PubMedCovers 1966-present. Contains citations from a broad array of biomedical journals. Useful MeSH (medical subject headings) include questionnaires, psychological tests, health status rating scales, psychiatric status rating scales, and personality inventory.
--In PubMed, not all instruments fall under MeSH headings, so try a keyword search such as pregnancy AND questionnaire. Other keywords to consider include inventories, scale measure, measurements, survey, and psychometrics.