5 Key Takeaways

• 1

  Noninvasive prenatal testing screens for fetal genetic abnormalities from maternal blood from about 10 weeks’ gestation, but positive results require invasive confirmation.

• 2

  The review identifies low fetal fraction, difficulty distinguishing fetal from maternal DNA, and differences between placental and fetal genotypes as key limitations.

• 3

  Most circulating cell-free fetal DNA is about 143 base pairs long, but circular, ultrashort, and much longer fragments have also been identified.

• 4

  The mechanisms by which cell-free fetal DNA enters and circulates in maternal blood remain unresolved, and direct evidence for release in apoptotic extracellular vesicles is lacking.

• 5

  The authors call for research on DNA origin and particle association, which could inform fetal DNA enrichment methods and support more reliable diagnostic applications.