Non-invasive Prenatal Testing for Assessing Fetal Sex Chromosome Aneuploidy: A Retrospective Study of 45773 Cases

Abstract Objective: To assess the positive predictive value (PPV) of non-invasive prenatal testing (NIPT) as a screening test for sex chromosome aneuploidy (SCA) with different maternal characteristics and prenatal decision in positive cases. Materials and Methods: We retrospectively analyzed 45773 singleton pregnancies with different characteristics that were subjected to NIPT in Maternity and Child Health Hospital of Anhui Province. The results were validated by karyotyping. Clinical data, diagnostic results, and pregnancy outcomes were collected.Results: A total of 314 cases were SCA positive by NIPT; among those, 143 underwent invasive prenatal diagnostic testing, and 58 resulted as true-positive. Overall, the PPV for 45,X, 47,XXX, 47,XXY and 47,XYY was 12.5%, 51.72%, 66.67% and 83.33%, respectively. Interestingly, when screening only pregnant women in advanced maternal age (AMA), the PPV for 45,X, 47,XXX, 47,XXY and 47,XYY was 23.81%, 53.33%, 78.95%, and 66.67%, respectively. AMA was a high-risk predictor of having a fetus with SCA. The frequencies of 47, XXX, and 47,XXY were significantly correlated with maternal age.Conclusion: NIPT performed better in predicting sex chromosome trisomies than monosomy X, and patients with 45,X positive fetus were more eager to terminate pregnancy compared to those with 47,XXX and 47, XYY. Our findings may assist in genetic counseling of AMA pregnant women. Our Pre- and post-test counseling are essential for familiarizing pregnant women with the benefits and limitations of the NIPT, which may ease their anxiety and provide them with the informed choice for further diagnosis and pregnancy decision.