[Application of chromosomal microarray analysis in prenatal diagnosis of pregnant women with advanced age]

To assess the value of chromosomal microarray analysis (CMA) for the detection of fetal anomalies among pregnant women with advanced age.

CMA results of 562 cases, in addition with the outcome of pregnancy and neonatal follow-up were reviewed.

Among the 562 amniotic fluid samples, 73 cases (12.99%) of fetal chromosomal abnormalities were detected, which included 21 cases (3.73%) of chromosomal aneuploidies and 52 cases (9.25%) of copy number variations (CNVs). The latters included 27 cases of pathological CNVs (4.80%), 4 cases of possible pathogenic CNVs (0.71%) and 42 cases of variants with unknown clinical significance (7.47%). Compared with those under 35, the detection rate of fetal chromosomal aneuploidies for women with advanced age was higher under the indications of voluntary test, abnormal ultrasonic structures, abnormal ultrasonic soft index and risks indicated by non-invasive prenatal testing (NIPT). No significant difference was found in the detection rate of CNVs between those ≥35 and <35 and between those with age factor only and with additional indications (P> 0.05). 552 cases (98.22%) of pregnant women have completed the followed up. Among 31 women with pathological and possible pathogenic fetal CNVs detected by CMA, 25 had terminated the pregnancy, 6 (19.35%) have delivered without obvious abnormality. 41 pregnant women with fetal CNVs of unknown clinical significance have completed the follow up, among whom 3 had terminated the pregnancy, 1 newborn was found with malformation after birth, which yielded an abnormal pregnancy rate of 9.76%. 480 pregnant women with negative CMA results have completed the follow up, among whom 5 (1.04%) had abnormal pregnancy or delivered a child with birth defect.

There is a certain difference between the outcome of pregnancy predicted by CMA testing and the actual outcome. The pregnancies with fetal CNVs with unknown clinical significance detected by CMA have a high adverse rate, which should attract clinical attention. CMA testing should be recommended for pregnant women with advanced age regardless of whether they have other symptoms. CMA combined with other detection methods is the trend for prenatal diagnosis.