Lifestyle changes over the last two decades have led to an increase in pregnancy-related complications due to metabolic factors. It is therefore important to examine interventions that can ameliorate this situation. The objective of this chapter is to examine the effects of probiotics on metabolic parameters in normal pregnant women and in those with gestational diabetes mellitus (GDM), through a metaanalysis of pertinent randomized control trials. It is found that probiotics may be safely used to positively influence the glycemic metabolic factors (glucose, insulin, HOMA-IR, weight), triglyceride-related lipids (VLDL, triglycerides), and oxidative stress factors in pregnant women, and minimize their risks for GDM and other metabolic abnormalities.