MIDTRIMESTER FETAL SEX DETERMINATION FROM MATERNAL PERIPHERAL-BLOOD BY FLUORESCENCE IN-SITU HYBRIDIZATION WITHOUT ENRICHMENT OF FETAL CELLS

To determine the fetal sex on 30 women who were 16-20 weeks pregnant, about 100 000 maternal blood nucleated cells were analysed by means of fluorescence in situ hybridization (FISH) with a Y-chromosome-specifi c DNA probe. Cells with the hybridization signal were detected in 12 o f the 30 women. All the 12 mothers gave birth to a male child. Of the other 18 women who had no Y-positive cells in the peripheral blood, 14 gave birth to a female child and four gave birth to a male child. The se false-negative results probably occurred because the number of cell s examined was inadequate. The data obtained in this study suggest tha t fetal sex determination using maternal peripheral blood with FISH is possible and that this diagnostic method will be clinically useful wh en more cells are analysed.