Antenatal sex determination in blood from pregnant women.

Reported results concern Y-chromatin of lymphocytes and granulocytes in the peripheral blood of pregnant women. In women who later delivered male children, a mean of 3.75% Y-chromatin was found in lymphocytes. Even after investigation of paternal Y-chromatin, the rate of false diagnoses (14%) in prenatal sex diagnosis could be reduced only moderately. In early pregnancy lymphoid cells with a Y-chromatin could be first traced only in the 8th week; granulocytes showing a Y-chromatin did not appear until the 9th week.