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Fetal Cell/DNA Prenatal Gender Test: How It Works

This test uses both fetal cells and fetal DNA isolation from maternal blood. During pregnancy, a variety of cell types of fetal origin, as well as fetal DNA, cross the placenta and circulate within maternal peripheral blood. This fetal material is a source of information about the gender and genetic makeup of the developing fetus. Fetal genetic material can be detected in maternal blood early in gestation.

The rarity of fetal nucleated cells in maternal blood has made their isolation particularly challenging. To obtain quantities sufficient for analysis, the use of enrichment techniques is required. The investigators begin with a 30 ml maternal venous blood sample.

An initial enrichment step facilitates removal of many maternal non-nucleated cells through density gradient centrifugation. Subsequent "purification" of fetal cells is performed by:

  1. efficient magnetic cell separation technology and;
  2. cultivation of fetal progenitor cells.

Fetal Cells*
Click here to enlarge

Fetal cells and DNA are in the mother's blood.

"..fetal DNA is...plentiful in a future mom's bloodstream..."

--Kaiser, Jocelyn (2005) from PRENATAL DIAGNOSIS: An Eariler Look At Baby's Genes

"...fetal DNA [is] present in the maternal circulation and can be recovered for noninvasive prenatal genetic diagnosis."

--Farideh et al. (2002) from Cell-free fetal DNA and intact fetal cells in maternal blood circulation: implications for first and second trimester noninvasive prenatal diagnosis.

View More Scientific Research on Prenatal DNA Testing on Maternal Blood

*Taken with microscope during actual testing


The detection of fetal cells in maternal plasma is much simpler and more robust than the detection of fetal nucleated cells in maternal blood, and does not require prior enrichment. In fact, the concentration of fetal DNA in maternal plasma expressed as a percentage of total DNA has been measured from 0.39% (the lowest concentration measured in early pregnancy), to as high as 11.4% (in late pregnancy).

This approach has been shown to have application in the prenatal diagnosis of fetal rhesus D status, sex-linked disorders, fetal sex determination, and paternally inherited genotyping. In addition to maternal plasma, fetal DNA can also be detected in maternal urine; however, the sensitivity of detection is lower.



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