The use of assisted reproductive treatment to conceive a child provides the opportunity for the state and/or medical practitioners to play a role in deciding who should or should not become a parent. This article explores the primary criteria used to "screen" people wishing to use assisted reproductive treatment and to exclude them from treatment in some circumstances. It argues that idiosyncratic judgment or general legal presumptions against treatment are not satisfactory, as they are unlikely to predict whether the best interests of a child born as a result of assisted reproductive treatment will be compromised. Rather, such judgments may serve to be discriminatory, and are often misinformed. The author suggests that the law and society should rather serve to support children and parents in need, and to protect existing children from actual suffering or risks of harm.