Relationship Between Serum Lead Level During Pregnancy And Motor Development Of 18-month-old Children And The Protective Effect Of Selenium On Lead Induced Motor Developmental Delays

ObjectivesTo evaluate the level of serum lead in early,middle and umbilical blood,to analyze the relationship between lead levels during pregnancy and and 18 months old children's motor development and their gender differences,and to reveal the protective effect of high selenium level in early pregnancy on lead-induced motor development delays in early childhood.MethodsProspective cohort study design was implemented in our study and pregnant women were recruited in the Ma'anshan Birth Cohort study conducted in the Maternal and Child Health?MCH?Center in Ma'anshan city,Anhui Province,China from May 2013to September 2014.Baseline demographic data of pregnant women and infants,and information on pregnancy complications were collected through through questionnaires and access to newborn birth records.Meanwhile,blood samples were collected from the first,second trimester of pregnancy and parturition,heavy metals in serum were detected by inductively coupled plasma mass spectrometer?ICP-MS?.The Ages and Stages Questionnaires of third edition?ASQ-3?was performed to evaluate motor development of toddlers in 18 months old.A total of 2 653 maternal-singleton pairs wereobtainedinthisstudy,including2410,2534,and2239serum samples were obtained from pregnant women in the first,second trimester and the umbilical cord blood,respectively.Considering the distribution characteristics of variables,Mann-Whitney U test and Kruskal-Wallis H test were used to compare the differences of serum lead levels among groups.Restricted cubic spline models were used to consider potential non-linear associations between lg-transformed Pb and the risk of The relationship between serum lead in the first trimester and motor development delays was fitted by using the restricted cubic spline models to describe the tendency of the occurrence of the risk of motor development delays,and the hazard threshold was found to classify the level of serum lead.Logistic regression models were used to examine serum Pb levels and the risk of Logistic regression model was used to evaluate the relationship between maternal serum and umbilical cord serum lead level and motor development delays in toddlers of 18 months old and the relationship between serum selenium in early pregnancy and motor development delays induced by lead.ResultsThe levels of serum lead in pregnancy decreased with the progress of pregnancy:the levels of serum lead in first,second trimester and the umbilical cord blood,were 910ng/L,830 ng/L,700 ng/L,respectively.And the results of our study show that in 2 653toddlers the prevalence of developmental delay was 3.3%in gross motor domain,3.9%in fine motor domain.The univariate logistic regression analysis between lead level during pregnancy?continuous variable?and children's motor development showed that the risk of early pregnancy lead level and 18 months old children's motor development delays was 2.19?95%CI:1.18,4.05;P=0.013?,after adjusting for the potential confounding factors,the risk of early pregnancy lead level and 18 month old children with developmental retardation was 2.47?95%CI:1.23,4.95%;P=0.011?.Under the condition of sex stratification,the logistic regression analysis between the early pregnancy lead level and the children's motor development was as follows:before and after adjusting the confounding factors,the lower levels of lead in the two groups were taken as the reference group.The risk of gross motor development delaysin boys exposed to high level lead was 2.23?95%CI:1.02,2.87;P=0.045?and 2.49?95%CI:1.01,6.16;P=0.048?.On the basis of this,the relationship between selenium in early pregnancy and motor development delays induced by lead was further explored.The serum selenium concentration P₇₅5 was divided into two groups,<P₇₅5 and?P₇₅.Univariate and multivariate logistic regression analysis between selenium concentration in first trimester and children's motor development delays at 18 months of age showed that,there was no significant difference between the level of selenium in early pregnancy and the risk of motor development delays?p>0.05?.Finally,the selenium level and sex in early pregnancy were stratified,and logistic regression analysis was used.Before and after adjusting the confounding factors,the results showed that,in the lower selenium level group,pregnant women with high levels of lead had 4.41?95%CI:1.32,14.75;P=0.016?and 4.20?95%CI:1.22,14.50;P=0.023?risks of motor development delays in boys of 18 months old.However,there was no significant difference in the risk of high levels of lead and motor development in pregnant women with higher selenium levels.ConclusionThe higher serum lead level in early pregnancy increased the risk of gross motor delays in 18-month-old children,and there was a gender difference,which showed that high levels of serum lead increase the risk of motor development delays in boys.The high level of selenium in early pregnancy has protective effect on the development delays of children's motor development induced by lead.