Psychological measures have little sensitivity in the prediction of postnatal depression. We report the development of a questionnaire of beliefs about pregnancy and motherhood. Information from a literature review, staff working with women with postnatal depression and interviews with recently ill patients was used to develop a questionnaire called the PRBQ. The PRBQ was piloted on 42 pregnant women and achieved a Cronbach alpha of 0.85. Scores significantly correlated with scores on the Dysfunctional Attitude Scale (DAS), Beck Depression Inventory (BDI) and the Cognitive Adaptation to Stressful Events questionnaire (CASE), measuring adaptation to pregnancy. DAS and CASE scores did not correlate. The PRBQ and the CASE differentiated between those with (n = 5) and those without moderate depression. The PRBQ has been validated against established psychological measures. It may be a helpful tool contributing to the identification of women specifically at risk of postnatal depression. Further basic research is required.