Objective To analyze the clinical features of differentiated thyroid cancer diagnosed during pregnancy or one year after delivery. Methods A total of 234 women with differentiated thyroid cancer were treated from January 2001 to January 2011.Cases were divided into three groups according to the time of tumor diagnosis( group 1,no pregnancy history; group 2,during pregnancy or in the first year after delivery;group 3,longer than 1 year after the delivery). Results The thyroid nodule was asymptomatic and discovered on routine examination more often in group 2(78.7％ ) than other two groups (P =0.02).There were no significant difference among three groups in age,hospitalization time,operation time,operation method,tumor type,primary tumor stage and mortality. But more patients in group 2 were suffering from extrathyroid invasion ( P =0.024 ),multi-focal cancer ( P =0.023 ),larger cervical lymph node ( P =0.021 ),later regional lymph node stage (P =0.020 ) and higher local recurrence (P =0.001 ).By stepwise logistic regression analysis,pregnancy is one of the factors impacting on local recurrence rate ( P =0.045 ).Conclusions Pregnancy does not affect the mortality of the differentiated thyroid cancer,but the incidence of extrathyroid invasion,multi-focal cancer,cervical lymph node metastasis,local recurrence is higher in patients with differentiated thyroid cancer diagnosed during pregnancy.