Objectives: Investigate the potential factors associated with high weight gain and high BMI status in the first three months of life. Methods: Totally, 930 healthy neonates (489 boys and 441 girls) were involved in this community-based, prospective study in China. Data on body weight and length were collected at birth, and the 1st and 3rd months. A self-administered questionnaire was used to collect data regarding social demography, gestational status, delivery, and the feeding patterns of children. Results: Prevalences of high BMI status (BMI = 85th p, re WHO BMI standards) increased over time in both sexes, reaching 24.5% and 12.0% for boys and girls, respectively. General linear mixed models indicate high BMI status at 3 months is significantly and inversely associated with breastfeeding, as a proportion of feeding occasions [OR 0.74 (95%CI: 0.56-0.98)] and positively with lower birth weight [OR 2.07 (95%CI: 1.23-3.49)]. High weight gain (=85th p, re WHO velocity standards) in the first 3 months is also significantly associated with breastfeeding [OR 0.76 (95%CI: 0.59-0.96)] and sex, with boys at a higher risk than girls [OR 1.44 (95%CI: 1.07-1.97)]. Living in an extended family is associated with both high weight gain and high BMI status, but with marginal statistical significance. Conclusion: Analyses indicate an increasing trend of high BMI status in early infancy. Breastfeeding provides a protective effect for both high weight gain and high BMI status. The results concerning birth weight suggests a target for intervention.