One of the serious stress factors is the birth of a premature infant, which causes significant stress in mothers and affects their quality of life. Reducing the mother's stress will cause an improvement in the quality of care of the infant and, as a result, better outcomes. The current study was done to investigate the effect of mindfulness exercises on the stress of mothers with premature infants. This research was done with a pre-test-post-test design along with a control group and non-random allocation of samples, which was conducted on 72 mothers with premature babies. In addition to routine care, the mothers of the intervention group received eight sessions of mindfulness training in the form of face-to-face group and virtual sessions. Mothers in the control group did not receive the new intervention. To collect data, two demographic information questionnaires and a parental stress scale were used. Questionnaires were completed before and one month after the intervention, which coincided with the last session of mindfulness exercises. SPSS version 23 software and descriptive and inferential statistical tests were utilized to analyze the data. According to the obtained results, before the implementation of the intervention, the mean and SD (standard deviation) of the stress scores of the mothers in the control and test groups were not significantly different (P>0.05). After the intervention, the mean and SD of mothers' stress scores in the control and test groups were significantly different (P<0.05). The results of univariate covariance analysis showed that mindfulness exercises significantly reduced the stress of mothers in the intervention group compared to the control group with a large effect size.
