Abstract:Objective To discuss the value of ultrasonic measurement of fetal nasal bone (NB) and nuchal translucency (NT) thickness during the first trimester of pregnancy and maternal AFP and free-β-HCG detection during the second trimester of pregnancy in identifying Down's syndrome (DS). Methods A total of 2,185 pregnant women in the outpatient and inpatient departments from March 2010 to June 2014 were selected. The NB and the thickness of NT were detected by ultrasound from the 11th to 14th gestational week. The absence of nasal bone was abnormal and NT≥3 mm was designed as high risk. The levels of maternal serum AFP and free-β-HCG were detected from the 15th to 21st gestational week. The risk of DS was assessed by the software of analysis system of DS prenatal screening, and the risk rate ≥1/270 was designed as high risk. Amniotic membrane puncture was performed for chromosome examination of amniotic fluid cells under informed consent. The screening results were compared among group A (NB+NT), group B (NB+maternal serological test) and group C (NB+NT+maternal serological test). Results The incidence of DS in the group C was significantly higher than that of the groups A and B (P < 0.05). Conclusions The joint measurement of NB+NT+maternal serological test can improve the reliability of prenatal screening for DS, and improve the pertinence of invasive amniocentesis.