Objective  To investigate associations of family daytime care and formal daytime care (kindergarten/nursery care) on overweight/obesity among children aged 3 – 6 years in China and to provide evidences for developing strategies of intervention on childhood obesity.

  Methods  Information on 2 725 children aged 3 – 6 years from nine provinces and three municipalities were extracted from the datasets of eight waves of China Health and Nutrition Survey between 1991 and 2011. The children′s body mass index Z-score (BMIZ) was calculated to assess the status of overweight/obesity. The effects of different daytime care on overweight/obesity and influence pathways of the effects among the children were assessed with binary logistic regression.

  Results  Among all the children, the overweight/obesity rate was 20.99% and the rate (22.08%) was significantly higher among the children with family care than that (15.82%) among those with formal care (kindergarten/nursery care). The results of logistic regression analysis indicated that the children with formal care were less likely (odds ratio OR = 0.598, 90% confidence interval 90% CI: 0.465 – 0.770; P = 0.001) to have overweight/obesity but more likely (OR = 2.204, 90% CI: 1.715 – 2.833, P < 0.001) to participate in physical exercise compared to the children with family care; however, the children with formal care were more likely (OR = 2.204, 90% CI: 1.715 – 2.833, P < 0.001) to intake slightly high amount of fat than the recommended in comparison with the children with family care.

  Conclusion  Formal care can reduce the probability of overweight and obesity and physical activity plays an important role in prevention and control of overweight and obesity among 3 – 6 years old children.