Thyroid function after assisted reproductive technology in women free of thyroid disease

TSH levels after fresh embryo transfer are associated with reproductive outcomes in euthyroid women undergoing the first IVF/ICSI cycles

To investigate whether there is a relationship between TSH levels on the 14th day post embryo transfer (D14 TSH levels) and the reproductive outcomes in euthyroid women who are free from levothyroxine (LT4) treatment and undergo the first in vitro fertilization /intracytoplasmic sperm injection embryo transfer (IVF/ICSI-ET) cycles with the homogeneous ovarian stimulation protocols. This was a prospective study including a total of 599 euthyroid women undergoing the first IVF/ICSI ET cycles. Serum samples were collected and frozen on the 14th day post embryo transfer. TSH levels were measured after the confirmation of clinical pregnancy. The patients were divided into three groups (low-normal ≤ 2.5 mIU/L; high-normal 2.5-4.2 mIU/L; and high > 4.2 mIU/L) based on D14 TSH levels. Reproductive outcomes were compared among the three groups. Binary logistic regression analyses and generalized additive mixed models with smoothing splines were used to investigate the relationship between TSH levels and reproductive outcomes. D14 TSH levels were significantly elevated compared to basal TSH levels, and the degree of TSH elevation was significantly higher in pregnant women compared to that in non-pregnant women. The clinical pregnancy and live birth rates increased significantly in the high-normal D14 TSH groups, and doubled in the high D14 TSH groups compared to the low TSH groups. When adjusted by age, basal TSH, AMH, E2, endometrial thickness, type and causes of infertility, and transferred embryos, the dose-dependent relationships between D14 TSH and clinical pregnancy and live birth were observed. Obstetric outcomes in singleton or twins live birth among the different D14 TSH groups were similar. Elevated D14 TSH levels were associated with better clinical pregnancy and live birth rates, and were not associated with worse obstetric outcomes. The mechanisms to explain the phenomenon remained to be studied.

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.

Changes in thyroid function during controlled ovarian hyperstimulation (COH) and its impact on assisted reproduction technology (ART) outcomes: a systematic review and meta-analysis

BACKGROUND

To investigate the thyroid function changes during controlled ovarian hyperstimulation (COH) and ascertain its impact on reproductive outcomes.

METHODS

We conducted meta-analysis in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive literature search was performed to identify studies reported changes in thyroid parameters during COH. We analyzed thyroid-stimulating hormone (TSH) levels, free thyroxin (fT4) levels, changes in estrogens (E2), thyroxine-binding globulin (TBG), relative risks (RRs) of clinical pregnancy rate (CPR), live birth rate (LBR), and mean difference (MD) of TSH increment between the miscarriage group and ongoing pregnancy group.

RESULTS

This meta-analysis included fifteen individual studies (n = 1665 subjects). At the end of COH, the mean TSH (2.53 mIU/L; 95% CI, 2.19 to 2.88; I² = 92.9%) exceeded the upper limit (2.5 mIU/L) and remained above the threshold until one month following embryo transfer (ET). Thyroxin decreased from baseline to the end of COH (-0.18 ng/l; 95% CI, -0.35 to 0.00; I² = 92.2%). The CPR and LBR of patients with TSH exceeding the cutoff after COH were significantly lower than those of patients with TSH below the threshold (CPR: RR, 0.62; 95% CI, 0.47 to 0.82; I² = 0.0% and LBR: RR, 0.64; 95% CI, 0.44 to 0.92; I² = 0.0%). The MD of the increment in TSH levels between the miscarriage and ongoing pregnancy groups was 0.40 mIU/L (95% CI, 0.15 to 0.65; I² = 0.0%).

CONCLUSIONS

This meta-analysis shows that TSH increases and fT4 decreases during COH. COH-induced thyroid disorder impairs reproductive outcomes.

Thyroid function modifications in women undergoing controlled ovarian hyperstimulation for in vitro fertilization: a systematic review and meta-analysis

OBJECTIVE

To investigate the impact of controlled ovarian hyperstimulation (COH) for in vitro fertilization (IVF) on thyroid function.

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

Infertile women undergoing conventional IVF or intracytoplasmic sperm injection.

