Cell-Free Fetal DNA Testing: Checking Your Baby's Genetic Health from a Simple Blood Test
Learn how cell-free fetal DNA testing checks your baby's chromosomal health from a simple maternal blood sample.
In short: Cell-free fetal DNA testing extracts the baby’s genetic material from a simple sample of the mother’s blood to check the chromosomes, and can be done after week 10 with high accuracy. It is used when a chromosome problem is suspected, for example with a thick nuchal translucency, an absent nasal bone or older maternal age. An abnormal result is confirmed by chorionic villus sampling or amniocentesis.
- Examination of the fetal genetic material in the mother’s blood during pregnancy
- (cell free fetal DNA testing)
What does it mean to examine the fetal genetic material in the mother’s blood during pregnancy?
This test involves extracting small fragments of the baby’s genetic material (DNA) that circulate naturally in the mother’s blood during pregnancy. It offers a simple, non-invasive way to learn more about your baby’s health without directly touching the womb.
When does the fetus’s genetic material appear in the mother’s blood during pregnancy?
Small amounts of the baby’s DNA appear in the mother’s blood early in pregnancy, but the amount is usually enough for a reliable result from the tenth week of pregnancy, which is when this test is typically done.
What is the purpose of examining the fetal genetic material in the mother’s blood during pregnancy?
The main purpose is to help assess the baby’s chromosomal wellbeing — in other words, to screen for certain chromosomal conditions in a safe, simple way.
In what cases is the fetal genetic material in the mother’s blood examined during pregnancy?
This test can be offered to any pregnant woman who wishes to screen for chromosomal conditions, whatever her age, and it is especially useful for women at higher risk, such as those of advanced maternal age or with a higher-risk result on the first-trimester combined screening. If the ultrasound shows a clear abnormality, such as a markedly increased nuchal translucency, your doctor will usually recommend a diagnostic test (CVS or amniocentesis) instead, because the blood test does not detect all the conditions that can cause these findings.
How accurate is the examination of the fetal genetic material in the mother’s blood during pregnancy?
This test is considered highly reliable as a screening tool: it detects about 99 percent of babies with Down syndrome and a slightly lower proportion of babies with trisomy 18 and trisomy 13, with very few false-positive results. Occasionally the test gives no result (for example when the amount of the baby’s DNA is too low) and may need to be repeated. It’s important to remember that it is a screening test, not a final diagnosis.
What is the appropriate action if there is a suspicion of a chromosomal abnormality by examining the fetal genetic material in the mother’s blood during pregnancy?
If results raise a suspicion of a chromosomal abnormality, the next step is to refer the patient to a maternal and fetal medicine specialist for further diagnostic testing. This may include taking a small sample from the fetal placenta (chorionic villus sampling) to study its cells, or taking a sample of the amniotic fluid surrounding the baby (amniocentesis) for a more definitive diagnosis.
No decision about the pregnancy should ever be made based on the blood test result alone; a high-risk result must first be confirmed by one of these diagnostic tests.
If you have questions about this test or your pregnancy care, the team at Dr. Najeeb Layyous’s clinic is here to guide you through your options with care and clarity.
Dr Najeeb Layyous F.R.C.O.G
Consultant Obstetrician, Gynecologist and Infertility Specialist
The finest doctor in Jordan — may God bless him and his whole medical team. A doctor in every sense of the word. I advise anyone planning a pregnancy to visit Dr. Najeeb Layyous. His manner is wonderful, always smiling, with the highest ethics; he gives every patient her due, and the patient’s comfort matters most to him. We had been to many doctors and none understood and treated my case except him. Special thanks to him and the whole team, and to Dina in particular — a lovely person. I recommend anyone considering IVF or pregnancy to visit his clinic.