Postpartum stress incidence rate is quite high (26% - 85%). Several studies reveal that more than 50% of women experience stress and depression after giving birth and almost 80% of new mothers experience terrible sadness feelings after giving birth, often called postpartum stress. This study aims to determine the effect of postpartum coping skill classes (PCSC) on stress level, cortisol level, maternal self-efficacy (MSE), and baby's growth and development. This study employed an experimental design method with a randomized study pre-test post-test control group design. The study was conducted on 18 postpartum women who were given PCSC treatment which was integrated into postpartum classes and 17 women were given postpartum classes (PC) only. The study was conducted in 4 weeks. The data were analyzed statistically using a t-test method. Ethical clearance for the study was obtained. The results disclose that PCSC significantly decrease the PSS score (-2.66 ± 4.74, p = 0,029). Similarly, the cortisol level drops significantly (-38.53 ± 74.60, p = 0.031). In other respect, the MSE score between groups have significant mean difference (p = 0.013), but the weight gain and development of the baby between the two groups have no significant mean difference (p >0.05). The provision of coping skill classes through maternal classes for postpartum women was effective in decreasing stress levels, cortisol levels, and increasing MSE scores although it did not affect the baby's growth and development.