INTERVENTION(S)

Systematic search of PubMed, MEDLINE, Embase, Scopus, and Web of Science from inception until November 2020. Studies could be included only if they met the following criteria: subjects were classified as euthyroid or hypothyroid; serum thyroid-stimulating hormone (TSH) and/or free thyroxine (FT4) levels were evaluated before COH; and the same thyroid function test was reassessed after COH (i.e., at the time of trigger for final follicle maturation and/or at pregnancy test).

MAIN OUTCOME MEASURE(S)

Mean difference (MD) between the serum TSH or FT4 levels assessed after COH and before COH.

RESULT(S)

In euthyroid women, the serum TSH levels assessed at the time of trigger and at the time of pregnancy test were significantly higher than those at baseline (MD: 0.69 mIU/L, 95% confidence interval [CI]: 0.30-1.08, I² = 93% and MD: 0.67, 95% CI: 0.49-0.85, I² = 72%, respectively). The serum FT4 levels did not undergo significant changes. Subanalysis confirmed an increase in the TSH level after restricting the analysis to women treated with gonadotropin-releasing hormone agonist protocols and to those who achieved pregnancy. A pronounced increase in the TSH level was observed in women treated for hypothyroidism (MD: 1.50 mIU/L, 95% CI: 1.10-1.89, I² = 0%).

CONCLUSION(S)

Pooling of the results showed a significant increase in serum TSH level in women undergoing COH for IVF. This change was particularly pronounced in women treated for hypothyroidism. New thyroid function screening strategies for women undergoing COH are warranted.

2021 European Thyroid Association Guideline on Thyroid Disorders prior to and during Assisted Reproduction

Severe thyroid dysfunction may lead to menstrual disorders and subfertility. Fertility problems may persist even after restoring normal thyroid function, and then an assisted reproductive technology (ART) may be a solution. Prior to an ART treatment, ovarian stimulation is performed, leading to high oestradiol levels, which may lead to hypothyroidism in women with thyroid autoimmunity (TAI), necessitating levothyroxine (LT4) supplements before pregnancy. Moreover, women with the polycystic ovarian syndrome and idiopathic subfertility have a higher prevalence of TAI. Women with hypothyroidism treated with LT4 prior to ART should have a serum TSH level <2.5 mIU/L. Subfertile women with hyperthyroidism planning an ART procedure should be informed of the increased risk of maternal and foetal complications, and euthyroidism should be restored and maintained for several months prior to an ART treatment. Fertilisation rates and embryo quality may be impaired in women with TSH >4.0 mIU/L and improved with LT4 therapy. In meta-analyses that mainly included women with TSH levels >4.0 mIU/L, LT4 treatment increased live birth rates, but that was not the case in 2 recent interventional studies in euthyroid women with TAI. The importance of the increased use of intracytoplasmic sperm injection as a type of ART on pregnancy outcomes in women with TAI deserves more investigation. For all of the above reasons, women of subfertile couples should be screened routinely for the presence of thyroid disorders.

Impact of Thyroid Autoimmunity on In Vitro Fertilization/Intracytoplasmic Sperm Injection Outcomes and Fetal Weight

Several studies have reported the association between thyroid autoimmunity (TAI) and in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) outcomes. However, the findings remain controversial. We performed a large-scale retrospective cohort study to verify the effect of the presence of thyroid antibodies on IVF/ICSI outcomes and fetal growth and to evaluate the association between the types and titers of thyroid antibodies and adverse IVF/ICSI outcomes. A total of 16481 patients with infertility were referred to the Reproductive Center of Peking University Third Hospital for their first IVF/ICSI treatment between January 2018 and June 2019.Patients who sought IVF/ICSI treatment due to tubal or male factors infertility and who achieved fresh embryo transfer were included in our study. Finally, 778 patients with thyroid antibody positivity were selected as the TAI group, and 778 age-matched patients were included in the control group. The number of oocytes retrieved and high-graded embryos and the rates of clinical pregnancy, miscarriage, live birth, and preterm delivery were compared between the TAI and control groups. In addition, subgroup analysis was performed to demonstrate whether different types and titers of thyroid antibodies had different effects on IVF/ICSI outcomes. After adjusting for thyroid function, anti-Müllerian hormone levels, basal follicle stimulating hormone levels, basal estradiol levels and antral follicle count, the number of oocytes retrieved in the TAI group was significantly lower than that in the control group. No significant differences were observed between the two groups in the rates of clinical pregnancy, miscarriage, preterm delivery, live birth, and birth weight in singletons; however, the birth weight in twin pregnancy was significantly lower in the TAI group than in the control group. Subgroup analysis showed no association between the types or titers of thyroid antibodies and adverse IVF/ICSI outcomes. In conclusion, the presence of TAI in patients with infertility did not impair embryo quality or affect pregnancy outcomes, including clinical pregnancy, miscarriage, preterm delivery, and live birth. However, it decreased the number of oocytes retrieved and birth weight in twin pregnancy.

