From Which Week Can NIPT Be Performed?

Non-invasive prenatal testing (NIPT) is a screening test that analyses placental cell-free DNA circulating in the pregnant patient’s blood. NIPT can generally be performed from 10 weeks of pregnancy. Because it uses a maternal blood sample, it does not require entry into the uterus as chorionic villus sampling (CVS) or amniocentesis does.

Timing matters. Earlier in pregnancy, the proportion of placental DNA in the blood—known as the fetal fraction—may be too low for a reliable analysis. This can lead to a “no result” report and the need to consider another sample or a different assessment.

Why is NIPT usually started at 10 weeks?

The amount of placental cell-free DNA in maternal blood generally rises as pregnancy progresses. Current clinical guidance supports cell-free DNA screening from 10 weeks. The precise time should still be chosen after confirming gestational age by ultrasound and considering multiple pregnancy, the selected panel and the patient’s medical history.

Fasting is usually not required, although the sample collection instructions of the laboratory should be followed. Accurate information about gestational age, multiple pregnancy and relevant recent medical procedures should be provided.

What does NIPT assess?

NIPT primarily estimates the chance of common chromosome-number conditions such as trisomy 21 (Down syndrome), trisomy 18 and trisomy 13. Depending on the panel, certain sex chromosome differences may also be screened. Test scope varies between laboratories.

NIPT does not screen for every genetic condition and it is not a diagnostic test. A low-risk result reduces the estimated chance of the conditions examined but does not eliminate it. A high-risk result does not prove that the fetus is affected.

What happens after a high-risk or no-result report?

A high-risk result should be reviewed with clinical findings and genetic counselling. Depending on gestational age, CVS or amniocentesis may be offered for diagnostic confirmation. Irreversible decisions should not be based on a screening result alone.

A no-result or low-fetal-fraction report is not the same as a normal or abnormal result. Gestational age, sample quality and maternal biological factors can affect the analysis. The clinician may discuss repeat sampling, detailed ultrasound or diagnostic testing according to the individual situation.

Other important prenatal time windows

10–13 weeks: First-trimester combined screening and nuchal translucency ultrasound may be performed.
10–13 weeks: CVS may be used for diagnostic sampling when indicated.
15–20 weeks: Amniocentesis is usually performed during this period.
18–22 weeks: A detailed fetal anatomy ultrasound is performed; NIPT does not replace this examination.