ObjectiveTo determine the infant and early childhood developmental outcome associated with choroid plexus cysts diagnosed prenatally.MethodsBetween January 1990 and August 1995, 8270 women underwent second-trimester ultrasound examinations. All women whose fetuses were diagnosed as having choroid plexus cyst(s) underwent ultrasonographic detailed anatomy survey, were offered fetal karyotyping, and were followed with serial ultrasounds. Fetal karyotype, associated structural anomalies, maternal serum triple analyte screen, neonatal outcomes, and infant and early childhood developmental milestones were recorded. The children were followed subsequently, and developmental assessment was performed with a modified Denver II Developmental Screening Test.ResultsA diagnosis of choroid plexus cyst was made in 89 fetuses (1.1%). The mean (± standard deviation [SD]) gestational age at diagnosis was 18.2 ± 1.9 weeks (range 15–22). The cysts varied in size and laterality, with a mean (±SD) size of 5.9 ± 3.3 mm (range 1–23). Three of the 61 women who underwent testing for fetal karyotype (4.9%) had abnormal karyotypes identified. All three karyotypes were trisomy 18, and all three trisomy 18 fetuses had additional sonographic abnormalities. All 28 women who chose not to undergo fetal karyotypic analysis delivered phenotypically normal infants. Infant and childhood developmental follow-up was performed on 76 children with cysts diagnosed prenatally. The mean (±SD) length of childhood follow-up was 35.5 ± 16.2 months (range 12–82). All 76 children were found to be developmentally normal by the Denver II Developmental Screening Test.ConclusionThese observations suggest that the finding of isolated choroid plexus cysts is not associated with delayed infant and early childhood development or an increased risk of abnormal karyotype. The presence of isolated choroid plexus cysts does not warrant intensive infant and early childhood follow-up.