Effects of controlled ovarian stimulation on thyroid stimulating hormone in infertile women

OBJECTIVE

To study the effects of long-acting gonadotropin-releasing hormone agonist (GnRH-a) on thyroid function in euthyroid patients of in vitro fertilization (IVF)/ intracytoplasmic sperm injection of embryo transfer (ICSI-ET) and to investigate the timing and alteration of thyroid stimulating hormone (TSH) during controlled ovarian stimulation(COS).

MATERIALS AND METHODS

Euthyroid patients scheduled for IVF/ICSI were enrolled. Euthyroidism was defined as having no history of hypothyroidism with normal TSH before IVF. Long GnRH-a protocol was chosen as COS protocol. 207 patients were divided into two groups based on basal serum TSH level: group A with 0.35mIU/L＜TSH＜2.5mIU/L (n = 137) and group B with 2.5mIU/L ≤ TSH＜4.5mIU/L (n = 70). Serum TSH was tested on 6 time points: before COS (2-5days in menstrual cycle, before GnRH-a injection), Gn injection day 1, Gn injection day 5, human chorionic gonadotropin (HCG) day, 14 and 28 days after transplantation. The serum TSH, clinical pregnancy and abortion rate were investigated.

RESULT

The serum TSH value was significantly (P < 0.05) increased after injection of long-acting GnRH-a in all patients. Both groups had significant (P < 0.05) increases in serum TSH level after long-acting GnRH-a injection. The TSH level was increased in 131(63.3%) patients after GnRH-a injection, of which twenty (9.7%) had subclinical hypothyroidism with TSH level over 4.5 mIU/L. The other 76 (36.7%) patients had decreased TSH. In group A, 79 (57.7%) patients showed an increase of TSH, including three patients (2.2%) with simultaneous rise of TPOAb and four (2.9%) diagnosed of subclinical hypothyroidism with TSH level over 4.5 mIU/L, and the rest fifty-eight (42.3%) patients had decreased TSH with one patient with elevated TPOAb who was diagnosed with subclinical hyperthyroidism. In group B, fifty-two (74.3%) patients showed an increase of TSH, including thirteen (18.6%) patients with elevated TPOAb and sixteen (22.9%) patients diagnosed of subclinical hypothyroidism with TSH level over 4.5 mIU/L, and the rest eighteen (25.7%) patients had decreased TSH with one patient diagnosed with subclinical hyperthyroidism. Group B had a significant higher proportion of patients with elevated serum TSH than group A (P ＜ 0.05). Compared to the baseline level, serum TSH ascended distinctly and reached peak level on HCG day in all patients. Group A and B had similar trends of alteration. Patients in group A had significantly (P＜0.05) higher clinical pregnancy rate than in group B. No significant (P＞0.05) difference in abortion rate were observed between the two groups.

CONCLUSION

GnRH-a can significantly increase serum TSH levels with possible development of subclinical thyroid dysfunction. Infertile patients with serum TSH > 2.5 mIU/L are more susceptible to GnRH-a while patients with basal TSH less than 2.5 mIU/L may get a higher clinical pregnancy rate when receiving IVF/ICSI.

Preconceptional antithyroid peroxidase antibodies, but not thyroid-stimulating hormone, are associated with decreased live birth rates in infertile women

OBJECTIVE

To study whether preconceptual thyroid-stimulating hormone (TSH) and antithyroid peroxidase (TPO) antibodies are associated with poor reproductive outcomes in infertile women.

