Abstract
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.
Highlights
Thyroid autoimmunity (TAI), diagnosed as the presence of thyroid antibody, is the most common autoimmune disorder among women of childbearing age
No significant difference was found in the number of oocytes retrieved (median [interquartile range]: [6,7,8,9,10,11,12] vs. [7,8,9,10,11,12,13], P = 0.091); after adjusting for anti-Müllerian hormone (AMH) levels, basal follicle stimulating hormone (FSH) levels, basal E2 levels, FT4 levels, thyroid-stimulating hormone (TSH) levels, and antral follicle count, the number of oocytes retrieved was significantly lower in patients with thyroid autoimmunity (TAI) than in controls (Regression Coefficient, -0.48; 95%confidence intervals (CIs), -0.06 to -0.90; P=0.025) (Table 3)
The mechanisms underlying the impact of TAI on in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) outcomes from follicular growth to pregnancy remain unclear, but currently, there are two hypotheses
Summary
Thyroid autoimmunity (TAI), diagnosed as the presence of thyroid antibody, is the most common autoimmune disorder among women of childbearing age. Accumulating evidence has demonstrated the association between thyroid antibody and pregnancy outcomes after in vitro fertilization (IVF)/ intracytoplasmic sperm injection (ICSI) treatment, and studies based on the IVF/ICSI process have provided new models to investigate the association between thyroid antibodies and pregnancy outcomes and enabled the analysis of the role of TAI in earlier gestational stages from oocyte fertilization to embryo implantation [1]. In a meta-analysis, including 12 studies, Andrea et al performed a comprehensive analysis on the association between TAI and IVF/ ICSI outcomes [2], and they concluded that the presence of thyroid antibodies exerted detrimental effects on pregnancy outcomes, including an increased risk of miscarriage and a decreased frequency of live birth. The sample sizes in the studies included in this meta-analysis were all small, and the conclusions in those studies were controversial
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