Clinical application of NIPT and expansion of its scope

  Background  Noninvasive prenatal test (NIPT) based on fetal cell-free DNA (cf-DNA) is currently the most accurate prenatal screening for fetal common chromosomal aneuploidies. Pregnant women with different indications for prenatal diagnosis vary in risk of fetal chromosomal abnormalities. It can reduce prenatal diagnostic procedures if we select pregnant women with relatively low risk of fetal chromosomal abnormalities for NIPT, and avoid false negative results of NIPT.

  Objective  To explore candidates suitable for NIPT in pregnant women undergoing invasive prenatal diagnosis and evaluate its clinical application.

  Methods  Totally 1 261 pregnant women who had undergone prenatal diagnostic procedure in the First Medical Center of Chinese PLA General Hospital from January 16, 2018 to June 31, 2020 were selected in our study. All participants had undergone NIPT. Related risk characteristic of fetal chromosomal abnormalities was analyzed by multiple logistic regression analysis. Positive rate and demand for prenatal diagnosis were calculated separately when NIPT was applied in pregnant women with different risk factors.

  Results  A total of 1 261 pregnant women with an average age of (34.65 ± 5.02) years were included in the analysis. The positive rate of invasive prenatal diagnosis was 6.90%. The overall specificity of NIPT was 97.61% (1 146/1 174), negative predictive value was 97.20% (1 146/1 179), and diagnostic accuracy was 95.16% (1 200/1 261). Multivariate logistic regression analysis showed that in this population, there was statistically significant correlation between advanced age (OR=0.470, P=0.010), abnormal ultrasound (OR=2.939, P＜0.001) with fetal chromosomal abnormalities, while there was no statistically significant correlation between abnormal serological screening (OR=0.075), adverse maternal history with family history (OR=0.492). NIPT could reduce the demand for prenatal diagnosis by 42.19% and increase the positive rate of prenatal diagnosis to 11.11%.

  Conclusion  Among pregnant women undergoing invasive prenatal diagnosis, the risk of fetal chromosomal abnormalities in pregnant women with advanced maternal age is lower than the average risk in this population. Remarkable decline and higher proportion of fetal chromosomal anomalies in invasive procedure can be achieved when NIPT is applied in pregnant women with advanced maternal age.