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Glucocorticoid supplementation improves reproductive outcomes in infertile women with antithyroid autoimmunity undergoing ART

Abstract Background: Thyroid autoimmune disease (TAI) has been verified to be related to multiple adverse pregnancy outcomes. A growing number of evidences highlight the protective roles of glucocorticoid on the treatments of TAI. This meta-analysis aimed to study whether it is beneficial to add glucocorticoid treatment in infertile women with TAI when they are undergoing assisted reproductive technology (ART). Methods: We conducted a systematic search in PubMed, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI), WanFang database, Weipu China Science and Technology Journal Databases (VIP database) up to September 10, 2020. The Revman 5.3 software was utilized for data statistics. We used a random-effects model to analyze data and the odds ratio (OR) combining with 95% confidence interval (95% CI) were employed to reveal the results. Results: Three publications with 237 antithyroid antibody (ATA)-positive and 384 ATA-negative women were included in the final analysis. Overall, glucocorticoid therapy showed satisfying effects on improving clinical pregnancy rate (OR = 4.63, 95% CI [2.23, 9.58], I2 = 0.0%, P < .0001) and live birth rate (OR = 3.19, 95% CI [1.13, 9.04], I2 = 0.0%, P = .03) of ATA-positive women compared with control group. However, it seems that glucocorticoid showed no significant difference in the abortion rate (OR = 0.62, 95% CI [0.09, 4.32], I2 = 35%, P = .64) and oocyte recovery (OR = 2.26, 95% CI [−1.46, 5.99], I2 = 79%, P < .0001) between the 2 groups. Conclusions: Glucocorticoid may improve the pregnancy outcomes of ART women with ATA positive, but there is no significant reduction in the risk of miscarriage. Due to the limited enrolled references, glucocorticoid adjuvant therapy should be applied after more randomized controlled trials.


Introduction
Thyroid autoimmune disease (TAI) is defined as the disorder of normal thyroid autoimmune function caused by the presence of thyroid autoantibodies (ATA), including thyroglobulin antibodies (Tg-Ab) and thyroid peroxidase antibodies (TPO-Ab). [1,2] In women of childbearing age, the prevalence of TPO-Ab positive, Tg-Ab positive, and TPO-Ab/Tg-Abs double positive were 4.4%, 3.4%, and 6.9%, respectively. [3] Noteworthy, Unuane et al [4] also found the prevalence of TAI was higher in infertile women as compared to fertile women (19% vs 13%, P = .047). Some studies have also indicated ATA is associated with infertility and other poor pregnancy outcomes, such as pregnancy loss, recurrent abortion, premature delivery, placental abruption, postpartum depression, or even neonatal respiratory distress syndrome. [5,6] It is considered as an independent marker of the failure of assisted reproductive technology (ART). [7,8] However, the conflicting data remain on the influence of ATA on the pregnancy outcomes of infertile women, especially on the adverse outcomes of ART. [9][10][11] A retrospective study investigated 873 euthyroid women with ART and found no significant difference in delivery rate, pregnancy loss, and biochemical pregnancy between ATApositive group and ATA-negative group. [9] The result was also supported by the recent studies of Chen et al [10] and Kris et al. [11] Conversely, theories have been put forward that ATA positive in euthyroid women with infertility was associated with adverse outcomes of pregnancy, and even caused the failure of ART. [12][13][14] The link between ATA and reproductive outcomes remains debated in various studies, and underlying mechanisms are still unclear and required to be more in-depth investigated.
Glucocorticoids, playing the crucial role on normal embryo implantation and fetal placental development, are used to treat autoimmune diseases, such as systemic lupus erythematosus and antiphospholipid syndrome. [15] Some studies have revealed medium and small dose glucocorticoid could reduce the level of ATA and improve pregnancy successful rate of ART in infertile women with TAI. [16][17][18][19] But Robertson and his colleagues [20] questioned the safety and efficacy of glucocorticoids, arguing that it is unnecessary and probably harmful unless in the state of overimmune pathology. In view of these inconsistent findings, we conducted a meta-analysis to investigate the effect of glucocorticoids on reproductive outcomes in ATA-positive women undergoing ART.