DESIGN

Secondary analysis of data from two multicenter, randomized, controlled trials conducted by the Reproductive Medicine Network of the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Multivariable logistic regression analyses were performed to assess the association between preconceptual TSH levels and anti-TPO antibodies.

SETTING

Not applicable.

PATIENT(S)

Serum samples from 1,468 infertile women were utilized.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Cumulative conception, clinical pregnancy, miscarriage, and live birth rates were calculated.

RESULT(S)

Conception, clinical pregnancy, miscarriage, and live birth rates did not differ between patients with TSH ≥2.5 mIU/L vs. TSH < 2.5 mIU/L. Women with anti-TPO antibodies had similar conception rates (33.3% vs. 36.3%) but higher miscarriage rates (43.9% vs. 25.3%) and lower live birth rates (17.1% vs. 25.4%) than those without anti-TPO antibodies. Adjusted, multivariable logistic regression models confirmed elevated odds of miscarriage (odds ratio 2.17, 95% confidence interval 1.12-4.22) and lower odds of live birth (oddr ratio 0.58, 95% confidence interval 0.35-0.96) in patients with anti-TPO antibodies.

CONCLUSION(S)

In infertile women, preconceptional TSH ≥2.5 mIU/L is not associated with adverse reproductive outcomes; however, anti-TPO antibodies are associated with increased risk of miscarriage and decreased probability of live birth.

CLINICAL TRIAL REGISTRATION NUMBER

PPCOS II NCT00719186; AMIGOS NCT01044862.

2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum

BACKGROUND

Thyroid disease in pregnancy is a common clinical problem. Since the guidelines for the management of these disorders by the American Thyroid Association (ATA) were first published in 2011, significant clinical and scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid disease in women during pregnancy, preconception, and the postpartum period.

METHODS

The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations. The guideline task force had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members.

RESULTS

The revised guidelines for the management of thyroid disease in pregnancy include recommendations regarding the interpretation of thyroid function tests in pregnancy, iodine nutrition, thyroid autoantibodies and pregnancy complications, thyroid considerations in infertile women, hypothyroidism in pregnancy, thyrotoxicosis in pregnancy, thyroid nodules and cancer in pregnant women, fetal and neonatal considerations, thyroid disease and lactation, screening for thyroid dysfunction in pregnancy, and directions for future research.

CONCLUSIONS

We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid disease in pregnant and postpartum women. While all care must be individualized, such recommendations provide, in our opinion, optimal care paradigms for patients with these disorders.

[Thyroid function for infertile women during ovarian hyperstimulation as part of IVF]

OBJECTIVES

Optimal thyroid function is necessary for an effective fertility. Many authors have suggested that thyroid function has an impact on IVF outcome. Conversely, IVF has been suggested to induce changes in thyroid function. The aim of this study was to determine the nature and the timing of alterations in thyroid function, throughout controlled ovarian hyperstimulation, from the beginning of therapy to the day of triggering ovulation. And make a clarification of the current recommendations of the thyroid function during hormonal stimulation.

METHODS

Subjects were recruited from March 2013 to July 2013 at the Hospital of the University of Reims. The studied population consisted of 50 infertile patients who had undergone IVF/ICSI cycles. Thyroid axis exploration was realized before therapy and at every hormonal dosage during ovarian monitorage.

RESULTS

Prematuary fluctuations were observed without impact on pregnancy rate. We could detect potential hypothyroid women thanks to this dosage and define a connection between pregnancy rate and TSH with a threshold closer to 1mUI/L than 2,5mUI/L defined by the endocrine society.

CONCLUSIONS

The link between thyroid function, forecast of conception and pregnancy is well documented. Currently, there is no recommendation on the rate of TSH targets for the patients in medical assisted procreation.

THE LONG-TERM IMPACT OF CONTROLLED OVARIAN HYPERSTIMULATION ON THYROID FUNCTION

OBJECTIVE

Evidence on the long-term impact of controlled ovarian hyperstimulation (COH) on thyroid function is scarce. To investigate this, we report on serum thyroid-stimulating hormone (TSH) modifications in euthyroid and hypothyroid women during COH and 3 months after the end of the stimulation cycle.

