Salomea Guchmazashvili1, Maia Kereselidze2, Tinatin Manjavidze2, Nino Chkhaberidze2 1University of Georgia School of Health Sciences, Tbilisi, Georgia; 2Department of Medical Statistics, National Center for Disease Control and Public Health, University of Georgia School of Health Sciences, Tbilisi, Georgia Correspondence: Salomea Guchmazashvili (saloguchmazashvili@gmail.com)

Thyroid Research 2025, 18(1):PO15

Background and Objectives: Thyroid cancer is a significant public health concern worldwide, with its incidence steadily increasing over the past few decades. The relationship between thyroid cancer and the risk of spontaneous abortion (miscarriage) in women is complex and influenced by various factors, including thyroid function, treatment modalities, and the presence of thyroid autoantibodies.

This study aims to evaluate the prevalence of spontaneous abortions among women with and without thyroid cancer and among women with different treatment types.

Methods: A retrospective cohort study used data from the Georgian Cancer and Birth Registries (2016–2023). The study population included 108 women with thyroid cancer (C73) and 6,990 women without thyroid cancer or other chronic conditions who experienced miscarriages. The study assessed the distribution of spontaneous abortions by maternal age in both groups.

Additionally, among 108 women with thyroid cancer who had a history of miscarriage, the study examined the distribution of spontaneous abortions by the type of cancer treatment (radioactive iodine therapy or surgery) and the interval from treatment to subsequent pregnancy. The categorization of time intervals was based on international guidelines and findings from prior studies and tailored according to treatment modality, reflecting clinical recommendations regarding optimal waiting periods before conception.

Statistical analysis – the chi-square test was conducted using SPSS to analyze differences in abortion type distribution between the groups.

Results: 47% of women with thyroid cancer experienced spontaneous abortions, vs 31% in women without thyroid cancer.

The age distribution analysis showed that among women without cancer, the highest proportion of abortions (29%) occurred in the 35–39 age group, whereas in women with thyroid cancer, the highest proportion (33%) was observed in the 30–34 age group (p < 0.05) and the difference was statistically significant.

Among women with thyroid cancer and a history of spontaneous abortion, 69% had undergone surgical treatment prior to pregnancy, while 20% had received radioiodine therapy. Among those with a history of surgical treatment, the highest proportion of spontaneous abortions (47%) occurred when conception took place within 12–60 months after surgery. Among women with a history of radioiodine therapy, 69% of spontaneous abortions occurred when the interval between treatment and pregnancy was longer than 12 months.

Conclusions: This study identified a significantly higher rate of spontaneous abortions among women with a history of thyroid cancer compared to women without cancer. The age distribution of abortion outcomes differed between the two groups, with younger age groups more affected among women with thyroid cancer. Notably, there was a difference between treatment types and timing by spontaneous abortion.

These findings underscore the importance of enhanced preconception counseling and management of thyroid hormone levels before and during pregnancy

Further prospective studies are needed to investigate the effectiveness of monitoring and optimization of thyroid hormone levels, particularly in the case of total thyroidectomy, which requires lifelong hormone replacement in order to inform evidence-based reproductive counseling and improve maternal and fetal health outcomes.