[Birth cohorts and their current status and prospects in China].

In the context of delayed marriage and parenthood, decreased willingness in having children, and population aging in China, maternal and child health has become an important and urgent issue. Being essential platforms for research in maternal and child health, the importance of birth cohorts has been widely recognized. In the past 20 years, tens of birth cohorts have been established in major cities and regions of China, with cohorts ranging from thousands to hundreds of thousands. These cohorts, particularly those large ones launched in recent years, have collected a wide spectrum of data and biological samples from mothers and children. Although they have made considerable preliminary achievements, there remain difficulties and challenges. The significant challenges include small and medium-sized cohorts' lacking of clear research themes; insufficient recognition of and emphasis on behavioral and social determinants of health while emphasizing biological determinants of health; variations in types of variables and quality of data collected, which make it difficult for cohorts to be merged and shared; lack of and difficulties in long-term follow-up; significant uncertainties in resources for long-term sustention of the cohorts, and so on. So, we argue that birth cohorts should focus on essential and urgent issues in maternal and child health in the country and seek recognition and support from the government and the entire society. Last but not least, the overall success of birth cohorts in the country requires scientists to be not only academically capable, but also realistic, persistent, altruistic, and collaborative.