A validation study of early warning system in high-risk pregnant women.

High-risk obstetric patients have chances of deterioration which can be detected by any early warning score. This study was aimed to assess the suitability of the Obstetrics National Early Warning System (ONEWS) for the pregnant women. This prospective study was conducted on 500 high-risk pregnant women attending a tertiary care teaching hospital. The ONEWS charts were plotted for each of them. The primary outcome measure was composite adverse maternal outcome (CAMO) in the form of one or more among mortality, severe maternal morbidity and intensive care unit admissions. Of the 500 women who participated, 200 (40%) had a score ≥3 (triggered an intervention). The CAMO among the triggered group [59.5% (n=119)] was significantly higher compared to that in the non-triggered group [13.3% (n=40) (P=0.001)]. The area under the receiver operating characteristic curve was 0.800 (95% confidence interval 0.752-0.847). The sensitivity of the ONEWS in predicting CAMO was 74.8 per cent, specificity 76.2 per cent, positive predictive value 59.5 per cent and negative predictive value 86.7 per cent at a cut-off score of 3. ONEWS appears to be a useful tool for predicting adverse maternal outcomes in high-risk pregnant women.