Prenatal diagnostic strategies in the context of increasing maternal age: a retrospective analysis of chromosome karyotypes from 3,700 amniotic fluid samples

Research Question To explore prenatal diagnostic strategies in the context of increasing maternal age.Design The percentage of advanced maternal age (AMA) pregnancies in the Luohe region of China from 2019-2023 was calculated. The prenatal diagnostic indications, abnormal amniotic fluid karyotypes, and pregnancy outcomes of 3681 pregnant women (3700 amniotic fluid samples) were determined. The rates of abnormal amniotic fluid karyotypes for different indications and termination of pregnancy (TOP) rates in pregnant women with different types of fatal chromosomal abnormalities were compared. Results From 2019 to 2023, the proportion of pregnant women of AMA in the Luohe region increased from 11.30% to 16.03%. The most common prenatal diagnosis was AMA (54.50%), followed by abnormal maternal serum screening (35.83%). Among the 3700 amniotic fluid samples, 97 presented numerical abnormalities, 32 presented structural abnormalities, and 2 presented both numerical and structural abnormalities. The TOP rates were highest for numerical and structural abnormalities, followed by numerical abnormalities and structural abnormalities. Among numerical abnormalities, sex chromosome aneuploidies had a lower TOP rate than common trisomies and rare autosomal aneuploidies. Conclusions AMA pregnancies have become the primary prenatal diagnostic indication. In addition to noninvasive prenatal testing (NIPT), amniotic fluid karyotype analysis can also detect mosaicism, structural abnormalities, and triploidy. The combination of karyotype analysis and molecular detection has increased the positive detection rate of chromosomal abnormalities. However, NIPT cannot completely replace amniocentesis.