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The influence of fetal sex in screening for trisomy 21 by fetal nuchal translucency, maternal serum free β‐hCG and PAPP‐A at 10–14 weeks of gestation
Author(s) -
Spencer Kevin,
Ong Charas Y. T.,
Liao Adolfo W. J.,
Papademetriou Demetres,
Nicolaides Kypros H.
Publication year - 2000
Publication title -
prenatal diagnosis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.956
H-Index - 97
eISSN - 1097-0223
pISSN - 0197-3851
DOI - 10.1002/1097-0223(200008)20:8<673::aid-pd880>3.0.co;2-5
Subject(s) - trisomy , fetus , aneuploidy , obstetrics , gestation , medicine , gynecology , pregnancy , biology , chromosome , genetics , gene
Abstract In a study of 2923 normal pregnancies and 203 pregnancies affected by trisomy 21 we have shown a significant difference in the median MoM of the markers: fetal nuchal translucency, maternal serum free β‐hCG and PAPP‐A in the presence of a female fetus compared with a male fetus. For maternal serum free β‐hCG levels are higher by 15% if the fetus is chromosomally normal and by 11% if the fetus has trisomy 21. For maternal serum PAPP‐A the levels in chromosomally normal fetuses are 10% higher in the presence of a female fetus and 13% higher if the fetus has trisomy 21. In contrast, fetal nuchal translucency is 3–4% lower in both chromosomally normal and trisomy 21 female fetuses. The consequence of such changes when screening for trisomy 21 will be a reduction in the detection rate in female fetuses by a factor of 1–2%. Correction of risk algorithms for fetal sex, however, is probably not feasible, since ultrasound detection of fetal sex is only 70–90% accurate in the 10–14 week period. Copyright © 2000 John Wiley & Sons, Ltd.