METHODS

Women who underwent in vitro fertilization (IVF) and who did not become pregnant were eligible. Cases were women with treated hypothyroidism and basal serum TSH <2.5 mIU/L. Controls were euthyroid women matched to cases by age and basal serum TSH. Women could be included if serum TSH was available at 4 time points: prior to initiating COH (time 1); at the time of human chorionic gonadotropin (hCG) administration (time 2); 16 days after hCG administration (time 3); and 3 months after the end of the IVF cycle (time 4).

RESULTS

Thirty-seven case-control pairs were included. Serum TSH at times 1, 2, 3, and 4 was 1.7 ± 0.6, 3.1 ± 1.4, 3.1 ± 1.3, and 2.7 ± 1.7 mIU/L, and 1.7 ± 0.6, 2.9 ± 1.0, 2.7 ± 1.0, and 1.9 ± 0.7 mIU/L among cases and controls, respectively. A statistically significant difference emerged at time 4 (P<.001). In both groups, serum TSH was higher at time 4 compared to time 1. Serum TSH exceeded the recommended threshold of 2.5 mIU/L at time 4 in 51% of cases (95% confidence interval [CI], 35 to 68%) and in 16% of controls (95% CI, 4 to 28%) (P = .003).

CONCLUSION

COH seems to have a long-term impact on TSH levels. The magnitude of this effect is particularly pronounced in hypothyroid women.

Levothyroxine dose adjustment in hypothyroid women achieving pregnancy through IVF

OBJECTIVE

About one out of two women with primary hypothyroidism has to increase the dosage of exogenous levothyroxine (L-T4) during pregnancy. Considering the detrimental impact of IVF on thyroid function, it has been claimed but not demonstrated that L-T4 dose adjustment may be more significant in hypothyroid women who become pregnant after IVF.

DESIGN

Retrospective cohort study.

METHODS

Hypothyroid-treated women who achieved a live birth through IVF were reviewed. Women could be included if thyroid function was well compensated with L-T4 before the IVF cycle (i.e., serum TSH <2.5  mIU/l and serum free T4 within the normal range). Serum TSH and dose adjustment were evaluated at five time points during pregnancy. The trimester ranges for serum TSH considered as reference to adjust L-T4 therapy were 0.1-2.5  mIU/l for the first trimester, 0.2-3.0  mIU/l for the second trimester, and 0.3-3.0  mIU/l for the third trimester.

RESULTS

Thirty-eight women were selected. During the whole pregnancy 32 women (84%; 95% CI: 72-96%) required an increase in the dose of L-T4. In most cases (n=28), this occured within the first 5-7 weeks of gestation (74%, 95% CI: 58-85%). At 5-7 weeks of gestation, the median (interquartile range) increase of L-T4 dose for the whole cohort was 26% (0-50%). At 30-32 weeks, it was 33% (14-68%). In order to identify predictive factors of dose adjustment, we compared women who did (n=28) and did not (n=10) adjust L-T4 dosage at 5-7 weeks' gestation. Significant differences emerged for thyroid autoimmunity prevalence and for the distribution of hypothyroidism aetiology.

CONCLUSIONS

The vast majority of hypothyroid-treated women who achieve pregnancy through IVF need an increase in the L-T4 dose during gestation. This requirement tends to occur very early during gestation.

[Impact of thyroid function on fertility]

Until recently, anovulation or recurrent miscarriages were the only situations for screening a thyroid dysfunction in an infertile patient. Recent U.S. guidelines published in 2011 identify infertile women as being at risk for thyroid dysfunction. This paper proposes, on the occasion of the new recommendations, a review of the literature data on the known impact of thyroid dysfunction on fertility, on the first trimester of pregnancy and on the way to treat them.

Thyroid axis dysregulation during in vitro fertilization in hypothyroid-treated patients

BACKGROUND

While there is a large body of evidence showing a significant impact of controlled ovarian hyperstimulation (COH) on thyroid function in euthyroid patients undergoing in vitro fertilization (IVF), information on the effect of this treatment on thyroid axis equilibrium in hypothyroid-treated patients is insufficient. The goal of this prospective study was to investigate serum thyroid-stimulating hormone (TSH) modifications in hypothyroid-treated patients during IVF.

