First-trimester screening for trisomy 21 in singleton pregnancies achieved by assisted reproduction

Abstract

Background: The possible effect of assisted reproduction on first-trimester screening for trisomy 21 was examined by fetal nuchal translucency thickness (NT), maternal serum free β-human chorionic gonadotrophin (HCG) and pregnancy-associated plasma protein-A (PAPP-A). Methods: Parameters were measured at 11-14 weeks in 411 singleton pregnancies achieved by controlled ovarian stimulation, including 220 that had undergone IVF. Results were compared with 1233 singleton pregnancies conceived spontaneously. Results: In the IVF pregnancies, the median fetal NT was not significantly different from that in controls, whilst the median free β-HCG was significantly increased, and PAPP-A was significantly decreased. In the intracytoplasmic sperm injection group, fetal NT and free β-HCG values were not significantly different from those in control, but PAPP-A was significantly decreased. In those pregnancies achieved by ovarian stimulation, neither fetal NT, free β-HCG nor PAPP-A were significantly different from the control group. Conclusions: In IVF pregnancies, screening for trisomy 21 by fetal NT, maternal serum free β-HCG and PAPP-A levels may be associated with a 1.2% higher false-positive rate than in natural conception.