Chromosomal karyotype analysis for 2948 fetuses in mid-or late pregnancy

Objective To evaluate prenatal diagnosis value of chromosomal karyotypes for fetus of mid-or late pregnary.Methods Chromosomal karyotypes of cells in amniotic fluid or cord blood were analyzed among 2 948 fetuses in 16-36 weeks of pregnancy with signs for prenatal diagnosis.Results Totally 272 cases of abnormal chromosomal karyotypes were identified among the pregnancies with a positive rates of 9.3%.The rate of abnormal autosomal and sex chromosome were 98.8% and 1.2%,respectively.Polymorphism and number abnormality were the most common among the autosomal and sex chromosome.Conclusion The most frequent abnormal chromosomal are chromosomal polymorphism and number abnormality for fetuses with signs for pregnatal diagnosis.Prenatal diagnosis with chromosomal karyotypes analysis is helpful in reducing newborn with abnormal chromosomal karyotypes.