Objective  To evaluate the efficiency of maternal serum alpha-fetoprotein (AFP) and free beta human chorionic gonadotrophin (free β-HCG) detection during second-trimester for screening of fetal neural tube defects (NTD).

  Methods  We collected data on 437 438 pregnant women who voluntarily received prenatal screening for fetal birth defects in 5 prenatal diagnosis centers in Hangzhou city during the period from October 2007 through September 2014. We also collected monitoring data on follow-up screening for birth defect reported by maternal and child health care hospitals in all counties or districts of Hangzhou municipality. Risks 2T Prenatal Screening Analyzing Software was adopted to assess NTD risk.

  Results  During the 8-year period, totally 10 anencephalus, 32 rachischisis, and 9 encephalocele cases were diagnosed among the pregnant women at high risk of having a baby with birth defect based on AFP and free β-HCG screening; another 9 anencephalus, 28 rachischisis, and 14 encephalocele cases were ascertained during follow-up surveys among the pregnant women at the low risk. The sensitivity of AFP and free β-HCG prenatal screening were 52.63% (10/19) for anencephalus, 53.33% (32/60) for rachischisis, and 39.13% (9/23) for encephalocele, respectively. The false positive rate of AFP and free β-HCG prenatal screening for anencephalus, rachischisis, and encephalocele were 0.38% (1 676/437 419), 0.38% (1 654/437 378), and 0.38% (1 677/437 415). The detection rate of anencephalus, rachischisis and encephalocele were 0.59%, 1.90%, and 0.53% among the pregnant women at high risk based on AFP and free β-HCG prenatal screening, which were significantly higher than those (0.02‰, 0.07‰, and 0.03‰) among the pregnant women at the low risk (P < 0.001 for all).

  Conclusion  The prenatal screening based on maternal serum AFP and free β-HCG measurement can detect not only Down′s syndrome and trisomy 18 syndrome, but also anencephalus, rachischisis, and encephalocele. Maternal serum AFP and free β-HCG detection combined with other prenatal screening technique and procedures is helpful to reduce the incidence of congenital defects.