NIPT Test Timing: The Week 10 Rule and Fetal Fraction
The Week 10 Rule: Why is it Important?
The most common question: "When is the best time for NIPT?" The answer is directly related to how the test works. NIPT analyzes fetal DNA particles that transfer from the placenta to the mother's bloodstream.
Fetal Fraction: The Heart of the Test
For NIPT to succeed, the fetal DNA ratio (fetal fraction) in maternal blood must reach a certain level — at least 4%. This typically happens by completing week 10 of pregnancy.
What Happens If Done Before Week 10?
Fetal DNA may be insufficient, resulting in an "inadequate sample" (No Call) report. This doesn't mean the baby is sick, but it causes unnecessary stress and delay.
Can Be Done Anytime After Week 10
NIPT can be done from week 10 until birth. As pregnancy progresses, fetal DNA increases, reducing the risk of insufficient samples.
Factors Affecting Timing
- Maternal weight: High BMI may lower fetal DNA ratio.
- Blood thinners: May affect DNA isolation.
- Twin pregnancies: Waiting until week 11 is recommended.
Omega Çare is There at Week 10
When you complete week 10, Omega Çare nurses come to your home, and the sample is analyzed at Omega Genetik.