Both patients and physicians can be overwhelmed by the many options for Down syndrome screening available today. Fortunately, there are several current protocols for sensitive and specific first-, second-, and combined first- and second-trimester screening. Modeling indicates that the most sensitive and specific option is contingent screening, in which all women undergo first-trimester screening and only 25% proceed to second-trimester screening. Contingent screening detects 85% of all Down syndrome cases, with only a 1.3% screen-positive rate, thus limiting the number of invasive diagnostic procedures recommended and reducing the number of procedure -related fetal losses