Second-trimester unconjugated oestriol levels in maternal serum from chromosomally abnormal pregnancies using an optimized assay

Prenat Diagn. 1993 Apr;13(4):271-80. doi: 10.1002/pd.1970130406.


Second-trimester unconjugated oestriol (UE3) levels were measured retrospectively in maternal serum from 78 chromosomally abnormal pregnancies and 390 matched controls using a radioimmunoassay kit (Amersham AMERLEX-M) optimized for use in the second trimester. Reduced levels of UE3 were found in a group of 49 Down's syndrome pregnancies with a median UE3 level of 0.79 multiples of the median (MOM) of the controls. Four trisomy 18 pregnancies had UE3 levels less than 0.7 MOM. There was a highly significant level of correlation between alpha-fetoprotein (AFP) and UE3 levels in the controls (r = 0.25, p < 0.01), the Down's syndrome pregnancies (r = 0.44, p < 0.01), and the other chromosome abnormalities (r = 0.61, p < 0.01). When used as an additional marker to AFP and human chorionic gonadotrophin in screening for Down's syndrome, UE3 does not appear to add to the sensitivity of such screening.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromosome Aberrations / blood*
  • Chromosome Disorders
  • Chromosomes, Human, Pair 18
  • Down Syndrome / blood
  • Estriol / blood*
  • Female
  • Humans
  • Pregnancy / blood*
  • Pregnancy Trimester, Second
  • Radioimmunoassay
  • Retrospective Studies
  • Trisomy
  • alpha-Fetoproteins / analysis


  • alpha-Fetoproteins
  • Estriol