Retrospective analysis of 44 578 pregnancies undergoing non-invasive prenatal testing in Weifang

Objective: To review the results of non-invasive prenatal testing (NIPT) for trisomy 21 (T21), trisomy 18 (T18), trisomy 13 (T13), numerical aberration of sex and other autosomes and copy number variations with a size of >5 Mb.

Methods: NIPT was carried out for 44 578 pregnant women. For those with a high-risk by NIPT, amniotic fluid or cord blood samples were collected for G-banding karyotype analysis, and the pregnancy outcome was followed up.

Results: Among the 44 578 pregnant women, 466 (1.05%) were diagnosed as high risk of T21 (n = 1359), T18 (n = 178) or T13 (n = 129). Among these, 301, 53 and 20 were subjected to prenatal diagnosis by amniocyte or umbilical blood karyotyping analysis, among which 289 were diagnosed as T21, 40 (75.47%) as T18, and 4 (20.00%) as T13. Among the high-risk pregnant women, 2 cases were diagnosed as Down syndrome after birth, while no trisomy 18 and trisomy 13 were recorded. The sensitivity and specificity of NIPT were T21 (99.31%, 99.97%), T18 (100%, 99.97%), T13 (100%, 99.96%), respectively. The positive predictive values for T21, T18 and T13 by NIPT were 96.01%, 75.47% and 20.00%, respectively.

Conclusions: Compared with conventional serological screening and invasive prenatal diagnosis, NIPT has a high sensitivity and specificity for T21, T18 and T13, and has provided an ideal method to screen fetal chromosomal abnormalities.