Non-invasive prenatal paternity testing has brought a transformative change in regard to how parents who are expecting can establish biological connections during the pregnancy phase. This is a non-invasive testing procedure that requires a simple blood sample from the mother to examine fetal DNA. The success of such testing, however, is greatly dependent on a factor known as fetal fraction, the extent of baby DNA in the mother's blood. Fetal fraction is a concept that everyone has to understand before deciding to do early paternity testing when pregnant.
What is the concept of fetal fraction, and why is it very crucial in early non-invasive prenatal paternity testing (NIPPT)?
Fetal fraction is described as a fraction of cell-free DNA in the maternal blood that belongs to the baby and not to the mother. Small quantities of the baby's DNA during pregnancy flow in the bloodstream of the mother. In prenatal paternity testing, this fetal fraction should have a minimum to get accurate results. When the fraction of the fetus is too small, the baby's DNA is not sufficient to analyse. Laboratories should have enough fetal DNA in order to differentiate between the genetic markers of the baby and the mother. The majority of the reliable NIPP testing is dependent on a fetal fraction of at least 4 per cent to give reliable paternity results, although laboratories would prefer a higher overall percentage in order to give better results.
What is the technique of measuring fetal fraction during an NIPPT test?
Fetal fraction is measured when a blood sample of the mother is analyzed in the laboratory. Once the blood is drawn, the lab technicians get all the cell-free fetal DNA that floats within the bloodstream of the mother. This DNA is then analyzed using special equipment to identify the percentage that is provided by the baby and the mother. The test examines particular genetic markers that have the ability to differentiate fetal DNA and maternal DNA. DNA fragments are then counted, and the ratio is calculated using advanced sequencing technology. This percentage of fetuses in prenatal paternity testing measurement is automatic and occurs during the normal process of the test. In the event that fetal fraction is less than the necessary limit, the laboratory usually reports to the client that the sample cannot be used and may possibly advise reexamination at some later gestational age, where the fetal fraction in prenatal paternity testing will increase naturally.
What effect do maternal factors and gestation age have on the level of fetal fraction?
The level of fetal DNA in the blood of the mother is influenced by a number of factors. By being familiar with these influences, it is easier to understand why reliable NIPP test[1] can be more effective in specific periods or among specific individuals:
Pregnancy gains fetal fraction with gestational age, with a higher level achieved beyond 9-10 weeks.
Female weight has a negative influence on fetal fraction because more body weight reduces the concentration of fetal DNA.
Fetal fraction measurement and analysis by twins are quite complicated due to multiple pregnancies.
Mothers with health issues, including some autoimmune diseases, can affect the levels of DNA.
Past pregnancies may offer some leftover fetal DNA that interferes with the current measurements.
Placental health has a direct influence on the quantity of fetal DNA that is released to maternal circulation.
The maternal age could be of a slight influence on the fetal fraction in some instances.
IVF conceptions typically are viewed as having varying patterns of fetal fractions compared to natural conceptions.
The level of cell-free DNA in blood can be affected by the use of heparin and some medications.
It is important to note that medical experts affirm that the fetal fraction in prenatal paternity testing continues to rise with the progression of the pregnancy, and a few more weeks will enhance the success rate of the test.
When should a non-invasive prenatal paternity test be conducted?
Prenatal paternity testing is also sometimes conducted in a non-invasive manner and may commence about 7-8 weeks into pregnancy, although most testing centres prescribe waiting till 9-10 weeks of pregnancy for optimal outcomes. Fetal fraction values are typically high and good enough at these early gestational ages to produce accurate analysis. But success rates are greater in the case of 10 weeks when the fetal fraction in prenatal paternity testing is greater. It does not need any complicated tests or actions to be performed, merely a blood sample of the mother and a DNA sample of the possible father, often a cheek swab. Premature testing performed before 7 weeks has not been recommended as the probability of good fetal concentration could be less than satisfactory to be analyzed. Laboratories such as FaceDNATest.com provide non-invasive paternity testing at the prenatal stage and could advise a person on the most appropriate timing, depending on the various situations.
Conclusion
The successful non-invasive prenatal paternity testing is based on fetal fraction. In the absence of sufficient DNA of the fetus in the blood of the mother, the laboratories are not able to effectively undergo genetic testing to ascertain the paternity. This is the reason why timing is prenatal testing is of such importance. Whereas the technology is high-end and safe, it remains reliant on the natural biological functions, which differ by individuals and require going through them during pregnancy, which can be done with a professional point of view by facilities such as Face DNA Testing. The collaboration with skilled testing providers guarantees the collection of samples at the right time and their analysis with the latest scientific techniques.
References:
[1] https://facednatest.com/services/non-invasive-prenatal-dna-testing/