Study search methodology
Up to December 31, 2020, the literature search was performed by PubMed, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI), WanFang database, Weipu China Science and Technology Journal Databases (VIP database). There is no language and time limitation imposed in the literature search. Literature was filtered utilizing combinations of the following key terms: "prednisone" or "prednisolone" or "corticosteroid" or "glucocorticoid" or "antithyroid autoimmunity" or "anti-thyroid antibodies" or "thyroperoxidase antibody" or "thyroglobulin antibodies" or "anti-thyroid antibodies" or" thyroid autoimmune disease" or "IVF" or "ICSI" or "ART" or "assisted reproductive technology" or "infertility" or "infertility" or "pregnancy outcome" or "clinical outcome." Relevant references were also manually retrieved to identify qualified references.

Study selection
The inclusion criterias were as follows: (1) prospective or retrospective studies with a control group; (2) the subjects were infertile women with TPO-Ab or TG-Ab positive without thyroid dysfunction following ART; (3) obtain the compared results of pregnancy outcomes between women treated with glucocorticoid and no glucocorticoid (or placebo); (4) outcome indicators include pregnancy rate, live birth rate, or abortion rate.
When studies from the same institution were searched, the one with more sample size and the most credible and complete information was enrolled. Besides, case reports, meeting abstracts, conference proceedings, repeated publications were also excluded.

Data extraction
The following data were extracted from the literature: first author, country, years of publication, study population, study method, study design, study period, infertility causes, ART type, thyroid autoantibody detection method, reference value, and intervention measures. The main outcome index is the clinical pregnancy rate. The secondary index is the live birth rate and abortion rate. Clinical pregnancy was defined as a pregnancy sac with a heartbeat observed by ultrasound. Miscarriage was defined as the loss of clinical pregnancy. The 3 included articles in this paper all adopted the Newcastle-Ottawa quality assessment scale (NOS) for quality assessment.

Statistical analysis
All statistical analyses were performed using RevMan Version 5.3 (Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014). Odds ratio (OR) and corresponding 95% confidence interval (CI) were used to describe the results. Heterogeneity was determined by I 2 statistics, and the value less than 50% was considered as no significant heterogeneity. The random-effect model was employed to calculate the summaryeffect estimates, and the significance level was set at P < .05. The study was approved by the ethics review committee of the First Affiliated Hospital of Chongqing Medical University. Figure 1 summarizes the process of literature retrieval and research selection. A total of 212 articles were retrieved in this study, of which 22 publications were obtained by manual retrieval. After removing duplicates and reviewing titles and abstracts, 67 relevant articles were selected. Among them, we excluded 42 studies without ART, 12 studies without glucocorticoid-treated, and 10 studies that were meta-analyses or reviews. Finally, only 3 articles published between 2000 and 2020 met inclusion and exclusion criteria, including 237 ATA-positive and 384 ATA-negative women. The basic information of the included studies is shown in Table 1, and the quality evaluation is illustrated in Table 2.

Ovarian response and embryo quality
In the study of Revelli et al, [17] it was found that the ovarian response to stimulation (Gn dose/oocyte) in the glucocorticoidtreated group was remarkably higher than that in the untreated group (448 ± 520 vs 1028 ± 1141). Another study of Litwicka [19] showed that the embryo quality in the glucocorticoid group was slightly higher than that in the untreated group (Table 3). Unfortunately, neither of these 2 studies was further explored;  Quality assessment of included studies.

Source
Representativeness of the exposed cohort Selection of the non-exposed cohort  [17] Unclear Unclear 6 Turi 2010 [18] 9 Litwicka 2015 [19] Unclear Unclear 7 There are 8 items in total (0-9 points). Except for the 2 clauses under comparability, each item is a star. Table 3 Participant characteristics in the included studies.
Author, year of publication therefore, the effect of glucocorticoid on oocyte number and embryo therapy remains to be discussed.

Live birth rate
Two studies investigated the effect of glucocorticoid supplementation on the live birth rate in infertile women with TAI undergoing ART. [18,19] The pooled effect revealed a significantly increased live births rate among women treated with glucocorticoid (OR = 3.19, 95% CI [1.13, 9.04], I 2 = 0.0%, P = .03) (Fig. 3B).

