To determine the validity of the Asthma Control Test (ACT) questionnaire for assessing pregnant asthmatic women.

The study involved 40 pregnant asthmatic women over a total of 113 medical visits. On each occasion the participants had a pulmonary function test and a clinical evaluation to assess the level of asthma control. In addition, the ACT was carried out with the obstetrician being blinded to its results.

The most accurate cut-off point was 16, with a sensitivity of 95.4%, specificity of 68.8%, a negative predictive value of 91.7% and a positive predictive value of 80.5%. The positive and negative likelihood ratios were 3.052 and 0.067 respectively. The questionnaire was found to be highly effective for discriminating between controlled and uncontrolled asthma, with an area under the receiver operating characteristic (ROC) curve of 0.846 (95%CI: 0.748–0.92). Reliability assessed in patients with the same clinical classification resulted in an intra-class correlation coefficient of 0.86 (95%CI: 0.75–0.93). Improved clinical conditions corresponded to a significant increase in the ACT score (p < 0.005), indicating good responsiveness to changes in clinical status.

The ACT proved to be reliable and could discriminate between levels of asthma control in pregnant women confirming its value as a useful tool for the management of asthma during pregnancy.