Abstract: Objective To detect concentrations of heavy metals in umbilical cord blood of newborns and to explore its relationship with low birth weight among newborns in Shaoguan city of Guangdong province.Methods We used convenient sampling to select 1 036 pregnant women who giving birth to their children in two hospitals of Shaoguan city.The participants were asked to take a questionnaire survey and umbilical cord blood samples of the newborns were collected by well-trained doctors.Inductively coupled plasma mass spectrometry(ICP-MS) was used to measure the concentrations of heavy metals in the umbilical cord blood samples.Results The excessive rate of arsenic(As)was 72.49%,which was the highest among the heavy metals detected,and the excessive rate of stibium(Sb),selenium(Se),manganese(Mn),and barium(Ba)were 48.07%,34.07%,27.12%,and 14.48%,respectively.While,there were 93.24%,46.81%,94.11%,and 64.19% of the umbilical cord blood samples had lower concentrations of calcium(Ca),ferrum(Fe),cuprum(Cu),and zinc(Zn)than the reference range,respectively.All the heavy metals were associated with low birth weight except for Mn.The newborns with low birth weight had higher concentrations of As,Cd,Sb,and Ba,but lower concentrations of some essential metals such as magnesium(Mg),Ca,and Fe compared to those of the newborns with normal birth weight.Conclusion The results indicated that pollution of some heavy metals was serious but a number of newborns had lower concentrations of some essential metals than the reference range in the area surveyed,and the incidence of low birth weight among the newborns was associated with the concentrations of these metals in umbilical cord blood.