To grasp the situation of chromosome abnormalities of pregnant women with high-risk in noninvasive prenatal testing (NIPT) in Inner Mongolia Autonomous Region and the application of NIPT in this region.

From March 2013 to July 2017, a total of 82 pregnant women with high-risk in NIPT and then received amniocentesis in the Affiliate Hospital of Inner Mongolia Medical University were collected as research subjects. They were divided into indication group (n=68) and non-indication group (n=14) according to whether they were combined with prenatal diagnosis indications of amniocentesis or not before receiving NIPT. Retrospective analysis was conducted to collect clinical data of these 82 pregnant women, including origin areas of pregnant women, prenatal diagnosis indications of amniocentesis before receiving NIPT, fetal chromosomes abnormalities diagnosed by NIPT and amniocentesis, and statistical analysis was performed. Chi-square test was used to compare the detection rates of fetal chromosome abnormalities between two groups. The study protocol was approved by the Ethical Review Board of Investigation in Human Being of Affiliate Hospital of Inner Mongolia Medical University. Informed consent was obtained from each participant before amniocentesis. There were no statistical differences between two groups in the aspects of age, gestational age, and so on (P>0.05).

①Among 82 pregnant women with high-risk in NIPT in this study, 78.0% (64/82) of them were from three major cities in the Inner Mongolia Autonomous Region which were Hohhot (58.5%, 48/82), Ordos (11.0%, 9/82), and Baotou City (8.5%, 7/82). ②Among those 82 pregnant women with high-risk in NIPT in this study, 82.9% (68/82) pregnant women were combined with prenatal diagnosis indications of amniocentesis before receiving NIPT, including advanced age (≥35 years old) (36.6%, 30/82), high risk in maternal serum screening (30.5%, 25/82), abnormal results of prenatal ultrasonography (15.8%, 13/82); and 17.1% (14/82) of them were not combined with prenatal diagnosis indications of amniocentesis before receiving NIPT. ③Among those 82 pregnant women with high-risk in NIPT in this study, a total of 52 cases of fetal chromosomes abnormalities were detected by amniocentesis, and the detection rate of fetal chromosome abnormalities was 63.4% (52/82). The detection rate of NIPT for fetal autosomes abnormalities (21-, 18-, and 13-trisomy) was 85.7% (36/42), and the detection rate of NIPT for fetal sex chromosome abnormalities was 45.7% (16/35). ④The detection rate of fetal chromosome abnormalities in indication group was 73.5% (50/68), which was significantly higher than that in non-indication group 14.3% (2/14), and the difference was statistically significant (χ²=17.563, P<0.001).

The application of NIPT technology in Inner Mongolia Autonomous Region has improved the deficiency of prenatal aneuploid screening in this region. However, there is still a lack of consensus in clinical practice so far in the indications of NIPT screening. And the false positive rate of NIPT screening for chromosomal abnormalities in our hospital is significantly higher than that in other regions. In addition, using the prenatal screening methods common in current clinical trials for initial prenatal screening could effectively improve the positive detection rate of NIPT.