Preconceptual thyroid peroxidase antibody positivity in women with recurrent pregnancy losses may contribute to an increased risk for another miscarriage

• Published in: Clinical endocrinology (Oxford) 2023-02, Vol.98 (2), p.259-269
• Main Authors: Blomqvist, Lennart, Nyström, Helena F., Hellgren, Margareta, Strandell, Annika
• Format: Article
• Language: English
• Subjects: 1st trimester; Abortion; Abortion, Spontaneous; Acetylsalicylic acid; association; Autoantibodies; autoimmunity; biochemical pregnancy; delivery; disease; early pregnancy; Endocrinology & Metabolism; Endocrinology and Diabetes; Endokrinologi och diabetes; Female; First; guidelines; Humans; Iodide Peroxidase; levothyroxine; Miscarriage; Prediction models; Pregnancy; Pregnancy Trimester; Pregnancy Trimester, First; recurrent; recurrent miscarriage; Risk factors; Spontaneous; subclinical hypothyroidism; Thyroid; Thyroid gland; thyroid peroxidase antibodies; Thyroid-stimulating hormone; Thyrotropin; thyroxine
• ISSN: 0300-0664; 1365-2265; 1365-2265
• DOI: 10.1111/cen.14825

Objective To investigate preconceptual thyroid peroxidase antibody (TPO‐ab) positivity and/or thyroid stimulating hormone (TSH) levels in the upper range of normal as risk factors for recurrent unexplained first‐trimester miscarriage. Design A post‐hoc study of a randomized trial, in which acetylsalicylic acid did not affect the risk of a new miscarriage. Patients Women (n = 483) with at least three unexplained recurrent first‐trimester miscarriages investigated at a Swedish secondary referral center. Measurements The levels of TPO‐ab and TSH were determined before pregnancy. The occurrence of a new first‐trimester miscarriage was analyzed by logistic regression with adjustments when applicable, for age, number of previous miscarriages, obesity and the investigated covariates levels of TPO‐ab and TSH. Results Including all first trimester miscarriages, odds ratio (OR) according to presence of TPO‐ab was 1.60 (95% confidence interval [CI]; 0.99–2.57), after adjustment 1.54 (95% CI; 0.94–2.53). Very early (biochemical) pregnancy losses occurred more often in women with than without preconceptual TPO‐ab (6.8% vs. 2.0%), OR 3.51 (95% CI; 1.15–10.71), after adjustment 2.91 (95% CI; 0.91–9.29). There was no association between TSH in the upper range of normal and a new miscarriage, adjusted OR 0.76 (95% CI; 0.32–1.83). A prediction model for a new miscarriage included number of previous miscarriages, woman's age and presence of TPO‐ab. Conclusion In women with at least three recurrent unexplained pregnancy losses, the presence of TPO‐ab may contribute to an increased risk of a first‐trimester miscarriage, possibly more pronounced in very early pregnancy. TSH levels 2.5–4.0 mU/L do not seem to increase the miscarriage risk. Summary Thyroid peroxidase antibody antibodies may contribute to an increased risk for a new miscarriage in women with unexplained recurrent pregnancy loss, especially very early in the first trimester, but thyroid stimulating hormone in the upper range of normal does not.