Objective: To examine the independent and combined effects of pre-pregnancy BMI and gestational diabetes (GDM) on early adiposity rebound (AR) timing in children. Methods: Based on the "Ma'anshan Birth Cohort Study", 2 896 eligible maternal and infant pairs were recruited. In the cohort, we collected pre-pregnancy height, weight, 24 to 28 weeks GDM diagnosis, follow-up at 42 days, three months, six months, nine months of age, and every six months after one year of age, and continuously followed up to 6 years old, and obtained the child's length/height, weight, and other data. The intensity of the association between pre-pregnancy BMI, GDM, and early AR timing was analyzed by the multivariate logistic regression model. Multiplication and additive models were used to analyze how pre-pregnancy BMI and GDM influenced early AR timing in children. Results: The prevalence of underweight, average weight, overweight, and obesity before pregnancy were 23.2% (672), 66.4% (1 923), 8.7% (251), and 1.7% (50). The prevalence of GDM was 12.4%. We found that 39.3% of children had AR, and the average age at AR was (4.38±1.08). The results of multifactorial logistic regression analysis showed that pre-pregnancy overweight (OR=1.67,95%CI:1.27-2.19), pre-pregnancy obesity (OR=3.05,95%CI:1.66-5.56), and maternal GDM (OR=1.40,95%CI:1.11-1.76) were risk factors for early AR timing in children. In contrast, pre-pregnancy underweight (OR=0.60,95%CI:0.49-0.73) was a protective factor for early AR timing in children. Compared with the different effects of pre-pregnancy overweight/obesity and maternal GDM alone, the combined effect caused a higher risk of early AR timing in children, with OR values (95%CI) were 2.03 (1.20-3.44), 3.43 (1.06-11.12), respectively. The multiplication and additive models showed no interaction between pre-pregnancy BMI and GDM-influenced early AR timing in children. Conclusion: Higher pre-pregnancy BMI and maternal GDM are the independent risk factors for the early AR timing in children, and the co-occurrence of the two is higher risks, but there was no statistical interaction.