The influence of fetal sex in screening for trisomy 21 by fetal nuchal translucency, maternal serum free beta-hCG and PAPP-A at 10-14 weeks of gestation.
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 beta-hCG and PAPP-A in the presence of a female fetus compared with a male fetus. For maternal serum free beta-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.
Spencer
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K
Endocrine Unit, Clinical Biochemistry Department, Harold Wood Hospital, Gubbins Lane, Romford, Essex, RM3 0BE, UK. Kevin_Spencer@Compuserve.com
Ong
C Y
CY
Liao
A W
AW
Papademetriou
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D
Nicolaides
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KH
D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005260:Female; D005865:Gestational Age; D006801:Humans; D008297:Male; D009333:Neck / Q000000981:diagnostic imaging / Q000196:embryology*; D011247:Pregnancy; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis*; D011296:Prenatal Diagnosis; D012737:Sex Factors; D016216:Ultrasonography, Prenatal
D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A