Analysis of the results of non-invasive prenatal testing (NIPT) in 545 pregnant women in advanced maternal age

- OBJECTIVE: This research aimed to explore the value of non-invasive prenatal testing (NIPT) as a prenatal screening method for common aneuploidy in pregnant women in advanced maternal age.PATIENTS AND METHODS: A retrospective analysis was conducted on a cohort of 545 mothers with singleton pregnancy who were of advanced age and underwent NIPT testing voluntarily at the Second Affiliated Hospital of Guangxi Medical University between November 2020 and February 2023. In cases where NIPT testing suggested chromosomal abnormalities, amniocentesis was conducted, karyotype analysis or gene copy number variation (CNV) testing was performed, and the pregnancy outcome was tracked.RESULTS: Among 545 pregnant women in advanced maternal age, 11 cases had high risk of NIPT, and the detection rate was 2.02%. Among 11 pregnant women deemed to be at high risk for NIPT, 10 cases underwent amniotic fluid puncture, and one case refused amniocentesis despite a suggestive chromosomal abnormality in NIPT. The overall rate of amniocentesis was 1.83%. Among 11 pregnant women deemed to be at high risk for NIPT, the results suggested that 5 of them had trisomy 21, 1 had trisomy 18, 2 had sex chromosome abnormalities (specifically, 47, XYY), and 3 had other autosomal abnormalities. The positive predictive values of NIPT were 100.00% for the cases of trisomy 21 and trisomy 18, while the values were 0.00% for the cases of sex chromosome abnormalities and other autosomal abnormalities, respectively. After the follow-up, each of the 6 cases that were diagnosed with definite chromosomal abnormalities during prenatal screening opted to induce labor and terminate the pregnancy, including 5 cases that exhibited a high risk of trisomy 21 (47, XN,+21) and 1 case that showed a high risk of trisomy 18 (47, XN,+18). One instance of NIPT indi cated a potential abnormality in the sex chromosomes, the individual declined to undergo amniocentesis. Another instance of NIPT suggested a sex chromosome abnormality, amniocentesis revealed a deletion of 0.72 Mb in the 4q22.1 region. They all had normal pregnancies and normal newborns. The remaining three cases had normal prenatal diagnoses (46, XN) and experienced normal pregnancies with healthy neonatal outcomes.CONCLUSIONS: NIPT has demonstrated its efficacy as a screening tool in the face of increasing maternal age. As a result, it can substantially decrease the requirement for invasive prenatal diagnosis. Nonetheless, there are instances of erroneous positive outcomes in NIPT testing, and therefore, interventional prenatal diagnosis remains necessary for individuals with high-risk screening outcomes to prevent false positives or unwarranted labor induction.