Objective To investigate the trend of early neural development in premature infants. Methods At the age of 12 months and 24 months, Bayley Scales of Infant Development were used to assess the mental development index (MDI) and the psychomotor development index (PDI) in preterm (corrected age) and full-term infants. Results At 12 months, there was no significant difference in corrected age PDI scores among different gestational age groups (<32 , 32–33+6 and 34–36+6 weeks) (P=0.820). The actual age MDI and PDI scores of full-term infants and premature infants in 34~36+6 weeks group were significantly higher than those of premature infants in <32 and 32-33+6 weeks groups, and the PDI score of full-term infants was significantly higher than that of premature infants in 34-36+6 weeks group (P<0.05). There was no significant difference in actual age PDI scores among different birth weight groups (P=0.166). The actual age MDI and PDI of full-term infants and premature infants in birth weight≥2500 g group were significantly higher than those of premature infants in <1500 g, 1500~1999 g and 2000~2499 g groups (P<0.05). At 24 months, the actual age MDI scores of full-term infants were significantly higher than those of premature infants in different gestational age and birth weight groups (P<0.05). The actual age MDI curve of premature infants in birth weight <1500g group showed a downward trend, while the actual age PDI curve showed a significant upward trend. Conclusion The neurodevelopment of preterm infants at the corrected age of 12 and 24 months reaches the level of full-term infants.

Objective: To establish the norm of the Physical Activity afterschool Questionnaire for Preschooler(P-PAQ) in urban areas of China, so as to provide a basis for graded guidance from the family perspective and to improve children s physical activity levels. Methods: From October 2020 to January 2021, 6 267 children aged 3-6 years old were recruited from 40 kindergartens in eight cities across six major administrative regions by stratified cluster sampling, and the P-PAQ initially developed by the researchers of this study were completed by the primary caregivers. The questionnaire was administered to collect data relating to the amount of physical activity undertaken by the preschoolers, and the norm was determined by quartiles. Data relating to parental concepts of sports and parental behavior were assessed by calculating mean scores in order to establish the norm. Results: Among preschoolers in urban areas, the M(P 25 ，P 75 ) of total physical activity time (min/day), moderate-to-vigorous physical activity time (min/day), outdoor time (min/day) and screen time (min/day) on school days outside kindergarten and on weekends were 84 (54,120), 22 (8,40), 12 (0,24) and 18 (6,30), and 170 (115,240), 60 (30,95), 90 (35,120) and 30 (20,60), respectively. When the score of parents sports concept and behavior (total score of 40) were≥34, 29-<34, 24-<29, <24, it was defined as four levels about above medium, medium, lower medium and lower, respectively. And for two dimensions，when the score of parental sports concept were ≥19, 17-<19, 15-<17, <15，and the score of parental behaviors were ≥16, 12-<16, 8-<12, <8, it was defined as four levels about upper medium, medium, lower medium and lower, respectively. Conclusion The norm of extracurricular activities among preschool children in Chinese cities has good representativeness and appropriate threshold values, which could provide a valuable reference for early assessment, as well as guidance in relation to out-of-school physical activity behaviors among children aged 3-6 years old.