Abstract leptin and insulin have been implicated in fetal growth regulation and investigated repeatedly with controversial outcomes. A systematic review and meta-analysis were conducted according to MOOSE guidelines to establish if consistency exists in the reported literature so that the role of maternal and fetal insulin and leptin in fetal growth could be assessed. A robust recognised systematic methodology was used in the literature search and data extraction and analysis to avoid bias. SPSS version 16 and RevMan 4.2 were used for statistical analysis and the results presented as a Weighted Mean Difference (WMD) and 95% CI. Nineteen studies were included. Large for gestational age babies (LGA) had significantly higher cord serum insulin and leptin levels than was adequate for gestational age (AGA) ones[3.16 µIU/ml (0.85, 5.48) and -4.33 ng/ml (-5.30, -3.36) respectively]. Small for gestational age babies (SGA) had similar insulin levels but significantly lower cord leptin[21 µIU/ml (-5.69, 1.27)] than AGA babies [-3.07ng/ml (-4.57, -1.58)]. Maternal serum levels of leptin were similar between mothers of LGA, SGA and AGA babies. Conclusion: although both fetal insulin and leptin reflect the degree of fetal adiposity, leptin may have growth promoting properties
