This systematic review aims to assess the effect of mindfulness-based interventions carried out during pregnancy exploring mindfulness and mental health outcomes. A systematic review was conducted to appraise the current literature on the subject area. Inclusion and exclusion criteria were agreed and after reviewing titles, abstracts and full papers, 14 articles met the inclusion criteria and were included in the review. The quality of included articles was checked using the Quality Assessment Tool for Quantitative Studies. Pooled results of the randomised controlled trials (RCTs) reporting outcomes on anxiety, depression and perceived stress indicated no differences between the mindfulness intervention group and the control group. Pooled results of the non-RCTs reporting anxiety, depression and perceived stress showed a significant benefit for the mindfulness group. Mindfulness as an outcome was assessed in four RCTs for which the pooled results show a significant difference in favour of the mindfulness intervention when compared to a control group. The pooled results of the four non-RCTs also indicate a significant difference following mindfulness intervention. Results suggest that mindfulness-based interventions can be beneficial for outcomes such as anxiety, depression, perceived stress and levels of mindfulness during the perinatal period. Further research would be useful to explore if such benefits are sustained during the post-natal period.