Pre-Conceptional Anti-Thyroid Antibodies and Thyroid Function in Association with Natural Conception Rates

Abstract

Thyroid functioning is an integral part of the endocrine system that supports conception and pregnancy. Frequent consumption of seafood and iodine by Japanese people may adversely affect their thyroid function. Thus, in this study, we aimed to analyze the associations between iodine intake, thyroid hormones, autoimmunity, and natural conception rates in Japanese women trying to conceive their first child. A prospective study of 24 weeks targeted 80 women with no history of infertility, who did not plan to undergo fertility treatment. Concentrations of urinary iodine concentration and thyroid biomarkers in the serum at enrollment were measured. Thirty-five women naturally conceived during the follow-up. The median (inter-quartile range) urinary concentration of iodine was 297 (165, 500) μg/L. Free triiodothyronine (T3) and free thyroxin (T4) negatively correlated with urinary iodine concentrations. Women with anti-thyroid peroxidase (anti-TPO) ≥ 16 IU/mL had lower conception rates (hazard ratio: 0.28, 95% confidence interval, 0.08–0.92) compared with those with anti-TPO < 16 IU/mL, after adjusting for age and coital frequency. None of anti-thyroglobulin antibody, free T3, free T4, or thyroid-stimulating hormone showed significant associations with conception rate after adjusting for age and coital frequency. The negative association between thyroid autoimmunity and natural conception rates warrants further investigation.

The Thyroid Hormone Axis and Female Reproduction

“…Similarly, TPOAbs, but not TSH, were correlated with lower live birth rates and higher miscarriage rates in a study of 1468 infertile women [ 157 ]. In the same way, a more recent study of women without infertility found a negative association between TPOAbs levels and natural conception rates [ 158 ]. Investigating the impact of TSH levels versus those of autoimmunity, d’Assunção et al identified no differences in pregnancy rates among infertile women with AITD undergoing IVF when comparing ‘low’ vs. ‘high’ TSH (<2.5 vs. >2.5 mU/L) [ 159 ], suggesting that autoimmune destruction rather than reduced serum TSH links thyroid and reproductive pathologies.…”

Positive Thyroid Peroxidase Antibody among Women with Polycystic Ovarian Syndrome Visiting an Infertility Clinic at a Tertiary Care Centre

“…Higher autoantibody levels in these patients might as well be the culprit behind insufficient response to infertility treatment. 13 , 14 Mounting evidence suggests that inflammation and autoimmunity can cause PCOS. 12 Likewise, a higher prevalence of autoimmunity with PCOS might cause an increased risk of metabolic syndrome, infertility issues and adverse pregnancy outcomes.…”