title: The influence of maternal weight on human chorionic gonadotropin in the multiple-marker screening test for fetal Down syndrome.
abstract: OBJECTIVE
  Our purpose was to determine the effect of maternal weight on human chorionic gonadotropin concentration in the multiple-marker screening test for fetal Down syndrome.
  
  
  METHODS
  Two genetics databases were used: database I contained the results of 8297 multiple-marker screening tests and database II contained the results of 1936 multiple-marker screening tests and fetal karyotypes.
  
  
  RESULTS
  The overall screen-positive rate in database I was 7.1%; it was 7.5% in patients weighing < 180 pounds and 5.1% in patients weighing > or = 180 pounds (p = 0.001). Weight significantly affected the screen-positive rate only in women > or = 30 years old (p = 0.003 for 30 to 34 years, p = 0.00004 for > or = 35 years). A weight correction formula was derived; when applied to database II it eliminated individual weight-related differences but had no effect on the overall screen-positive rate or Down syndrome detection rate.
  
  
  CONCLUSIONS
  Human chorionic gonadotropin concentration is affected by maternal weight. A weight correction formula eliminates individual weight-related differences in the screen-positive rate but has no discernible effect on the overall screen-positive or Down syndrome detection rates.
mesh_terms: D000328:Adult; D000367:Age Factors; D015415:Biomarkers / Q000097:blood; D001835:Body Weight; D006063:Chorionic Gonadotropin / Q000097:blood*; D004314:Down Syndrome / Q000175:diagnosis*; D004964:Estriol / Q000097:blood; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis*; D006801:Humans; D007256:Information Systems; D008423:Maternal Age; D011247:Pregnancy; D018566:Pregnancy, High-Risk; D011296:Prenatal Diagnosis; D011446:Prospective Studies; D012189:Retrospective Studies; D000509:alpha-Fetoproteins / Q000378:metabolism
chemical_list: D015415:Biomarkers; D006063:Chorionic Gonadotropin; D000509:alpha-Fetoproteins; D004964:Estriol