Presence of cells of fetal origin in maternal circulation of pregnant women.

Fetal cells can be identified by using the polymerase chain reaction to test for the presence of human Y-chromosome-specific ZFY and SRY gene DNA sequences in maternal peripheral blood of women who bear a male fetus. Thirty-one pregnant women were studied in the first trimester to determine when fetal cells become detectable in the maternal circulation. Among the 19 women whose peripheral blood samples were positive for Y-chromosome-specific DNA sequences, the presence of fetal cells was quite case-variable from the 6th to 12th gestational weeks. Twenty-eight women who had given birth to their first male babies were studied postpartum to determine when fetal cells disappear from the maternal circulation. Fetal cells can still be detected in maternal blood 10 months postpartum in some cases. These results suggest that identification of fetal cells in the maternal circulation is possible. Nevertheless, interpretation of fetal cells in maternal circulation should be handled very carefully with respect to when these fetal cells first became detectable and potential interference from previous pregnancies.