Common sayings like "children are the future of our world" and "children are not small adults" reflect our deep understanding of the importance of the health and growth of children as a special group. Various adverse factors experienced in early life (including embryonic stage and infancy) would affect growth and development of fetuses and infants, even associate with adulthood diseases. Birth cohorts, especially those start from the first trimester, can provide the best longitudinal data for children's environmental health research. Non-retrospective data collection, particularly the collection of biological samples, can provide an objective evaluation of the relationships between environmental exposure at different stages and health indicators in later stages. The World Health Organization (WHO) proposed children's environmental health indicators (CEHI) in the 20th century to monitor environmental (change) trends, to determine the potential health risks, and to evaluate underlying correlations between environment and health outcomes. We should take advantage of the experience of birth cohorts conducted in other countries with an international perspective, ensure the quality of data and the normalization of observation indicators, and furthermore make each cohort with its own characteristics.