Miscarriage rate
Three studies reported the roles of glucocorticoid supplementation on the abortion rate in infertile women with TAI undergoing ART. [17][18][19] Our meta-analysis revealed there was no significant decrease in the abortion pregnancy rate in the glucocorticoid group, compared with the control group (OR = 0.62, 95% CI [0.09, 4.32], I 2 = 35%, P = .63) (Fig. 3C).

Discussion
In this review, we compared the effect of glucocorticoid on reproductive outcomes in infertile women with ATA positive and normal thyroid function undergoing ART. The administration of glucocorticoid improved pregnancy rate and live birth rate of women with ATA positive. Only one of the articles concluded that glucocorticoid reduced the abortion rate after in vitro fertilization (IVF) in women with TAI. [19] However, another 2 articles believed that the abortion rate of ATA-positive patients was not influenced by glucocorticoid therapy. Additionally, we found the number of retrieved oocytes varied indistinctively following the glucocorticoid treatment, but the ovarian stimulation response and embryo quality were slightly higher than those in control group. It is probably promising to improve the development and quality of embryos with glucocorticoid supplements. However, few studies have further discussed the treatment strategy, and more relevant studies are needed to address the issue in the future. Several studies emphasized the importance of ATA in many aspects of embryogenesis and embryo implantation. The presence of ATA in ovarian follicles may cause the antibody-mediated cytotoxicity and the damage to the maturing oocyte, then reduce the quality of oocytes and developmental potential. [2,21,22]  Besides, Zhong et al [12] speculated that TPO-Ab may interfere with fertilization and affect embryonic development by binding to the egg and/or embryonic surfaces. Meanwhile, the ATA in the endometrium may obstruct the embryo implantation, resulting in embryonic loss. Vissenberg et al [2] also found that TPO-Ab can diffuse through the placental barrier in late pregnancy. It is well known that controlled ovarian stimulation in IVF can increase the demand for thyroid hormone in patients with TAI, which may change thyroid function and greatly increase the risk of subclinical hypothyroidism. [5,23] Besides, it has been demonstrated that increasing proportion of peripheral blood NK cells (PNK) and cytotoxicity are associated with infertility and IVF failure. [24] Brouillet et al [25] thought the failure of IVF was closely related to the high level of C-reactive protein before embryo implantation. Thus, a growing number of studies suggested that glucocorticoid may regulate the symptoms of thyroid autoimmune disorder, reduce the level of ATA and the number of natural killer cells (NK) which may be helpful for IVF outcomes. Additionally, glucocorticoid is also capable to improve the response of ovary, improve the quality of the embryo, and intrauterine environment through anti-inflammatory and immuno-suppressive treatment. [15,26,27,28] There are still several shortcomings in this study. First, some factors of infertility such as endometriosis, premature ovarian failure are closely related to the presence of ATA, which need stratified research to explore the effect of glucocorticoid treatment. [29] Secondly, the potential interference factors of this study are not clear because the scheme of ART was not unified. One study reported a higher prevalence of ATA in infertile women with 3 or more IVF failures. [30] Another also reported that intracytoplasmic sperm injection (ICSI) could overcome the negative effect of TAI on embryo quality, [21] resulting in a higher implantation rate. Thirdly, the treatment effect of glucocorticoid is not limited to antithyroid antibodies. Other autoantibodies positive, such as antinuclear antibodies and anticardiolipin antibodies, can increase the incidence of repeated IVF-ET failure. [31] Then, due to the strict inclusion and exclusion criteria, the sample size is limited, and the research design is not rigorous enough. Therefore, further researches remain expected to determine the different effects of glucocorticoids on the types and titers of antibodies, the time and dosage of drug usage, as well as the potential complications and risks associated with glucocorticoids.

Conclusion
In conclusion, there was a particular association between thyroid autoantibodies and adverse pregnancy outcomes in ART. We found that glucocorticoid therapy increases pregnancy rate, but does not seem to reduce the risk of miscarriage. Further studies are expected to demonstrate whether glucocorticoid adjuvant therapy is potential to improve reproductive outcomes associated with ATA positive. It is hoped that this meta-analysis can play a positive role in clinical work, so as to remind us to carry out early screening and diagnosis for infertile women with ATA positive, and to better realize the management of patients in ART with thyroid autoimmune diseases for improving pregnancy outcomes.