Endocrine Abstracts

Introduction: Thyroid autoimmunity has been associated with pregnancy loss. A possible mechanism is an overactive maternal immune system leading to rejection of the fetal allograft. In women with recurrent pregnancy losses (RPL), we investigated the association of thyroid peroxidase antibodies (TPOAbs) with number of losses and outcome of first pregnancy after referral.

Methods: Prospective study of women with RPL (≥3) followed at the RPL Unit, Copenhagen University Hospital, from 2011 to 2016. Upon first visit, all women were screened for TSH (Roche Modular E170 electrochemiluminescense immunoassays) and TPOAbs (automated Kryptor immunoflourescent assay). TPOAb-positivity >60 kU/l. We performed test for trends by chi-square or independent t-tests as appropriate, and adjusted regression analyses with covariates: maternal age, TSH (logtransformed), number of losses, immunotherapy, thyroxine replacement therapy. The National Data Protection Agency approved the project.

Results: We included 5219 pregnancies (76.6% spontaneous) in 900 women; 119 (13.2%) women were TPOAb-positive. TPOAb-positivity was neither associated with number of losses (P=0.87, aOR 0.004 (-0.3-0.3), P=0.98), nor number of pregnancies (P=0.62, aOR 1.02 (0.92-1-11) P=0.76). Among TPOAb-positive women, TPOAb-concentration was not associated with number of losses (B=0.75 (-0.12-0.27), P=0.45). In women with a registered first pregnancy after referral, TPOAb-positivity (72 of 557 (12.9%)) was not associated with live birth rate (54.4 vs 60.6%, P=0.35, aOR 0.78 (0.42-1.43) P=0.38). However, live birth rate was significantly associated with total number of losses (aOR 0.53 (0.45-0.61) P=0.000). TSH-levels were positively associated with TPOAb-positivity (P=0.00), but not with any investigated outcome. Immunoglobulin therapy or thyroxine replacement did not alter results.

Conclusion: In a large cohort of women with RPL, we found no association between TPOAbs and pregnancy outcome. TSH-levels were significantly increased in TPOAb-positive women and screening according to guidelines should be performed. However, if RPL is caused by an immunological reaction, thyroid autoimmunity does not seem to be a sensitive marker hereof.