The Prevalence of Thyroid Dysfunction and Autoimmunity in Women With History of Miscarriage or Subfertility

Abstract

Objective To describe the prevalence of and factors associated with different thyroid dysfunction phenotypes in women who are asymptomatic preconception. Design Observational cohort study. Setting A total of 49 hospitals across the United Kingdom between 2011 and 2016. Participants Women aged 16 to 41years with history of miscarriage or subfertility trying for a pregnancy. Methods Prevalences and 95% confidence intervals (CIs) were estimated using the binomial exact method. Multivariate logistic regression analyses were conducted to identify risk factors for thyroid disease. Intervention None. Main Outcome Measure Rates of thyroid dysfunction. Results Thyroid function and thyroid peroxidase antibody (TPOAb) data were available for 19213 and 19237 women, respectively. The prevalence of abnormal thyroid function was 4.8% (95% CI, 4.5-5.1); euthyroidism was defined as levels of thyroid-stimulating hormone (TSH) of 0.44 to 4.50 mIU/L and free thyroxine (fT4) of 10 to 21 pmol/L. Overt hypothyroidism (TSH > 4.50 mIU/L, fT4 < 10 pmol/L) was present in 0.2% of women (95% CI, 0.1-0.3) and overt hyperthyroidism (TSH < 0.44 mIU/L, fT4 > 21 pmol/L) was present in 0.3% (95% CI, 0.2-0.3). The prevalence of subclinical hypothyroidism (SCH) using an upper TSH concentration of 4.50 mIU/L was 2.4% (95% CI, 2.1-2.6). Lowering the upper TSH to 2.50 mIU/L resulted in higher rates of SCH, 19.9% (95% CI, 19.3-20.5). Multiple regression analyses showed increased odds of SCH (TSH > 4.50 mIU/L) with body mass index (BMI) ≥ 35.0 kg/m2 (adjusted odds ratio [aOR] 1.71; 95% CI, 1.13-2.57; P = 0.01) and Asian ethnicity (aOR 1.76; 95% CI, 1.31-2.37; P < 0.001), and increased odds of SCH (TSH ≥ 2.50 mIU/L) with subfertility (aOR 1.16; 95% CI, 1.04-1.29; P = 0.008). TPOAb positivity was prevalent in 9.5% of women (95% CI, 9.1-9.9). Conclusions The prevalence of undiagnosed overt thyroid disease is low. SCH and TPOAb are common, particularly in women with higher BMI or of Asian ethnicity. A TSH cutoff of 2.50 mIU/L to define SCH results in a significant proportion of women potentially requiring levothyroxine treatment.

MANAGEMENT OF ENDOCRINE DISEASE: Thyroid and female infertility: more questions than answers?!

“…The prevalence of thyroid disorders in women aged 20-45 years in Europe varies between 5 and 7% for subclinical hypothyroidism (SCH), 0.2-4.5% for overt hypothyroidism (OH), 0.3-1% for hyperthyroidism and 5-10% for thyroid autoimmunity (TAI) (1,2,3). Differences between countries can be present according to the iodine status, the ethnic backgrounds of the population and the cut-offs used to define SCH (4,5).…”

Functional ovarian reserve in women with infertility and euthyroidism: what is the role of thyroid autoimmunity?

“…Thyroid disease is quite prevalent in women of childbearing age and is associated with menstrual irregularities, anovulation and infertility [1,2]. In Europe that varies between 5-7% for subclinical hypothyroidism, 0.2-4.5% for overt hypothyroidism, 0.3-1% for hyperthyroidism and 5-10% for thyroid autoimmunity [3,4,5].…”

More Live Births in Primary Subfertile Intracytoplasmic Sperm Injection-Treated Women with High Normal TSH Levels

“…The prevalence of these high normal TSH levels in assisted reproductive techniques (ART)-treated women is 4 times higher (20-26%) [3,4] than those in the general population (5%) [5]. The prevalence of thyroid autoimmunity is higher in subfertile women with TSH above 2.5 mIU/L: the probability of having thyroid peroxidase antibodies (TPO-Abs) doubles from slightly under 0.2 with TSH 2.5 mIU/L to slightly above 0.4 with TSH of 4.5 mIU/L [6]. About 8% of women with recurrent miscarriage or subfertility and thyroid autoimmunity developed thyroid dysfunction during pregnancy [6,7].…”

“…The prevalence of thyroid autoimmunity is higher in subfertile women with TSH above 2.5 mIU/L: the probability of having thyroid peroxidase antibodies (TPO-Abs) doubles from slightly under 0.2 with TSH 2.5 mIU/L to slightly above 0.4 with TSH of 4.5 mIU/L [6]. About 8% of women with recurrent miscarriage or subfertility and thyroid autoimmunity developed thyroid dysfunction during pregnancy [6,7]. The area of dialog, by lack of evidence, is reflected in recommendations of both the American Thyroid Association [8] and the American Society for Reproductive Medicine [9], pointing at the possible benefit of levothyroxine supplementation for women undergoing IVF or ICSI with TSH >2.5 mIU/L with or without thyroid autoimmunity, however not recommending screening or treatment with levothyroxine [8].…”