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

✍ Scribed by Kevin Spencer; Charas Y. T. Ong; Adolfo W. J. Liao; Demetres Papademetriou; Kypros H. Nicolaides

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 54 KB
• Volume: 20
• Category: Article
• ISSN: 0197-3851
• DOI: 10.1002/1097-0223(200008)20:8<673::aid-pd880>3.0.co;2-5

✦ Synopsis

In a study of 2923 normal pregnancies and 203 pregnancies affected by trisomy 21 we have shown a signi®cant difference in the median MoM of the markers: fetal nuchal translucency, maternal serum free b-hCG and PAPP-A in the presence of a female fetus compared with a male fetus. For maternal serum free b-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.