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Effect of parity correction on Down syndrome detection by the multiple-marker screening test
K D Wenstrom1, J Owen, L Boots
1Department of Obstetrics and Gynecology, University of Alabama at Birmingham 35233-7333, USA.
American Journal of Obstetrics and Gynecology
|October 1, 1996
Summary
Maternal parity impacts human chorionic gonadotropin levels in Down syndrome screening. Correcting for parity improves detection rates in multiparous women without increasing false positives.
Area of Science:
- Reproductive medicine
- Prenatal diagnostics
- Biochemistry
Background:
- Maternal parity is a factor in prenatal screening.
- Understanding analyte variations is crucial for accurate Down syndrome risk assessment.
Purpose of the Study:
- To investigate the effect of maternal parity on multiple-marker screening analytes for Down syndrome.
- To develop a parity correction factor and evaluate its impact on detection and screen-positive rates.
Main Methods:
- Analyzed 3039 prenatal screening results stratified by maternal parity (0, 1, ≥2).
- Calculated mean multiples of the median for alpha-fetoprotein, estriol, and human chorionic gonadotropin.
- Derived and applied a parity correction factor for human chorionic gonadotropin.
Main Results:
- Human chorionic gonadotropin levels were significantly lower in multiparous women (p=0.0001).
- Parity did not significantly affect alpha-fetoprotein or estriol levels.
- Applying a human chorionic gonadotropin parity correction increased Down syndrome detection from 71% to 82% in women with ≥2 pregnancies, without altering the overall screen-positive rate.
Conclusions:
- Maternal parity significantly influences human chorionic gonadotropin levels.
- Parity correction for human chorionic gonadotropin enhances Down syndrome detection accuracy in multiparous women.
- The proposed correction improves screening efficacy without compromising specificity.