Stepwise sequential screening for trisomy 21 in assisted reproduction pregnancies.

We offered a modified stepwise sequential integrated screening for Down syndrome to 72 singleton and 16 twin pregnancies obtained with assisted reproductive techniques, observing no cases of trisomy 21 and obtaining a false positive rate of 10% in singleton and 7% in twin pregnancies. In our population, this approach for regulating access to invasive karyotyping can avoid a substantial number of unnecessary procedures, comparing favourably with current practice even in spontaneous pregnancies.