Maternal serum screening for chromosome defects: human chorionic gonadotropin versus its free-beta subunit

Fetal Diagn Ther. 1993 Jul-Aug;8(4):221-4. doi: 10.1159/000263830.


The addition of maternal serum intact hCG (MShCG) to routine maternal serum alpha-fetoprotein screening for Down's syndrome is expected to yield a detection efficiency around 60% for an amniocentesis rate approximating 5%. We compared the detection rate using intact MShCG and free-beta hCG in 480 normal pregnancies and 48 with chromosome defects (Down's syndrome 31, other chromosome defects 17). No significant difference in detection efficiency was determined. However, since the false-positive rate with free-beta hCG was almost twice that found with intact hCG, and the detection rate for other chromosome defects was more than double, the intact MShCG assay is currently preferred. Free-beta hCG earlier in gestation may, however, ultimately prove superior in maternal screening for chromosome defects.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Chorionic Gonadotropin / blood*
  • Chorionic Gonadotropin, beta Subunit, Human
  • Chromosome Aberrations*
  • Down Syndrome / diagnosis*
  • False Positive Reactions
  • Female
  • Humans
  • Peptide Fragments / blood*
  • Pregnancy
  • Prenatal Diagnosis*
  • alpha-Fetoproteins / analysis


  • Chorionic Gonadotropin
  • Chorionic Gonadotropin, beta Subunit, Human
  • Peptide Fragments
  • alpha-Fetoproteins