyroid autoimmunity among MS patients in relation to pregnancy, and to investigate its impact on pregnancy outcome, postpartum depression and fatigue.

Methods:

Forty-six pregnant MS patients underwent repeat testing for serum thyroid antibodies (Abs), clinical evaluation and thyroid hormone measurement. Results were compared to 35 age-matched healthy mothers.

Results:

At six months postpartum 35.3% of MS patients presented elevated levels of thyroid Abs compared to 5.7% of controls, p = 0.01. Mean thyroid Ab concentrations among MS patients were significantly reduced during pregnancy and returned to maximal levels at six months postpartum. The proportion of individuals with postpartum thyroid dysfunction did not differ significantly between MS patients and healthy controls (3.4% vs 2.9%, p = 1.00). Elevated thyroid Ab levels did not increase the risk for adverse pregnancy outcome, fatigue or postpartum depression.

Conclusions:

Considering the tendency of MS mothers to develop thyroid autoimmunity postpartum and in association to treatments, we recommend screening MS patients for thyroid dysfunction (TSH) during early pregnancy and after delivery.

Hypothyroidism and diabetes mellitus - a risky dual gestational endocrinopathy

Objectives. Diabetes mellitus (DM) and hypothyroidism are each associated with increased rate of pregnancy complications. However, their combined morbidity during gestation is poorly studied. Therefore, the aims of this study were to determine the prevalence of the combined morbidity of DM & hypothyroidism and whether it is associated with adverse maternal and neonatal outcome.

Study design. This population based retrospective cohort study included 87,213 women who had 232,293 deliveries. All deliveries were divided into the following groups: (1) hypothyroidism & DM (n = 171); (2) hypothyroidism (n = 1502); (3) DM (n = 13,324); and (4) deliveries of women with neither endocrinopathy, who served as a control group (n = 217, 296).

Results. The prevalence of DM & hypothyroidism in our population was 0.17%. In comparisons to the other study groups, women with DM & hypothyroidism had higher rates of infertility (p < 0.001), preeclampsia (p < 0.001), chronic hypertension (p < 0.001), preterm birth (p < 0.001), and cesarean deliveries (p < 0.001). In Generalized Estimating Equations (GEE) model, hypothyroidism & DM was an independent risk factor for cesarean section (OR 3.46; 95% CI 2.53–4.75) and for preeclampsia (OR 1.82; 95%CI 1.16–2.84).

Conclusion. The combination of DM & hypothyroidism is rare, yet it is associated with higher rate of infertility, cesarean sections, preterm deliveries, and hypertensive disorders of pregnancy than the rest of the population. This dual endocrinological combination is an independent risk factor for preeclampsia and cesarean section. These findings suggest that these patients are at risk for perinatal complications and should be followed and delivered as high risk pregnancies.

Pregnancy outcomes with thyroxine replacement for subclinical hypothyroidism: Role of thyroid autoimmunity

OBJECTIVE

To study pregnancy outcomes in relation to thyroid peroxidase antibody (TPOAb) status with optimum thyroxine replacement for subclinical hypothyroidism.

MATERIALS AND METHODS

Ninety-eight women with subclinical hypothyroidism were followed up until the end of their pregnancy. TPO antibody status was performed for 59 women (positive 20, negative 39). Levothyroxine was supplemented to maintain TSH between 0.3-3 mIU/l in all patients, irrespective of TPOAb status. Pregnancy outcomes were noted as pregnancy-induced hypertension (PIH), antepartum or postpartum hemorrhage, preterm delivery, and spontaneous abortion. Outcomes were compared between 3 groups as per TPO antibody status (positive, negative, and undetermined), which were matched for age and gestational period.

RESULTS

Thyroid autoimmunity was noted in 34% of women screened for TPO antibody. A total of 11 adverse pregnancy outcomes were recorded (4 spontaneous abortions, 4 preterm deliveries, 3 PIH) with no significant difference between the groups.

CONCLUSION

Adverse pregnancy outcomes were not different in the 3 groups with adequate thyroxine replacement for pregnant women with subclinical hypothyroidism targeting TSH in euthyroid range, irrespective of thyroid autoimmunity status.

Reduction of miscarriages through universal screening and treatment of thyroid autoimmune diseases

BACKGROUND/AIMS

Universal screening for thyroid diseases during pregnancy is controversial. Targeted screening does not identify all women with thyroid dysfunction. Furthermore, antithyroid peroxidase antibodies (TPOAb) are suspected to be associated with an increased risk of fetal loss, premature delivery and hypothyroidism. The aim of our study was to assess the rationale behind universal screening and propose thyroxine treatment in particular cases.

