The importance of gut microbes to human health has gradually attracted attention. With the use of animal models, it has been revealed that maternal microbes during pregnancy could influence their children's health outcomes through shaping their microbial composition and regulating the development of their metabolic and immune system. However, the physiological mechanism of the human body is more complex and is affected by the interaction of multiple factors. The research results obtained from animal models are often inconsistent with human studies. At present, the influence of maternal intestinal microbes during pregnancy on the microbial colonization in their offspring and on a series of children's health outcomes is still unclear. Establishing a sub-cohort to detect the microbiome of the women across pregnancy and of their offspring, and further to integrate with variety of environmental and behavioral exposures can better provide reliable support for the research on the mechanism of children's health and diseases. This paper briefly introduces the research objectives, content, progress, strength and limitations of the sub-cohort study.

Birth cohort is an effective method to explore the relationship between various prepregnant and pregnant exposures and the health of fetuses, infants and young children. It is a long construction period to build a birth cohort and the quality of research may be affected by many factors. This paper reviews the quality assurance and quality control measures in the process of China National Birth Cohort (CNBC), and summarizes the construction experience. We aim to provide experience for related cohort studies, which could improve the quality of cohort studies through removing the impact of related factors. CNBC adopted a series of measures to ensure the quality of research in the top-level design of quality assurance, including screening research center, developing member management system, formulating standard operating procedures and training staff by it. In terms of quality control, it includes real-time, timely and timing quality control for the process of data generation, full-cycle quality control for biological sample collection, processing, storage and comprehensive three-dimensional quality control for staff training, supervision and quantitative assessment.

引起手足口病的肠道病毒有很多种，多种血清型病毒的共同流行和传播，增加了共同感染和基因重组的风险。肠道病毒A71型（EV-A71）是导致手足口病重症和死亡的主要病原，对儿童健康构成严重威胁。接种EV-A71疫苗对减少手足口病对儿童健康的危害具有重要意义。

The endothelial NO synthase (eNOS) enzyme is expressed during the early stages of cardiogenesis and plays an important role in normal heart development. Genetic variations of eNOS G894T have been shown to influence individual susceptibility to some phenotypes of congenital heart disease (CHD) in different populations. We conducted a case-control study comprised of 945 CHD patients and 972 non-CHD individuals in a Chinese population. Two functional single nucleotide polymorphisms (SNPs) (T-786C: rs2070744 and G894T: rs1799983) and one tagging SNP (rs7830) were evaluated in our study, and we assessed their association with the risk of CHD. Compared with the rs7830 CC/AC genotypes, the eNOS rs7830 AA genotype showed a significantly increased risk of CHD (adjusted odds radio (OR) = 1.45, 95% confidence interval (CI = 1.13-1.85). A stratified analysis was performed and showed that the association between the rs7830 AA genotype and CHD risk was stronger in patients with perimembranous ventricular septal defects (adjusted OR = 1.62, 95%CI = 1.20-2.20). Our results suggest that the eNOS rs7830 polymorphism may contribute to the susceptibility of sporadic CHD in a Chinese population.