As described in our previous studies,9 (link),15 (link) all the subjects received prenatal screening in the second trimester after genetic counseling and obtaining their informed consent. Their blood samples were collected between 15 weeks 0 days and 22 weeks 6 days. The levels of α-fetoprotein (AFP) and free β subunit human chorionic gonadotropin (fβhCG) were quantified by time-resolved fluoroimmunoassay (TRFIA) using Wallac 1235 AutoDELFIA (DELFIA1235: Perkin Elmer, Waltham, MA). Combined with maternal age, gestational age, maternal weight, and insulin-dependent diabetes, the risk values were calculated using the Lifecycle software (4.0), including the risk value of neural tube defects (NTD), T21 and T18. High risk: T21 >1/300, T18 >1/350. The intermediate risk was T21 1/300~1/1000, T18 1/350~1/1000.16–18 (link) Women aged ≥35 were considered at an advanced maternal age.
Women with HR results received genetic counseling. Most of them underwent prenatal diagnosis. The pregnant women voluntarily chose traditional karyotype analysis and/or CMA after receiving genetic counselling from the clinicians. Both centers used the same detection platform, experimental scheme, and quality control standards, and participated in the laboratory quality control evaluation plan.
Women with HR results received genetic counseling. Most of them underwent prenatal diagnosis. The pregnant women voluntarily chose traditional karyotype analysis and/or CMA after receiving genetic counselling from the clinicians. Both centers used the same detection platform, experimental scheme, and quality control standards, and participated in the laboratory quality control evaluation plan.