METHODS

Between January 2008 and May 2009, 537 consecutive iodine-supplemented women with a singleton pregnancy [441 TPOAb- controls and 96 TPOAb+ women (47 nontreated and 49 treated)] were evaluated using thyroid and obstetric parameters. According to our algorithm for thyroid screening in pregnancy, if thyroid-stimulating hormone (TSH) exceeded 1 mU/l in TPOAb+ women, 50 µg of levothyroxine (L-T4) was prescribed.

RESULTS

The miscarriage rate was significantly higher in the nontreated TPOAb+ group compared with the treated group (16 vs. 0%; p = 0.02). Compared to the control group, TSH in TPOAb+ patients was higher at the first prenatal visit prior to L-T4 treatment (p < 0.01), while free thyroxine was higher than in the control group after the 20th week (p < 0.05).

CONCLUSIONS

Our study supports the potential benefit of universal screening and L-T4 treatment for autoimmune thyroid disease during pregnancy. Efforts are still needed to further decrease miscarriage rates.

Dichlorodiphenyltrichloroethane (DDT), DDT metabolites and pregnancy outcomes

Organochlorine pesticides (OCPs) are persistent endocrine disruptors. OCPs cross the placenta; this prenatal exposure has been associated with adverse pregnancy outcomes. We investigated associations between prenatal exposure to OCPs and gestational age and birth weight in 600 infants born between 1960 and 1963. The primary OCP was 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (p,p'-DDT), its primary metabolite, 1,1'-dichloro-2,2'-bis(p-chlorophenyl)ethylene (p,p'-DDE) and the contaminant, 1,1,1-trichloro-2-(p-chlorophenyl)-2-(o-chlorophenyl)-ethane (o,p'-DDT). Regression analysis indicated that for each natural log unit increase in p,p'-DDT, birth weight increased by 274 g (95% CI: 122, 425) when controlling for p,p'-DDE and o,p'-DDT. At a given level of p,p'-DDT exposure, o,p'-DDT and p,p'-DDE were associated with decreased birth weight. p,p'-DDE was negatively associated with length of gestation, controlling for p,p'-DDT and o,p'-DDT. These findings suggest opposing associations between exposure to p,p'-DDT and p,p'-DDE and birth weight. We did not find evidence to support mediation by maternal thyroid hormone status nor that the association differed by sex.

[Detection of thyroid dysfunction in pregnant women: universal screening is justified]

There is a controversy among different scientific societies in relation to the recommendations on whether universal screening for the detection of thyroid dysfunction during gestation should be performed or not. Although various studies have shown an association between subclinical hypothyroidism or hypothyroxinemia with obstetric problems and/or neurocognitive impairment in the offspring, no evidence on the possible positive effects of treatment of such conditions with thyroxin has been demonstrated so far. However, there is a general agreement about the need for treatment of clinical hypothyroidism during pregnancy and the risks of not doing so. Because it is a common, easily diagnosed and effectively treated disorder without special risk, the working Group of Iodine Deficiency Disorders and Thyroid Dysfunction of the Spanish Society of Endocrinology and Nutrition and Spanish Society of Gynaecology and Obstetrics recommends an early evaluation (before week 10) of thyroid function in all pregnant women. Given the complex physiology of thyroid function during pregnancy, hormone assessment should be performed according to reference values for each gestational trimester and generated locally in each reference laboratory. Thyrotropin determination would be sufficient for screening purposes and only if it is altered, free thyroxin or total thyroxin would be required. Adequate iodine nutrition is also highly recommended before and during pregnancy to contribute to a normal thyroid function in the pregnant women and fetus.

Management of thyroid dysfunction during pregnancy and postpartum: an Endocrine Society clinical practice guideline

OBJECTIVE

The aim was to update the guidelines for the management of thyroid dysfunction during pregnancy and postpartum published previously in 2007. A summary of changes between the 2007 and 2012 version is identified in the Supplemental Data (published on The Endocrine Society's Journals Online web site at http://jcem.endojournals.org).

EVIDENCE

This evidence-based guideline was developed according to the U.S. Preventive Service Task Force, grading items level A, B, C, D, or I, on the basis of the strength of evidence and magnitude of net benefit (benefits minus harms) as well as the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence.

CONSENSUS PROCESS

The guideline was developed through a series of e-mails, conference calls, and one face-to-face meeting. An initial draft was prepared by the Task Force, with the help of a medical writer, and reviewed and commented on by members of The Endocrine Society, Asia and Oceania Thyroid Association, and the Latin American Thyroid Society. A second draft was reviewed and approved by The Endocrine Society Council. At each stage of review, the Task Force received written comments and incorporated substantive changes.

