The 2003–2005 Confidential Enquiry into Maternal and Child Health report recommended the introduction of the modified early obstetric warning system (MEOWS) in all obstetric inpatients to track maternal physiological parameters, and to aid early recognition and treatment of the acutely unwell parturient. We prospectively reviewed 676 consecutive obstetric admissions, looking at their completed MEOWS charts for triggers and their notes for evidence of morbidity. Two hundred patients (30%) triggered and 86 patients (13%) had morbidity according to our criteria, including haemorrhage (43%), hypertensive disease of pregnancy (31%) and suspected infection (20%). The MEOWS was 89% sensitive (95% CI 81–95%), 79% specific (95% CI 76–82%), with a positive predictive value 39% (95% CI 32–46%) and a negative predictive value of 98% (95% CI 96–99%). There were no admissions to the intensive care unit, cardio respiratory arrests or deaths during the study period. This study suggests that MEOWS is a useful bedside tool for predicting morbidity. Adjustment of the trigger parameters may improve positive predictive value.