Positive NIPT result

By trimester

Weeks 1–13

1st trimester

After a first-trimester positive result, genetics counseling can review the chromosome involved, the report's positive predictive value, ultrasound findings, and whether CVS at 10 to 13 weeks or later amniocentesis better answers the question.

Weeks 14–27

2nd trimester

Amniocentesis is commonly available at 15 to 20 weeks and samples amniotic fluid containing fetal cells. A detailed anatomic ultrasound remains important because NIPT does not assess every structural or genetic condition.

Weeks 28–birth

3rd trimester

A positive result discovered later still warrants genetics and maternal-fetal medicine review. The useful next test depends on gestational age, ultrasound findings, the chromosome reported, and which information would change pregnancy or newborn planning.

What does the evidence show for positive NIPT result?

• The 2025 SMFM guideline, endorsed by ACOG, calls cell-free DNA the most sensitive and specific screening option for common trisomies but explicitly states that it is not diagnostic and recommends confirmatory testing after a positive result. 1
• Cell-free DNA in maternal blood is largely placental in origin. Confined placental mosaicism, a demised twin, maternal chromosome variation, and technical factors can produce discordant results, so pregnancy decisions based only on NIPT are not recommended. 1
• MedlinePlus explains that a positive prenatal cell-free DNA result indicates increased risk rather than certainty. CVS and amniocentesis are diagnostic options used to confirm or rule out the chromosome condition reported by screening. 2
• In a prospective cohort of 20,194 screened pregnancies with genetic confirmation for 17,851, positive predictive values differed by trisomy and baseline-risk group even though sensitivity and specificity were similar. A positive result therefore needs condition-specific interpretation, not one universal percentage. 3
• MedlinePlus distinguishes diagnostic sampling from screening and describes the usual timing: CVS can be performed at 10 to 13 weeks, while amniocentesis is usually performed at 15 to 20 weeks. Each test has a small procedure risk and a defined test scope. 4

When should I call my provider about positive NIPT result?

A positive NIPT is not itself a physical emergency, but contact the prenatal team promptly rather than waiting for a distant routine visit. Diagnostic choices are time-sensitive because CVS is generally performed at 10 to 13 weeks and amniocentesis at 15 to 20 weeks. Do not make an irreversible pregnancy decision from screening alone. None of these lists replace your own judgment: if this symptom worries you, that on its own is enough reason to check in with your healthcare provider.