To study the indications of prenatal diagnosis of fetal chromosome karyotype abnormalities, and provide the basis for prenatal diagnosis and clinical genetic counseling.

From October 2010 to April 2014, a total of 5 655 cases of pregnant women who received prenatal diagnosis of fetal karyotype analysis in Prenatal Diagnosis Center, Gansu Provincial Maternity and Child-care Hospital were selected as research subjects. The indications of prenatal diagnosis of the 5 655 cases of pregnant women contained high-risk indications of antenatal serological screening, such as trisomy 21 syndrome risk≥1/270 or trisomy 18 syndrome risk≥1/350 (2 482 cases), age≥35 years old (1 889 cases), adverse pregnancy history (675 cases), chromosomal abnormalities of one of the couple (49 cases), prenatal ultrasound abnormalities (465 cases), and exposure to the poisonous and harmful substance, drugs that may cause teratogenicity and radical line (95 cases). All the indications of prenatal diagnosis were uncrossed. Fetal chromosome karyotype abnormalities were diagnosed by amniocentesis. Different kinds of fetal chromosomes karyotype abnormalities, the number and detection rate, the relationship between fetal chromosome karyotype abnormalities and prenatal ultrasound abnormalities were analyzed by retrospective method. And the fetal chromosomes karyotype abnormalities detection rates of different indications of prenatal diagnosis were analyzed by statistical methods. The study protocol was approved by the Ethical Review Board of Investigation in Gansu Provincial Maternity and Child-care Hospital. Informed consent was obtained from each patient before receiving invasive prenatal diagnosis.

①Among the 5 655 cases of pregnant women who received invasive prenatal diagnosis, 124 cases were detected as fetal chromosomal karyotype abnormalities, and the detection rate was 2.2%. Among 2 482 cases of pregnant women with high-risk indications, 1 889 cases with age≥35 years old, 675 cases with adverse pregnancy history, 49 cases with chromosomal abnormalities of one of the couple, 465 cases with prenatal ultrasound abnormalities, 95 cases with exposure to abnormal substance, 40 cases, 47 cases, 12 cases, 5 cases, 19 cases, and 1 case were detected as fetal chromosomal karyotype abnormalities, respectively. And the the detection rate of fetal chromosomal karyotype abnormalities was 1.6%, 2.5%, 1.8%, 10.2%, 4.1% and 1.1%, respectively. The rate of fetal chromosomal karyotype abnormalities in pregnant women with chromosomal abnormalities of one of the couple or prenatal ultrasound abnormalities was high. There was statistical difference among the fetal chromosomes karyotype abnormalities detection rate of different indications of prenatal diagnosis (χ²=28.23, P<0.001). ②Among the 19 cases of fetal chromosomes karyotype abnormalities with prenatal ultrasound abnormalities, 6 cases were with obvious structural abnormalities, such as heart abnormalities and anasarca, 13 cases were only with soft ultrasound abnormalities, such as ventricular light point, pyelic separation, choroid plexus cysts, single umbilical artery, liver light point, increased thickness of nuchal translucency (NT), polyhydramnios or oligohydramnios, growth index (head circumference, biparietal diameter, length of femur and humerus) abnormalities, nasal bone absence, lateral ventricle normal high value and so on.

It is necessary for pregnant women to receive the fetal chromosomal karyotype analysis if there is malformation or two or more ultrasound soft markers abnormal of fetal ultrasound screening system.