Objective: To evaluate the effect of a dietary and exercise intervention on cognition and behaviors among primary school students, and to further explore the mediating role of family support, in order to provide scientific evidence for future effective intervention strategies. Methods: A dietary and exercise intervention program for childhood obesity prevention was carried out in 24 primary schools in Beijing, Changzhi and Urumqi from 2018 to 2019, and 1 392 children in grade four as well as their parents were included. Family support and children s cognition and behaviors were collected through questionnaire. To carry out diet and exercise behavior intervention on the three levels of school, family and individual in the intervention group,and children s dietary and exercise knowledge, eating habits, physical activities, as well as sedentary and screen behaviors were evaluated. The linear mixed model was used to analyze the effect of intervention on children s cognition and behaviors, and the mediation model was used to explore the role of family support. Results: The proportion of children with higher score of dietary and exercise knowledge ( OR= 2.34 , 95%CI =1.71-3.21), eating habits ( OR=2.58, 95%CI =1.75-3.82), and sedentary and screen behaviors ( OR=1.91, 95%CI =1.35-2.68) increased in the intervention group after one year intervention ( P <0.01), compared with the control group, respectively. The intervention also increased the proportion of children s family support in the intervention group compared with the control group ( OR=3.45, 95%CI =2.19-5.45), and the support from children s fathers ( OR=2.70, 95%CI =1.68-4.35), mothers ( OR=3.71, 95%CI =2.28-6.04), paternal grandmothers ( OR=1.65, 95%CI =1.00-2.70), and maternal grandmothers ( OR= 2.14, 95%CI =2.12-2.16) increased significantly ( P <0.05). The mediation analysis showed that family support played a mediating role in association between comprehensive intervention and children s eating habits as well as sedentary and screen behaviors. Conclusion The dietary and exercise intervention effectively promoted children s cognition and behaviors, and family support played an important mediating role.

Objective: To evaluate the immunity and influencing factors of diphtheria among preschool children in Shenzhen,to provide reference for effective monitoring of diphtheria IgG antibody level in preschool children. Methods: Serum samples were collected from 296 preschool children aged 4-6 who were recruited in Shenzhen. The diphtheria antibody titer in serum was determined by enzyme linked immunosorbent assay, and the effect of different immumuzation schedule including types of vaccine and vaccination timing, on the geometric mean concentration (GMC) of diphtheria IgG antibody and antibody positive rate were analyzed. Results: The GMC of diphtheria IgG antibody was 0.71 IU/mL, and the positive conversion rate was 33.1%. There were significant differences in antibody GMC and antibody positive conversion rate of diphtheria in different age groups( F/χ 2=11.77, 27.45, P < 0.01 ). The GMC and antibody positive conversion rate showed significant differences by diphtheria antibodies, vaccine types and end dose vaccination intervals( F=49.53, 12.95，11.61, P <0.01). There were statistically significant differences in the positive conversion rate of diphtheria antibodies in children with different types of diphtheria antibodies, vaccine types of diphtheria antibodies, and diphtheria antibodies at the time interval of final vaccination (Fisher exact probability method, P <0.01). Conclusion The overall positive conversion rate of diphtheria antibody in preschool children in Shenzhen is high. Timely completion of full diphtheria vaccination can improve the antibody level and plays a better role in protecting preschool children.

Objective:To quantify the associations between periconceptional maternal homocysteine (HCY) and offspring′s birth weight and risk of small for gestational age (SGA) infant.Methods:The 19 984 mother-child pairs in this prospective cohort study were recruited from the Shanghai preconception cohort; the infants were delivered from 1 st September 2016 to 11 th November 2022. A standardized questionnaire was used to collect the mothers′ demographic information, medical history, dietary supplement use, and maternal complications during pregnancy, and their serum samples were collected. Serum HCY, folate, and vitamin B 12 were measured using chemiluminescent microparticle immunoassay based on serum sample drawn at enrollment. Birth weight data were obtained from medical records. Multiple imputation methods were applied to handle missing data in key variables. Multivariable linear regression and Poisson regression models were used to analyze the relationship between maternal HCY concentration during the periconceptional period and the birth weight and SGA risk of the offspring. Results:A total of 9 452 pairs were enrolled preconceptionally and the remaining 10 532 pairs were enrolled in early pregnancy. The proportion of mothers whose pregnancy age was greater than 35 years was 9.2% (1 832/19 984), the proportion of primiparous women was 76.5% (15 283/19 984), the proportion of pre-pregnancy overweight and obesity was 14.0% (2 804/19 984), the proportion of using folic acid supplements before pregnancy was 21.4% (4 272/19 984), and the proportion of those who supplemented with folic acid during early pregnancy was 85.2% (8 976/10 532); gestational diabetes mellitus was in 6.2% (1 245/19 984), gestational hypertensive syndrome in 3.6% (711/19 984). The birth weight of the offspring was (3 297±468) g, and there were 1 962 SGA children (9.8%). The HCY concentration in the overall population in appropriate for gestational age during the periconceptional period was (7.9±3.2) μmol/L, with (8.3±3.7) μmol/L in the preconception subgroup and (7.3±2.4) μmol/L in the early pregnancy subgroup. After adjustment for the covariates of perinatal demographic information, adverse pregnancy outcomes, serum folate and vitamin B 12, increased maternal periconceptional HCY was significantly associated with lower offspring birth weight ( β=-2.30, 95% CI -4.43--0.16, P=0.035). Only the early pregnancy subgroup was significantly associated with lower offspring birth weight ( β=-7.39, 95% CI-11.50--3.21, P<0.001). No association was found between peripregnancy HCY and offspring SGA risk. However, elevated HCY in early pregnancy was associated with an increased risk of SGA in the offspring ( RR=1.05, 95% CI 1.01-1.08, P=0.002). Periconceptional vitamin B 12 was a mediator of the association between HCY and offspring birth weight, accounting for 16.5%, 41.2% and 5.4% of its total effect in the overall periconceptional population, the pre-pregnancy subgroup and the early pregnancy subgroup, respectively. Conclusions:Maternal periconceptional HCY level is associated with lower birth weight in offspring, but not with the risk of SGA. Elevated maternal HCY in early pregnancy subgroup may be associated with increased risk of SGA in offspring.