Objective      To identify the relationship between prenatal diagnosis indications and abnormal karyotype in mid/late-duration of pregnancy

and investigate the necessity of invasive prenatal diagnosis for high risk gravida.       Methods      A total of 4 808 high-risk pregnant women at age from 19 to 42 with a mean age 30.5 were recruited in our genetic consultant department between August 2006 and April 2011. Fetal umbilical vein blood or amniotic fluid were derived by amniocentesis and then used for cell culture and karyotype analysis. Fluorescent in situ hybridization (FISH) was conducted to evaluate the accuracy of the karyotype analysis. Fetal ultrasonic inspection and follow-up visit of pregnancy outcome were also carried out.       Results      Of the153 chromosomal abnormalities

there were 102 with numerical abnormalities of autosome

including 73 cases of trisomy 21 syndrome (2 cases of the syndrome are one from twins)

22 cases of trisomy 18 syndrome

4 cases of trisomy 13 syndrome

1 case of trisomy 18 syndrome and 1 case of triploid. There were 27 cases with structural abnormalities of autosome

15 cases with numerical abnormalities of sex chromosome and 9 cases of chimeras. Prenatal diagnosis indications included abnormal color-ultrasonogram

advanced age

high risk for Down syndrome

dys-pregnancy history

high value of NT and balanced chromosome translocation carrier. Of all the chromosomal abnormalities cases above

23 chose to continue pregnancy and 130 choose to terminate pregnancy.       Conclusion      In the prenatal diagnosis indications of mid/late-duration of pregnancy

abnormal color-ultrasonogram

advanced age and high risk for Down syndrome are closely related to the occurrence of fetus chromosomal abnormalities. In this group of high-risk pregnant women

there are 69.28% fetuses with chromosomal abnormalities. So for the couple who have fetus with chromosomal abnormality

they should make a decision according to the percentage of chromosomal abnormalities

genetic rules

and their breeding status if they want to keep the baby.