To analyze the chromosomal karyotypes of fetus, and discuss the detection rates of chromosomal abnormalities under different indications for prenatal diagnosis.

Cytogenetic prenatal diagnosis were performed on a cohort of pregnant women with different indications in the second- or third-trimester. Detection rates of fetal chromosomal abnormalities under each indication were compared.

The success rate of amniotic fluid cell culture was 95.1% (562/591), and 33 cases of abnormal karyotypes were found. The detection rate of abnormality was 5.9% (33/562), including 15 cases of triploid syndromes (45.4%), 8 cases of Down′s syndrome, 4 cases of 18-trisomy, and 1 case of 16-trisomy syndrome. The detection rate of abnormal karyotypes was 50% in the pregnant women who or which couple was a carrier of constitutional chromosome abnormality, 10% of the fetuses with abnormal ultrasound founding, 5.6% of pregnant women elder than 35 years old, and 2.6% in high risk pregnancy by serum prenatal screening.

A carrier of chromosomal abnormality of one of the couple, fetal abnormalities found by ultrasound, elder maternal age, and a high risk result by serum prenatal screening are the most important genetic indications for prenatal diagnosis.