Many women who present with desmoid-type fibromatosis (DF) have had a recent pregnancy. Long-term data about disease behavior during and after pregnancy are lacking.

To investigate the possible relationship between DF and pregnancy.

A cohort of women with DF and pregnancy was identified from 4 sarcoma centers. Four groups were identified: diagnosis during pregnancy (A); diagnosis after delivery (B); DF clinically evident during pregnancy (C); and DF resected before pregnancy (D). Progression/regression rates, recurrence rates after resection, and obstetric outcomes were analyzed.

Ninety-two women were included. Forty-four women (48%) had pregnancy-related DF (A + B), whereas 48 (52%) had a history of DF before conception (C + D). Initial treatment was resection in 52%, medical therapy in 4%, and watchful waiting in 43%. Postsurgical relapse rate in A + B was 13%, although progression during watchful waiting was 63%. Relapse/progression in C + D was 42%. After pregnancy, 46% underwent treatment of DF, whereas 54% were managed with watchful waiting. Eventually, only 17% experienced further progression after treatment. Spontaneous regression occurred in 14%. After further pregnancies, only 27% progressed. The only related obstetric event was a cesarean delivery.

Pregnancy-related DF has good outcomes. Progression risk during pregnancy is high, but it can be safely managed. DF does not increase obstetric risk, and it should not be a contraindication to future pregnancy.