METHODS

Hypothyroid-treated women selected for IVF between November 2010 and December 2011 were considered for study entry. They were eligible if serum TSH tested the month preceding the IVF cycle was 0.4-2.5 mIU/L. Additional inclusion criteria were as follows: (1) a certified diagnosis of clinical or subclinical hypothyroidism; (2) consumption of at least 25 μg of levothyroxine daily; (3) serum free triiodothyronine and free thyroxine tested the month preceding the IVF cycle within the reference range; (4) no previous IVF cycles; (5) regular menstrual cycles; and (6) day 3 serum follicle-stimulating hormone <12 IU/mL and anti-Müllerian hormone >0.5 ng/mL. Serum TSH was tested at three time points: between day 1 and day 8 of the cycle during the month preceding the start of controlled ovarian hyperstimulation (COH), at the time of human chorionic gonadotropin (hCG) administration and at 16 days after hCG administration.

RESULTS

Seventy-two women met our selection criteria. The serum levels of TSH at basal assessment, at the time of hCG administration, and at 16 days after hCG administration were 1.7 ± 0.7, 2.9 ± 1.3, and 3.2 ± 1.7 mIU/L, respectively. All pairwise comparisons were statistically significant. Serum TSH exceeded the threshold of 2.5 mIU/L in 46 subjects at the time of hCG administration (64%, [CI: 53-75%]) and in 49 subjects 16 days after hCG administration (68%, [CI: 57-79%]).

CONCLUSIONS

Serum TSH increased considerably during COH in adequately treated hypothyroid women undergoing IVF. We suggest strictly monitoring these women during IVF cycles and, if necessary, promptly adjusting the levothyroxine dose. This is the most pragmatic approach but, to date, it is not supported by clinical evidence. Further studies aimed at clarifying the most suitable therapeutic strategy are thus warranted.

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.

Periconceptional changes in thyroid function: a longitudinal study

BACKGROUND

Limitations in our current knowledge of normative physiologic changes in thyroid function during the periconception window narrow our ability to establish an optimal approach to screening and diagnosis of thyroid disease in pregnant women. The objective of this study was to characterize changes in thyroid function during the transition from the pre-pregnant to pregnant state in normal fertile women.

METHODS

Women (N = 60) ages 30-42 years without a history of thyroid disease, who were planning pregnancy, were observed prospectively before and during early pregnancy. Thyroid function (thyroid stimulating hormone, TSH and free thyroxine, FT4) was measured before conception and between 6 and 9 weeks gestation. Pre-pregnancy samples were analyzed for thyroid antibodies. Bivariate analyses and longitudinal curves (general estimating equation models) were used to analyze changes in thyroid function during the periconception window by antibody status.

RESULTS

Pre-pregnancy TSH values were significantly higher than early pregnancy TSH (p < 0.001), but FT4 values did not differ (p = 0.53). TSH declined as gestational age increased (P < 0.01). Thyroid antibody positive women had a higher pre-pregnancy TSH compared to antibody negative women (p < 0.01). Periconceptional change in thyroid function was more variable among women with antibodies (p < 0.001). 50% of women with elevated pre-pregnancy TSH values (TSH > 3.0 mIU/L) had normal TSH values (TSH < 2.5 mIU/L) in pregnancy.

CONCLUSIONS

TSH values decline during the transition from pre-pregnancy to early pregnancy. The change in TSH appears to be less predictable in women with thyroid antibodies. Periconceptional changes in thyroid function should be considered in formulating prenatal thyroid screening guidelines.

Thyroid function during controlled ovarian hyperstimulation as part of in vitro fertilization

OBJECTIVE

To determine the exact nature and timing of alterations in thyroid function throughout controlled ovarian hyperstimulation (COH).

DESIGN

Prospective cohort study.

SETTING

University fertility clinic.

PATIENT(S)

Fifty-seven women undergoing COH as part of planned in vitro fertilization.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Timing and magnitude of change in serum thyroid hormones, including TSH, total and free T(4), E(2), and thyroxine-binding globulin (TBG), measured at six time points from before stimulation to 2 weeks after serum pregnancy test.

