Objective To investigate the changes of health status of non-registered children aged 0-6 years in Shanghai in 2009 and 2017.

Methods A stratified randomized cluster sampling method was used to investigate the health status of household registered and non-registered children aged 0-6 years old in the same community health service centers.Inquiry card and questionnaire were used for collection and retrospective investigation of data on their health card establishment, physical growth and diets.

Results The rate of health card establishment among non-registered children was lower than that among registered ones.The weight and height proportion of less than P₃ was higher in non-registered children than in registered ones in 2009 while there was no difference found between the two groups in 2017.The weight proportion of more than P₉₇ and the incidence of obesity were lower in non-registered children than in registered ones in 2009 while there was no difference found in 2017.As compared with 2009, the height proportion of less than P₃ and the incidence of obesity in non-registered and registered children were higher in 2017 while the weight proportion of more than P₉₇ was lower.The incidence of anemia in registered children was lower in 2017 than in 2009.The proportion of diet problems was higher in non-registered children than in registered ones in 2017 and 2009.

Conclusion The physical growth and health problems in non-registered children have remarkably changed during the eight years, and their partial and picky food problems still exist.More attention should be paid to child health care education and guidance.