ABSTRACT
OBJECTIVE: To discuss the detectability of NIPT for pregnant women at advanced maternal age (AMA), and mainly focused on how many fetal abnormalities will be missed by NIPT. METHODS: A total of 4194 women at AMA who accepted cytogenetic prenatal diagnosis were recruited in this study. All the AMA women received amniocentesis at 18-23â¯weeks. Combined with our detection level of NIPT and literature reports, we evaluated the detectability of NIPT. RESULTS: After cell karyotype analysis, a total of 233 (5.56%) fetuses were confirmed to have chromosomal abnormalities, including 91.0% were abnormal chromosome number and 9.0% were abnormal chromosome structure. According to the detectability of NIPT we calculated, 87.6% abnormal results could also be detected by NIPT. However, NIPT would miss 12.4% abnormal results which could be originally found by the karyotype analysis of amniotic fluid cells. The major types of missed fetal abnormalities include structural rearrangement, mosaic and triploidy. Meanwhile, there were no relationship between the detectability of NIPT and the age of AMA pregnant women. CONCLUSIONS: About 12.4% of fetal chromosomal abnormalities will be missed if NIPT completely replaces invasive prenatal diagnosis in AMA women. Fortunately, these types of fetal abnormalities missed by NIPT did not increase with the age elevating of pregnant women.
