- AIMS: This study sought to develop and begin validation of an indirect screener for identification of drug use during pregnancy, without reliance on direct disclosure. DESIGN: Women were recruited from their hospital rooms after giving birth. Participation involved (i) completing a computerized assessment battery containing three types of items: direct (asking directly about drug use), semi-indirect (asking only about drug use prior to pregnancy) and indirect (with no mention of drug use), and (ii) providing urine and hair samples. An optimal subset of indirect items was developed and cross-validated based on ability to predict urine/hair test results. SETTING: Obstetric unit of a university-affiliated hospital in Detroit. PARTICIPANTS: Four hundred low-income, African American, post-partum women (300 in the developmental sample and 100 in the cross-validation sample); all available women were recruited without consideration of substance abuse risk or other characteristics. MEASUREMENTS: Women first completed the series of direct and indirect items using a Tablet PC; they were then asked for separate consent to obtain urine and hair samples that were tested for evidence of illicit drug use. FINDINGS: In the cross-validation sample, the brief screener consisting of six indirect items predicted toxicology results more accurately than direct questions about drug use (area under the ROC curve = 0.74, P < 0.001). Traditional direct screening questions were highly specific, but identified only a small minority of women who used drugs during the last trimester of pregnancy. CONCLUSIONS: Indirect screening may increase the accuracy of mothers' self-reports of prenatal drug use.