CONCLUSIONS

Practice guidelines are presented for diagnosis and treatment of patients with thyroid-related medical issues just before and during pregnancy and in the postpartum interval. These include evidence-based approaches to assessing the cause of the condition, treating it, and managing hypothyroidism, hyperthyroidism, gestational hyperthyroidism, thyroid autoimmunity, thyroid tumors, iodine nutrition, postpartum thyroiditis, and screening for thyroid disease. Indications and side effects of therapeutic agents used in treatment are also presented.

Evaluation and treatment of recurrent pregnancy loss: a committee opinion

The majority of miscarriages are sporadic and most result from genetic causes that are greatly influenced by maternal age. Recurrent pregnancy loss (RPL) is defined by two or more failed clinical pregnancies, and up to 50% of cases of RPL will not have a clearly defined etiology.

Subclinical thyroid disease and the incidence of hypertension in pregnancy

OBJECTIVE

To estimate the possibility of long-term effects of subclinical thyroid dysfunction on hypertension and other cardiovascular-related conditions during pregnancy.

METHODS

This is a secondary analysis of a prospective prenatal population-based study in which serum thyroid-function analytes were measured from November 2000 through April 2003. Women with evidence of overt thyroid disease were excluded. The remaining women were classified as being euthyroid, having subclinical hyperthyroid, or having subclinical hypothyroid, and the frequency of pregnancy-associated hypertensive disorders was compared between these groups.

RESULTS

Pregnancy outcomes in 24,883 women were analyzed for pregnancy hypertension, classified as gestational hypertension, mild preeclampsia, or severe preeclampsia. The incidence of hypertensive disorders were compared between the three cohorts. The overall incidences of hypertension in pregnancy were 6.2%, 8.5%, and 10.9% in the subclinical hyperthyroid, euthyroid, and subclinical hypothyroid groups, respectively, and were found to be significant when unadjusted (P=.016). After adjusting for confounding factors, there was a significant association between subclinical hypothyroidism and severe preeclampsia (adjusted odds ratio 1.6, 95% confidence interval 1.1-2.4; P=.03).

CONCLUSION

Women with subclinical hypothyroidism identified during pregnancy have an increased risk for severe preeclampsia when compared with euthyroid women.

LEVEL OF EVIDENCE

II.

Thyroid function in pregnancy

Iodine is required for the production of thyroid hormones. Normal thyroid function during pregnancy is important for both the mother and developing fetus. This review discusses the changes in thyroid physiology that occur during pregnancy, the significance of thyroid function tests and thyroid antibody titers assessed during pregnancy, and the potential obstetric complications associated with maternal hypothyroidism.

In vitro fertilization pregnancy rates in levothyroxine-treated women with hypothyroidism compared to women without thyroid dysfunction disorders

BACKGROUND

Untreated hypothyroidism can lead to ovulatory dysfunction resulting in oligo-amenorrhea. Treatment with levothyroxine can reverse such dysfunction and thus should improve fertility. The purpose of this retrospective study was to assess whether in vitro fertilization (IVF) pregnancy rates differ in levothyroxine-treated women with hypothyroidism compared to women without thyroid dysfunction/disorders.

METHODS

Treated hypothyroid and euthyroid women undergoing IVF at an academic IVF center were studied after Institutional Review Board approval. Women with hypothyroidism were treated with levothyroxine 0.025-0.15 mg/day for at least 3 months to maintain baseline thyrotropin (TSH) levels of 0.35-4.0 μU/mL prior to commencing IVF treatment (HYPO-Rx group). Causes of infertility were similar in both groups with the exception of male factor, which was more common in the HYPO-Rx group. The main outcomes studied were implantation rate, clinical pregnancy rate, clinical miscarriage rate, and live birth rate.

RESULTS

We reviewed the first IVF retrieval cycle performed on 240 women aged 37 years or less during the period January 2003 to December 2007. Women with treated hypothyroidism (n=21) had significantly less implantation, clinical pregnancy, and live birth rates than euthyroid women (n=219).

CONCLUSIONS

We conclude that, despite levothyroxine treatment, women with hypothyroidism have a significantly decreased chance of achieving a pregnancy following IVF compared to euthyroid patients. A larger prospective study is necessary to assess confounding variables, confirm these findings, and determine the optimal level of TSH prior to and during controlled ovarian hyperstimulation for IVF.

