Cell-free DNA screening
for twin pregnancies

Presented at the 2020 Society for Maternal Fetal Medicine (SMFM) Annual Meeting.

At inception, the ability to detect aneuploidy in twin pregnancies using cell-free DNA (cfDNA) was rightfully doubted. But there is now increasing data supporting the use of cfDNA screening for twin pregnancies.

Noninvasive prenatal cfDNA screening for chromosomal aneuploidy has been available for twin pregnancies for eight years on several commercial platforms.1,2,3 Here we summarize our clinical laboratory experience in screening twin pregnancies to contribute to the growing body of literature supporting the use of cfDNA technology for twin gestations.

We examined twin pregnancy outcomes following testing performed using the Innatal Prenatal Screen (n=1,477) to assess performance in twin pregnancies.

What did we find?

  • Of 1,477 twin gestations, 96.5% received a negative result (n=1425) and 0.7% received a positive result (n=10)4
  • Of the 1,477 cases, there was one reported false positive result, giving an observed false positive rate of 0.07%4
  • No false negative cases were reported4
The Innatal Prenatal Screen performs well for twins
(similar performance to singleton pregnancies),
supporting continued use for screening twin gestations.
This research was presented at the 2020 Society for Maternal-Fetal Medicine (SMFM) Annual Meeting. Download the poster


  1. Fosler et al. Clinical laboratory experience with noninvasive prenatal testing in twin gestations. Poster presented at the Society for Maternal Fetal Medicine; 2015; San Diego, CA.
  2. Roche. 2018. Cell-Free DNA Screening in Twin Pregnancies using the Harmony® Prenatal Test. Roche Diagnostics Australia.
  3. Norwitz et al. Validation of a Single-Nucleotide Polymorphism-Based Non-Invasive Prenatal Test in Twin Gestations: Determination of Zygosity, Individual Fetal Sex, and Fetal Aneuploidy. J Clin Med 2019, 9, 937.
  4. Niemchak et al. Noninvasive prenatal screening for fetal aneuploidy in twin pregnancies: A clinical laboratory experience. Poster presented at SMFM 2020. Grapevine, TX.