Clinical evaluation of NIPS for women at advanced maternal age: a multicenter retrospective study

Objective: To explore the clinical effect of noninvasive prenatal screening (NIPS) for the women at advanced maternal age (AMA) and discuss the relationship between women's age and NIPS effect.Methods: Fourteen thousand thirty-five women at AMA who accepted NIPS from two prenatal diagnosis centers were recruited for this study. NIPS were checked by Illumina Next CN 500. All the AMA women received prenatal genetic counseling, selected prenatal diagnosis and different clinical treatments according to the results of NIPS.Results: A total of 114 cases (0.81%) got the NIPS-positive results of T21/T18/T13. One hundred four cases of them accepted prenatal diagnosis and 87 cases were proved as true positive. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 100, 99.88, 92.55 and 100%, respectively. Seventy-four women (0.53%) showed NIPS-positive results of sex chromosomal aneuploidies (SCAs). After informed consent, 46 women (62.2%) accepted fetus karyotype analysis. Nineteen cases were identified as true positive results, while 27 cases were false positive results. The PPV for SCAs in AMA women was 41.3%. The PPV of T21/T18/T13 in AMA women over 40 was 100%, while it was 81.91% for the women whose age was 35 ∼ 40 years old. There was also rising trend in PPV of fetal sex chromosome with the increased age (62.50 versus 36.84%).Conclusions: NIPS is a good choice for AMA pregnant women. It can not only achieve satisfactory clinical effect, but also greatly reduce invasive prenatal diagnosis. We will get better effect of NIPS by further managing AMA women stratified by their age.