Mosaicism in chorionic villus sampling: an association with poor perinatal outcome.

Prenatal diagnosis by first-trimester chorionic villus sampling was successful in 4319 pregnancies involving 4395 fetuses. Chromosomal mosaicism was present in 55 to 4319 (1.3%). A significant increase in the perinatal loss rate in the placental mosaic group was noted when compared with the nonmosaics: 16.7 versus 2.7%. These findings suggest that placental mosaicism may be a cause of perinatal loss