Validation of the 30-item General Health Questionnaire in early pregnancy.

One-hundred-and-seventy-nine women attending their first antenatal clinic at two general practices in South London were asked to complete the 30-item General Health Questionnaire (GHQ-30) as part of a larger prospective longitudinal study into childbirth-related affective disorders. The women were later interviewed at home and a standardized psychiatric interview administered. Relative operating characteristic (ROC) curves were used to determine the optimum cut-off point on the GHQ-30. Thirty-five per cent of the women were high scores on the GHQ-30 (greater than or equal to 6) and 29% were found to be 'cases' at interview (CIS Overall Severity Rating greater than or equal to 2).