RESULT(S)

Geometric mean serum TSH increased during stimulation, peaking 1 week after hCG administration compared with baseline (2.44 vs. 1.42 mIU/L), as did free T(4) (1.52 vs. 1.38 ng/dL) and TBG (32.86 vs. 21.52 μg/mL). Estradiol levels increased, peaking at hCG administration (1743.21 vs. 71.37 pg/mL). Of 50 women with baseline TSH ≤ 2.5 mIU/L, 22 (44.0%) had a subsequent rise in TSH to >2.5 during or after COH. The pattern of change over time in TSH concentrations was significantly influenced by baseline hypothyroidism and whether pregnancy was achieved.

CONCLUSION(S)

COH led to significant elevations in TSH, often above pregnancy appropriate targets. These findings were particularly evident in women with preexisting hypothyroidism and may have important clinical implications for screening and thyroid hormone supplementation.

Effect of autoimmune thyroid disease in older euthyroid infertile woman during the first 35 days of an IVF cycle

In this case-control study of euthyroid first-cycle IVF patients ≥ 38 years old with singleton baby, miscarriage, biochemical pregnancy, and no pregnancy outcomes from 2005-2008, we assayed frozen serum for autoimmune thyroid disease (AITD) and thyroid function at cycle start, trigger, and 4 and 5 weeks' gestation. AITD prevalence in older infertile women was similar across clinical outcomes, and although AITD was associated with a higher baseline TSH, TSH remained within acceptable ranges, suggesting that T(4) supplementation may not affect maternal outcomes in older euthyroid AITD patients through 5 weeks gestation.

Thyroid function and human reproductive health

Via its interaction in several pathways, normal thyroid function is important to maintain normal reproduction. In both genders, changes in SHBG and sex steroids are a consistent feature associated with hyper- and hypothyroidism and were already reported many years ago. Male reproduction is adversely affected by both thyrotoxicosis and hypothyroidism. Erectile abnormalities have been reported. Thyrotoxicosis induces abnormalities in sperm motility, whereas hypothyroidism is associated with abnormalities in sperm morphology; the latter normalize when euthyroidism is reached. In females, thyrotoxicosis and hypothyroidism can cause menstrual disturbances. Thyrotoxicosis is associated mainly with hypomenorrhea and polymenorrhea, whereas hypothyroidism is associated mainly with oligomenorrhea. Thyroid dysfunction has also been linked to reduced fertility. Controlled ovarian hyperstimulation leads to important increases in estradiol, which in turn may have an adverse effect on thyroid hormones and TSH. When autoimmune thyroid disease is present, the impact of controlled ovarian hyperstimulation may become more severe, depending on preexisting thyroid abnormalities. Autoimmune thyroid disease is present in 5-20% of unselected pregnant women. Isolated hypothyroxinemia has been described in approximately 2% of pregnancies, without serum TSH elevation and in the absence of thyroid autoantibodies. Overt hypothyroidism has been associated with increased rates of spontaneous abortion, premature delivery and/or low birth weight, fetal distress in labor, and perhaps gestation-induced hypertension and placental abruption. The links between such obstetrical complications and subclinical hypothyroidism are less evident. Thyrotoxicosis during pregnancy is due to Graves' disease and gestational transient thyrotoxicosis. All antithyroid drugs cross the placenta and may potentially affect fetal thyroid function.

Risk of spontaneous miscarriage in euthyroid women with thyroid autoimmunity undergoing IVF: a meta-analysis

OBJECTIVE

To investigate whether thyroid autoimmunity (TAI) is associated with increased risk for spontaneous miscarriage in subfertile, euthyroid women undergoing IVF.

DESIGN

Meta-analysis of observational studies.

PATIENT(S)

Four prospective studies that reported data on 1098 subfertile women undergoing IVF (141 with TAI and 957 controls) were included in the meta-analysis.

MAIN OUTCOME MEASURE

Miscarriage risk ratio (RR).

SECONDARY OUTCOME MEASURES

Clinical pregnancy rate and delivery rate.

RESULT(S)

Euthyroid, subfertile women with TAI undergoing IVF demonstrated significantly higher risk for miscarriage compared with controls (four studies-fixed effects RR: 1.99, 95% confidence interval: 1.42- 2.79, P<0.001). No significant difference in clinical pregnancy and delivery rates was detected between groups.