Thyroid peroxidase antibody in women with unexplained recurrent miscarriage: prevalence, prognostic value, and response to empirical thyroxine therapy

OBJECTIVE

To determine the prevalence, prognostic value, and response to thyroxine therapy of thyroid peroxidase antibody (TPOAb) in women with unexplained recurrent miscarriage (RM).

DESIGN

Observational, cohort study. The index cases included women with unexplained RM who tested positive for thyroid peroxidase antibody, and control cases included women with unexplained RM who tested negative for the antibodies; a second age-matched control group included women with RM who had a known cause for the repeated pregnancy loss.

SETTING

Tertiary referral center for RM.

PATIENT(S)

A total of 496 women with unexplained RM and 220 women with known diagnoses of RM who had a TPOAb test.

INTERVENTION(S)

Thyroxine replacement (50 μg daily during pregnancy) was begun in some patients who tested positive for thyroid peroxidase antibody, irrespective of TSH level.

MAIN OUTCOME MEASURE(S)

Miscarriage and live birth rates of a subsequent pregnancy.

RESULT(S)

A total of 496 women with unexplained RM who had a TPOAb test were included in the study. Of these, 10.7% of subjects tested positive for TPOAb. The prevalence of TPOAb in control subjects who had a known cause for RM was 11.8%. The live birth rate of the first pregnancies after referral was 64%, 53%, and 58% in TPOAb-negative, TPOAb-positive with thyroxine treatment, and TPOAb-positive without treatment subjects; there was no significant difference in the outcome between any two or three groups, or between those who tested positive or negative for TPOAb. Among women who tested positive for TPOAb, there was no difference in the antibody titer between women with unexplained RM and those with a known cause for the pregnancy loss. Women who tested positive for TPOAb were significantly more likely to have TSH levels above the normal range (≥4.2 mIU/L).

CONCLUSION(S)

The prevalence of TPOAb-positive results in women with unexplained RM is not higher than in the general population, TPOAb-positive status does not have a prognostic value regarding the outcome of a subsequent pregnancy, and empirical thyroxine therapy in those who tested positive did not seem to improve outcome.

Hypothyroidism in pregnancy

Pregnancy is a period that places great physiological stress on both the mother and the fetus. When pregnancy is compounded by endocrine disorders such as hypothyroidism, the potential for maternal and fetal adverse outcomes can be immense. While a lot of attention has been focused on the adverse fetal outcomes consequent to hypothyroidism, attention is also being gradually directed towards the adverse maternal outcomes of this disorder. Role of antibody positivity in influencing outcomes in a euthyroid woman, also needs further clarification. Prompt diagnosis and treatment of hypothyroidism in pregnancy is very essential. Subclinical hypothyroidism also needs to be detected and treated to prevent adverse outcomes, especially maternal. Since women with hypothyroidism during pregnancy, especially of the autoimmune variety might have a flare up of the disorder post-partum, or might continue to require thyroxine replacement post-partum, adequate follow-up is mandatory. While targeted case finding is generally practised, recent evidence seems to indicate that universal screening might be a better option. In conclusion, routine screening, early confirmation of diagnosis and prompt treatment. Allied with regular post-partum follow up, is required to ensure favourable maternal and fetal outcomes.

Subclinical thyroid disease

Subclinical thyroid diseases--subclinical hyperthyroidism and subclinical hypothyroidism--are common clinical entities that encompass mild degrees of thyroid dysfunction. The clinical significance of mild thyroid overactivity and underactivity is uncertain, which has led to controversy over the appropriateness of diagnostic testing and possible treatment. In this Seminar, we discuss the definition, epidemiology, differential diagnoses, risks of progression to overt thyroid disease, potential effects on various health outcomes, and management of subclinical hyperthyroidism and subclinical hypothyroidism. Treatment recommendations are based on the degree to which thyroid-stimulating hormone concentrations have deviated from normal and underlying comorbidities. Large-scale randomised trials are urgently needed to inform how to best care for individuals with subclinical thyroid disease.

Treatment of thyroid disorders before conception and in early pregnancy: a systematic review

BACKGROUND

Thyroid disorders are associated with pregnancy complications. Universal screening is currently not recommended because of a lack of evidence on the effectiveness of treatment. Women with hyperthyroidism and hypothyroidism evidently require treatment but this is less clear for women with subclinical hypothyroidism and thyroid autoimmunity. Therefore, we conducted a systematic review to provide a comprehensive overview on the available treatment interventions.

METHODS

Relevant studies were identified by searching Medline, EMBASE and Cochrane Controlled Trials Register, published until December 2011.

