Objectives: To systematically review the literature on the use of probiotics in pregnancy and their impact on maternal outcomes. Methods: Online databases were searched in April 2012 using the following terms to identify eligible studies: "probiotics", "pregnancy", "maternal outcomes" and "metabolism". Primary outcomes of selected studies were maternal fasting glucose during pregnancy and rates of gestational diabetes mellitus (GDM). Secondary outcomes were rates of pre-eclampsia, maternal inflammatory markers and lipid profiles and gestational weight gain. Studies whose primary outcomes were bacterial vaginosis, pre-term delivery and infant atopy were excluded. Only English-language articles were included. The limited number of eligible studies and varying outcomes precluded formal meta-analysis of these data. Results: Initially, 189 articles were identified and screened. Seven articles met inclusion criteria and are included in the present review. Results demonstrated that probiotic use in pregnancy could significantly reduce maternal fasting glucose, incidence of GDM and pre-eclampsia rates and levels of C-reactive protein. Conclusions: Probiotics hold potential as a safe therapeutic tool for the prevention of pregnancy complications and adverse outcomes related to maternal metabolism. Further randomised controlled trials are urgently required, particularly among those at high risk of metabolic disorders, such as overweight and obese pregnant women.