SUMMARY OBJECTIVE: This study aimed to assess the perinatal outcomes of pregnancies with a prenatal diagnosis of congenital cystic adenomatoid malformation. METHODS: We conducted a retrospective cohort study based on information contained in the medical records of pregnant women whose fetuses had been prenatally diagnosed with congenital cystic adenomatoid malformation by ultrasonography. RESULTS: Sample analysis was based on 21 singleton pregnancies with confirmed isolated fetal congenital cystic adenomatoid malformations. The mean maternal±standard deviation age was 28±7.7 years. Types I, II, and III congenital cystic adenomatoid malformation were detected in 19% (4/21), 52.4% (11/21), and 28.6% (6/21), respectively. All fetuses presented with unilateral congenital cystic adenomatoid malformation (21/21) without associated anomalies, and 52.3% (11/21) were in the right lung. In total, 33.3% (7/21) of fetuses presented a “congenital cystic adenomatoid malformation volume ratio” >1.6 and were managed with maternal betamethasone administration. The mean gestational age at the time of steroid administration was 28.5±0.9 weeks, with a reduction in the lesion dimensions of 9.5% (2/21) (Types I and III of congenital cystic adenomatoid malformation). The mean gestational age at delivery was 38.7±2.4 weeks, and a cesarean section was performed in 76.2% (16/21) cases. Postsurgical resection was necessary for 23.8% (5/21) of the patients, and 4.7% (1/21) of them died because of respiratory complications after surgery. Pulmonary hypoplasia occurred in 9.5% (2/21) of the patients, and 4.7% (1/21) of them died because of respiratory insufficiency. The survival rate was 90.5% (19/21), and 57.2% (12/21) remained asymptomatic. CONCLUSION: Despite the isolated prenatal diagnosis of congenital cystic adenomatoid malformation, which showed good survival, congenital cystic adenomatoid malformation is associated with significant perinatal morbidity. Maternal betamethasone administration did not significantly reduce fetal lung lesion dimensions.