CONCLUSION

Based on the currently available evidence, it appears that the presence of TAI is associated with an increased risk for spontaneous miscarriage in subfertile women achieving a pregnancy through an IVF procedure.

The usefulness of a thyrotropin-releasing hormone stimulation test in subfertile female patients

BACKGROUND

The thyrotropin-releasing hormone (TRH) stimulation test is widely used as a screening procedure in subfertile patients to identify subclinical hypothyroidism. However, its usefulness in daily clinical practice has not been proven, despite more than 30 years of use.

MATERIAL AND METHODS

We analyzed data from a cohort of 371 consecutive female subfertility patients, who were screened with an intravenous TRH test when they came for the first evaluation. All patients with positive thyroid peroxidase antibodies, basal TSH <1.5 mU/l, known thyroid disease or actual thyroid medication were not screened and excluded from the analysis.

RESULTS

We found a good correlation between basal and stimulated levels of thyroid-stimulating hormone (TSH). Basal TSH and the difference between stimulated and basal TSH did not correlate with prolactin levels. Definition of a positive TRH test (difference of 15 or 20 mU/l) did not have sufficient sensitivity and specificity, as confirmed by analysis of receiver operating characteristic curves, to identify subclinical hypothyroidism.

CONCLUSION

TRH stimulation testing is not helpful to identify patients with subclinical hypothyroidism and should not be part of initial screening in this group.

Thyroid disease and female reproduction

The menstrual pattern is influenced by thyroid hormones directly through impact on the ovaries and indirectly through impact on SHBG, PRL and GnRH secretion and coagulation factors. Treating thyroid dysfunction can reverse menstrual abnormalities and thus improve fertility. In infertile women, the prevalence of autoimmune thyroid disease (AITD) is significantly higher compared to parous age-matched women. This is especially the case in women with endometriosis and polycystic ovarian syndrome (PCOS). AITD does not interfere with normal foetal implantation and comparable pregnancy rates have been observed after assisted reproductive technology (ART) in women with and without AITD. During the first trimester, however, pregnant women with AITD carry a significantly increased risk for miscarriage compared to women without AITD, even when euthyroidism was present before pregnancy. It has also been demonstrated that controlled ovarian hyperstimulation (COH) in preparation for ART has a significant impact on thyroid function, particularly in women with AITD. It is therefore advisable to measure thyroid function and detect AITD in infertile women before ART, and to follow-up these parameters after COH and during pregnancy when AITD was initially present. Women with thyroid dysfunction at early gestation stages should be treated with l-thyroxine to avoid pregnancy complications. Whether thyroid hormones should be given prior to or during pregnancy in euthyroid women with AITD remains controversial. To date, there is a lack of well-designed randomized clinical trials to elucidate this controversy.

Euthyroid women with autoimmune disease undergoing assisted reproduction technologies: the role of autoimmunity and thyroid function

Thyroid dysfunction and the presence of thyroid antibodies increase the risk of infertility and miscarriage. The aim of the present study was to assess if patients with autoimmune thyroid disease undergoing assisted reproduction technologies (ART) are afflicted by poor pregnancy and/or delivery rate and if the outcome is conditioned by pre-ART thyroid status. The study was retrospective (from January 2000 to January 2005) and was carried out at the Division of Physiopathology of Human Reproduction. Women who underwent ART were tested for TSH, free T4 (FT4), thyroid peroxidase antibodies (TPOAb) before and during pregnancy. A total of 416 euthyroid women were selected; 42 (10.1%) were TPOAb (+). Women >35 yr were excluded. The endpoints were pregnancy and delivery rates.

RESULTS

no differences in pregnancy and delivery rates were observed between women with and without antibodies. In TPOAb (+), women who failed to become pregnant or miscarried displayed higher TSH values before ART (2.8 mIU/l) compared to the ones who delivered (1.6 mIU/l; p=0.032) and compared to TPOAb (-) (1.1 mIU/l; p=0.018).

CONCLUSIONS

in euthyroid women undergoing ART the pregnancy and delivery rates are not affected by the presence of TPOAb. In TPOAb (+) high-normal TSH values are associated with increased risk of unsuccessful pregnancy or subsequent miscarriage. Further studies are required to ascertain possible benefits of levo-T4 (L-T4) in such patients.