Performance of noninvasive prenatal screening in twin pregnancies: a retrospective study of 5469 twin pregnancies

Abstract

Objectives

To evaluate the performance of noninvasive prenatal screening (NIPS) for the fetal common aneuploidy screening in twin pregnancies.

Methods

The data of 5469 women with twin pregnancies were collected in this retrospective observational study between January 2017 and December 2018. Patients underwent NIPS as first-line screening or after standard serum screening for fetal aneuploidy. The performance of NIPS was examined, and a regression analysis was performed to investigate testing failure in cases of low fetal fraction.

Results

In this study, 2231 (40.8%) patients opted for NIPS as the primary prenatal screening test, and 3238 (59.2%) opted for serum screening, including 440 patients who opted for NIPS after serum screening. Among the 2671 pregnancies with available NIPS outcomes, 11 cases of aneuploidy were identified, seven of trisomy 21 and four of sex chromosome aneuploidy (SCA). The sensitivity and specificity for trisomy 21 were 100% (95% CI, 56.1–100.0%) and 100% (95% CI, 99.8–100.0%), respectively. The positive predictive value (PPV) for SCA was 40.0% (95% CI, 13.7–72.6%). No false negatives were found, with a negative predictive value (NPV) of 100% (95% CI, 99.8–100.0%) in total. In 32 pregnancies who failed NIPS test without available NIPS outcomes due to low fetal fraction, the regression analysis demonstrated that increasing BMI and assisted reproductive technology treatment were significant independent predictors.

Conclusions

NIPS is a high-performing routine primary prenatal screening test in twin pregnancies, with a high PPV and low false positive rate for detecting trisomy 21. It is also useful to identify common sex chromosome aneuploidies in twin pregnancies, with similar performance to that reported in singleton pregnancy.

Keywords:

• Noninvasive prenatal screening (NIPS)
• cell-free DNA
• twin pregnancy
• chromosome aneuploidies
• clinical performance

Acknowledgements

The authors thank the pregnant women and family members who participated in this research program.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was jointly funded by grants from the Research Project of Health and Family Planning Commission of Sichuan Province [No. 20PJ073], the Fundamental Research Funds for the Central Universities [SCU2019C4005], and the Key Research and Development Program of Science and Technology Department of Sichuan Province [2019YFS0420].