Prenatal testing for Down syndrome and neural tube defects has become routine, and testing for other genetic conditions is becoming commonplace. Counseling about these tests involves a discussion of risk information, so pregnant women and their partners can use the information effectively when they make choices about testing. Discussing risk can be challenging, as many individuals, particularly those of lower literacy, have a poor understanding of the numerical concept of risk. Furthermore, whether risk is comprehended accurately or not, it is interpreted by patients in light of their existing knowledge and past experiences. Strategies available to optimize understanding of risk include communication of risk figures as frequencies rather than as probabilities or percentages and explicit discussion of a woman's preconceptions about her risk and about the condition being tested for.