Objective: To explore the correlation among the pre-pregnant body mass index (BMI), gestational weight gain (GWG) and umbilical cord blood C peptide, and to investigate the influence of maternal weight management on the incidence of baby long-term metabolic syndrome. Methods: During May to Aug.2015, 485 pregnant women in Zhejiang Taizhou first people's hospital and Taizhou Huangyan maternal &child care service centre were selected in random and divided into four groups according to pre-pregnant BMI: low body mass, normal body mass, over body mass and obese group, and also divided into two groups for getting gestational diabetes mellitus (GDM) or not. According to the gestational weight gain (GWG), all the cases were divided into two groups: above the Institute Of Medicine (IMO) 2009 recommendations or not. According to the outcome, the GDM group which had received weight control treatment, was divided into successful treat group or not. At last, we tested the umbilical cord blood C peptide and birth weight of each newborn and compared the difference in all subgroups. The correlation between the umbilical cord blood C peptide and birth weight were analysed. Results: (1) In the pre-pregnant BMI groups, there were significant differences of incidence of GDM (P<0.05). But, there were no significant differences of incidence of GWG in four groups (P>0.05). (2) Newborn birth weight and the umbilical cord blood C peptide were positively correlated (r=0.673, P<0.05). (3) Umbilical cord blood C peptide showed the correlation in all subgroups for different pre-pregnant BMI, GDM or not, overweight or not (P<0.05), but only the GDM or not group had relation to newborn birth weight in all subgroups. (4) All groups showed correlations with neonatal umbilical cord blood C peptide, the GDM mostly (β=0.58), pre-pregnant BMI secondly (β: 0.36, 0.38) , and GWG weakly (β=0.17). (5) By stratification analysis, in GDM group, low body mass was negatively correlated with umbilical cord blood C peptide (P<0.05, β=-1.41); in non-GDM group, over body mass group and obsess group were positively correlated with umbilical cord blood C peptide (P<0.05, β=0.37, 0.46). Conclusion: There was direct correlation between the pre-pregnant body mass index, the gestational weight gain and umbilical cord blood C peptide. Suitable maternal weight control especially pre-pregnant body mass index control will lower the baby long-term metabolic syndrome incidence.