RESULTS

From a total of 7334 primary selected titles, 22 articles were included for the systematic review and 11 were appropriate for meta-analyses. Eight studies reported on hyperthyroidism. Propylthiouracil (PTU) and methimazole reduce the risk for preterm delivery [risk ratio (RR): 0.23, confidence interval (CI): 0.1-0.52], pre-eclampsia (RR: 0.23, CI: 0.06-0.89) and low birthweight (RR: 0.38, CI: 0.22-0.66). The nine studies that reported on clinical hypothyroidism showed that levothyroxine is effective in reducing the risk for miscarriage (RR: 0.19, CI: 0.08-0.39) and preterm delivery (RR: 0.41, CI: 0.24-0.68). For treatment of subclinical hypothyroidism, current evidence is insufficient. The five studies available on thyroid autoimmunity showed a not significant reduction in miscarriage (RR: 0.58, CI: 0.32-1.06), but significant reduction in preterm birth by treatment with levothyoxine (RR: 0.31, CI: 0.11-0.90).

CONCLUSION

For hyperthyroidism, methimazole and PTU are effective in preventing pregnancy complications. For clinical hypothyroidism, treatment with levothyroxine is recommended. For subclinical hypothyroidism and thyroid autoimmunity, evidence is insufficient to recommend treatment with levothyroxine. The overall lack of evidence precludes a recommendation for universal screening and is only justified in a research setting.

Thyroid dysfunction in pregnancy

Timely treatment of thyroid disease during pregnancy is important in preventing adverse maternal and fetal outcomes. Thyroid abnormalities are very often subclinical in nature and not easily recognized without specific screening programs. Even mild maternal thyroid hormone deficiency may lead to neurodevelopment complications in the fetus. The main diagnostic indicator of thyroid disease is the measurement of serum thyroid-stimulating hormone and free thyroxine levels. Availability of gestation-age-specific thyroid-stimulating hormone thresholds is an important aid in the accurate diagnosis and treatment of thyroid dysfunction. Pregnancy- specific free thyroxine thresholds not presently available are also required. Large-scale intervention trials are urgently needed to assess the efficacy of preconception or early pregnancy screening for thyroid disorders. Accurate interpretation of both antepartum and postpartum levels of thyroid hormones is important in preventing pregnancy-related complication secondary to thyroid dysfunction. This article sheds light on the best ways of management of thyroid dysfunction during pregnancy in order to prevent any possible maternal or fetal complication.

Thyroid disorders during pregnancy

Thyroid disorders are common in women during pregnancy. If left untreated, both hypothyroidism and hyperthyroidism are associated with adverse effects on pregnancy and fetal outcomes. It is important to correctly identify these disorders and treat them appropriately to prevent pregnancy-related complications. Levothyroxine is the indicated treatment for hypothyroidism, and thionamides are the treatment of choice for hyperthyroidism; thyroidectomy may be indicated in select cases. When thyroid cancer is diagnosed during pregnancy, a decision must be made regarding performing thyroidectomy during the pregnancy or postponing surgical resection until the postpartum period. Radioactive iodine is absolutely contraindicated during pregnancy and lactation.

Effects of maternal subclinical hypothyroidism on obstetrical outcomes during early pregnancy

BACKGROUND

Maternal hypothyroidism [overt hypothyroidism and subclinical hypothyroidism (SCH)] during early pregnancy is suspected to associate with adverse obstetrical outcomes.

AIM

The aim of the present study was to investigate whether maternal SCH during the early stage of pregnancy increase obstetrical complications and whether treatment results in an improvement in these outcomes.

SUBJECTS AND METHODS

A total of 756 women in the 1st trimester (≤12 weeks) of pregnancy were enrolled through 10 hospitals in Shenyang from 2007 to 2009. All participants underwent thyroid function testing in early pregnancy and their obstetrical outcomes were studied following delivery.

RESULTS

The incidence of spontaneous abortions in the SCH group was higher than the normal TSH group (15.48% vs 8.86%, p=0.03). No significant association was observed between SCH and other obstetrical complications including gestational hypertension, premature delivery, anemia, post-partum hemorrhage, low neonatal Apgar scores and low birth weight. Although levo-T4 (L-T4) treatment decreased the incidence of spontaneous abortions in women with SCH, it was not statistically significant when compared to women who did not receive treatment in the SCH group. None of the 28 women who received L-T4 treatment had premature delivery, low birth weight, hemorrhage, and low Apgar score.

CONCLUSIONS

The incidence of spontaneous abortion in pregnant women with SCH increases in early pregnancy.