This is a case report of a 35-year-old women who had spontaneous pneumomediastinum (SPM) during the second stage of labour. Although this condition during labor is very rare, it is described in the literature as Hamman's syndrome. The symptoms are dyspnoea, chest pain and subcutaneous emphysema which leads to much more severe differential diagnoses that should be eliminated quickly. There has not yet been found any dispositions to the condition. Duration of the second stage of labour is a theoretic factor of relevance, which naturally puts nulliparas at a higher risk.