To analyze the application value of different prenatal diagnosis indications of fetal Down syndrome (DS) in the prenatal diagnosis during the second trimester.

From 1st January 2011 to 31st December 2014, clinical data of 18 693 cases of pregnant women who received amniocentesis in Maternal and Child Hospital/Children′s Hospital/Obstetrics and Gynecology Hospital of Guangxi Zhuang Autonomous Region were selected as research subjects. The prenatal diagnosis indications of DS among 18 693 cases of pregnant women who received amniocentesis during the second trimester included: advanced maternal age (≥35 years old, 11 664 cases), high risk of serum screening (the risk value of trisomy-21 syndrome ≥ 1/270, trisomy-18 syndrome ≥ 1/350, 4 226 cases), abnormal fetal ultrasound examination results (620 cases), one of the couple with chromosomal abnormalities (651 cases), and one of the couple or two with mediterranean anemia (782 cases), abnormal pregnancy history (748 cases) and noninvasive prenatal test (NIPT) positive (2 cases). All the prenatal diagnosis indications of DS were uncrossed. Amniotic fluid cells were collected by amniocentesis to take the genetics examination, in order to final diagnose the fetal DS. The number and detection rate of fetal DS among pregnant women during the second trimester with the above-mentioned prenatal diagnosis indications of DS were compared, and the detection rate of fetal DS was analyzed by statistical method. The study protocol was approved by the Ethical Review Board of Investigation in Maternal and Child Hospital/Children′s Hospital/Obstetrics and Gynecology Hospital of Guangxi Zhuang Autonomous Region. Informed consent was obtained from each participate before receiving amniocentesis.

A total of 18 693 cases of amniotic fluid were detected, and 151 cases were detected as fetal DS, the detection rate was 0.8% (151/18 693). The results of amniocentesis showed that, among 11 664 cases of pregnant women with advanced maternal age, 4 226 cases with high risk of serum screening, 620 cases with abnormal fetal ultrasound examination results, 651 cases with one of the couple with chromosomal abnormalities, 782 cases with one of the couple or two with mediterranean anemia, 748 cases with abnormal pregnancy history and 2 cases with NIPT positive, 45, 79, 15, 2, 5, 3 and 2 cases were detected as fetal DS, respectively. And the detection rate of fetal DS was 0.4%, 1.9%, 2.4%, 0.3%, 0.6%, 0.4% and 100.0%, respectively. There was statistical difference among the fetal DS detection rate of different prenatal diagnosis indications of fetal DS (χ²=111.83, P<0.001).

High-risk of serum screening, advanced maternal age (≥35 years old), and abnormal ultrasonic testing results are important prenatal diagnosis indications of fetal DS. At the same time, we should pay attention to the prenatal diagnosis indications of one of the couple with chromosomal abnormalities or mediterranean anemia, in order to reduce the rate of birth defects.