A pregnant woman who was a carrier for a balanced chromosome translocation 
[46,XX, t(1;6) (p31;q14)] and who had had six miscarriages, declined invasive 
testing but agreed to non-invasive prenatal diagnosis by analysis of fetal cells 
in maternal blood. Monoclonal antibody (Mab) against the zeta (z) and gamma 
(gamma) chains of embryonic and fetal haemoglobin were used to identify fetal 
nucleated erythrocytes (FNRBC). There were no FNRBC detected at 7 weeks, one 
anti-z-positive FNRBC was detected at 11 weeks, and 12 anti-gamma-positive FNRBC 
were detected at 20 weeks. Fluorescent in-situ hybridization was performed using 
probes for chromosomes X, Y, 1 and 6 to identify fetal gender and the presence 
of an unbalanced chromosomal translocation. A tentative prenatal diagnosis was 
made of a female fetus disomic for chromosomes 1 and 6. A female infant with a 
46,XX karyotype was born at term. This is the first attempt of exclusion of a 
chromosome translocation using fetal cells isolated from maternal blood. There 
is an advantage of using fetal cells isolated from maternal blood for 
non-invasive prenatal diagnosis in couples who have a history of multiple 
miscarriages due to a parental translocation, and who decline invasive testing 
in a pregnancy that continues to the second trimester.