Introduction In Belarus, Thyroid cancer (TC) is the 4th most common cancer site among female population with incidence 15,7 per 100 000 (all ages) and the 2nd among women of reproductive age (15–49 years).

Objectives The study aimed to evaluate the potential of pregnancy prolongation during TC.

Methods This prospective case-control study was performed from January 2011 to December 2017. The study included 3 groups. Group A - pregnant women with TC, Group B - patients diagnosed with TC (control), and group C - healthy pregnant women (comparison).

Results 450 patients were enrolled: group A and B had the same number of patients – 188. Group C - 74 patients. The median age for group A, B, C were 31,05 ±4,8, 31,44±5,6, 30,62±5,3 respectively, p>0,05. 114 patients (60,64%) TC was diagnosed before pregnancy and 74 patients (39,36%) during pregnancy in group A. There were no significant differences in stage between group A and B. The major part of patients were diagnosed with stage I (94,1% and 97,3%, p>0.05) in both group. The median follow-up was 75 and 60 months, respectively. Overall survival (OS) rate was 100% for both groups. Progression-free survival rate (PFS) was 94,4±1,7%, and 97,9±1,1% respectively, p>0.05. We didn’t find statistically significant changes in comparison of pregnancy and childbirth complications in all groups. We didn’t find statistically significant changes in comparison of pregnancy and childbirth complications.

Conclusion Pregnancy and childbirth monitoring, prediction, and correction of revealed complications in patients with TC allow to minimize the number of maternal and perinatal complications.