What is fetal fraction percentage?

Fetal fraction percentage is a measurement used in non-invasive prenatal testing (NIPT) to determine the amount of fetal DNA present in a mother's blood sample. The fetal fraction percentage is typically expressed as a decimal or a percentage and represents the proportion of DNA in the mother's blood that comes from the fetus.

A higher fetal fraction percentage is associated with a more accurate and reliable NIPT result, as it indicates a greater amount of fetal DNA present in the sample. A low fetal fraction percentage may lead to inconclusive results or a higher risk of false positives or false negatives.

Factors that can affect the fetal fraction percentage include the gestational age of the pregnancy, the mother's weight, the presence of maternal conditions such as obesity or autoimmune disorders, and technical aspects of the NIPT process.

It is important for healthcare providers to take the fetal fraction percentage into consideration when interpreting NIPT results and discussing them with patients.