Background: There is evidence that breastfeeding may provide protection against cardiovascular risk factors in mothers with a history of gestational diabetes mellitus and their children who were exposed in utero. Research Aim: To perform a systematic review and meta-analysis of observational studies to ascertain the effects of breastfeeding on cardiovascular risk factors in women with previous gestational diabetes mellitus and their children exposed in utero. Methods: Studies assessing conventional cardiovascular risk factors in women with previous gestational diabetes mellitus and children exposed in utero stratified by breastfeeding/no breastfeeding or breastfed/not breastfed were included. Gestational diabetes mellitus was defined based on the International Association of Diabetes in Pregnancy Study Group definition or previous accepted definitions. Breastfeeding was defined as reported in each study. Results: The literature search yielded 260 titles, of which 17 studies were selected to be in the review. Women with previous gestational diabetes mellitus who did not breastfeed had higher blood glucose ( SMD: 0.32, 95% CI [0.12, 0.53]) and a greater risk of developing Type 2 diabetes mellitus ( RR: 2.08 95% CI [1.44, 3.00]) compared to women with no history. There were not enough studies to conduct a meta-analysis on the effects of breastfeeding on risk factors for cardiovascular disease among children exposed to gestational diabetes mellitus in utero. Conclusion: Breastfeeding appears to be protective against cardiovascular risk factors among women who experience gestational diabetes mellitus.