Objective: To evaluate the application of non-invasive prenatal testing (NIPT) in high-risk pregnancies before invasive prenatal diagnosis.
Methods: This prospective study involved all pregnancies participating in the clinical trial of NIPT validation. The indication, age and gestational week were recorded. And the results of karyotype and NIPT risk were compared.
Results: A total of 2 439 high-risk pregnancies were enrolled from 18 prenatal diagnosis clinics in China. After excluding 48 cases (36 missing clinical information, 9 karyotype failures and 3 NIPT failures), 2 391 cases were analyzed. Their gestational ages were 10 to 31 weeks. And 56.3% (1 345/2 691) were at a high risk for mid-trimester screening, following by advanced maternal age (26.0%, 621/2 391). Forty-six aneuploidies (trisomy 21, n = 38; trisomy 18, n = 7; trisomy 13, n = 1) were diagnosed by karyotyping. And it was consistent with the NIPT results of high-risk distribution.
Conclusion: NIPT may be used to reduce unnecessary invasive prenatal diagnosis by improving the efficacy of current mid-trimester screening strategy, particularly for trisomy 21.