['Pregnancy may be associated with an increased risk of recurrence /progression of differentiated thyroid cancer (DTC). However, it is unclear if the impact of pregnancy would differ based on pre-pregnancy response to therapy status. Our objective was to investigate the risk of recurrence /progression of DTC applying the response to therapy assessments to pre-pregnancy status as recommended by the 2015 ATA thyroid cancer guidelines.', 'This is a retrospective review of 235 women followed at Memorial Sloan Kettering Cancer Center (MSKCC) for DTC and who had a term pregnancy after initial treatment for DTC between 1997 and 2015.', 'Structural disease recurrence /progression after pregnancy was documented in 5% (11/235) of the patients. When evaluated 3-12 months after delivery, patients who had an excellent, indeterminate or biochemical incomplete response pre-pregnancy continued to show no evidence of structurally identifiable disease. Conversely, in women with structural incomplete response to therapy prior to pregnancy, structural progression (defined as ≥3mm increase in the size of known disease or identification of new metastatic foci) was identified after delivery in 29% (11/38). However, additional therapy was recommended during the first post-partum years in only 8% (3/38) of those patients that had a structural incomplete response to therapy prior to pregnancy while the remainder (92%) continued to be followed with observation.'] Is response to therapy status an excellent predictor of pregnancy-associated structural disease progression in patients previously treated for differentiated thyroid cancer?