Maternal serum free α-human chorionic gonadotrophin levels in twin pregnancies: Implications for screening for Down's syndrome

1994 ◽  
Vol 14 (8) ◽  
pp. 717-719 ◽  
Author(s):  
N. J. Wald ◽  
J. W. Densem
Keyword(s):  
Down's Syndrome ◽  
Down’S Syndrome ◽  
Maternal Serum ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Serum Free ◽  
Twin Pregnancies

Temporal Changes in Maternal Serum Biochemical Markers of Trisomy 21 across the First and Second Trimester of Pregnancy

2002 ◽  
Vol 39 (6) ◽  
pp. 567-576 ◽  
Author(s):  
K Spencer ◽  
JA Crossley ◽  
DA Aitken ◽  
ABJ Nix ◽  
FDJ Dunstan ◽  
...  
Keyword(s):  
Weighted Least Squares ◽  
Down's Syndrome ◽  
Protein A ◽  
Down’S Syndrome ◽  
Maternal Serum ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Least Squares Regression ◽  
Concentration Changes ◽  
Β Hcg

Background Many maternal serum markers show concentration changes in Down's syndrome pregnancies but the magnitude of the change in median marker levels varies with gestation. To date these changes have not been accurately specified. Methods The trends in marker median levels between 6 and 20 weeks of gestation were examined for alphafetoprotein (AFP), free β human chorionic gonadotrophin (F β-hCG), total human chorionic gonadotrophin (ThCG) and pregnancy-associated plasma protein A (PAPP-A) by a meta-analysis of data obtained from our collaborative studies and routine screening programmes for Down's syndrome over a 10-year period. Data were available from between 709 and 1082 Down's syndrome pregnancies and from between 14 607 and 153 909 unaffected pregnancies for each marker. The median multiple of the median (MoM) and mean log10MoM for each marker at each completed week of gestation were estimated and the trend with gestation smoothed using a weighted least squares regression model. Results The gestational ages at which maximum separation of marker levels occurred, comparing affected and unaffected pregnancies, and the respective regressed median MoMs and mean log10MoMs, were: for AFP at 16 weeks, 0·72 MoM, 0·14288 log10MoM; for F β-hCG at 15 weeks, 2·24 MoM, 0·35034 log10MoM; for ThCG at 16 weeks, 1·93 MoM, 0·28548 log10MoM, as well as before 8 weeks (< 0·65 MoM, 0·18853 log10MoM); and for PAPP-A before 8 weeks, < 0·33 MoM, 0·47727 log10MoM. Conclusion There is significant temporal variation in mean log10MoM values for the screening markers investigated. Screening algorithms, modified to take account of this variation, should allow more accurate gestation-specific risks to be calculated in individual pregnancies.

scholarly journals Assessment of Atypicality: An Adjunct to Prenatal Screening for Down's Syndrome That Facilitates Detection of other Abnormalities

1993 ◽  
Vol 30 (6) ◽  
pp. 578-583 ◽  
Author(s):  
D E Wright ◽  
T M Reynolds ◽  
C M Donovan
Keyword(s):  
Prenatal Screening ◽  
Down's Syndrome ◽  
Down’S Syndrome ◽  
Maternal Serum ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Low Risk ◽  
Risk Estimates ◽  
Risk Reporting

Current software used for assessment of the risk of Down's syndrome may give misleading risk estimates if applied to other abnormalities. Often the abnormality is reflected in maternal serum α-fetoprotein and human chorionic gonadotrophin levels and is then translated into a low risk for Down's syndrome that may not be recognized as significantly atypical of normality. We regard this as a serious deficiency in the current Down's syndrome risk reporting algorithm, and suggest a modification that allows the problem to be overcome.

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