[Re-evaluation of indications for prenatal diagnosis of advanced pregnant women under the new screening regime].

Objective: To assess the value of non-invasive prenatal testing (NIPT) for women with advanced gestational age but normal measurement for nuchal translucency (NT).

Methods: A total of 9371 singleton pregnancies with negative NT screening at early pregnancy were reviewed. Among these, 8627 cases were selected to be screened again by NIPT, and their indications and results were analyzed. The results were compared with those of with other high risk factors and young gestational age.

Results: The incidence of fetal aneuploidies increased in women with advanced gestational age and ultrasound soft markers, in particular among those who were negative for NT screening but over the age of 37. The detection rate of pathological or likely pathological copy number variations was 1.88% among women who directly underwent invasive prenatal diagnosis because of the advanced age, but there was no correlation with the increase of age. 0.68% of the women where with negative NT screening and NIPT still need to undergo invasive prenatal diagnosis.

Conclusion: After NT screening in early pregnancy, NIPT can replace invasive prenatal diagnosis for those below the age of 37, though there is still a possibility of missed detection of pathogenic copy number variation. It is necessary to strengthen ultrasonic monitoring in later period.