AIMS: To investigate the association of gestational weight gain (GWG) trajectory with early children growth, and explore whether this association varies by gestational diabetes mellitus (GDM) status. METHODS: Maternal weight and offspring anthropometric outcomes before 36 months were extracted from Electronic Medical Record of Zhoushan, China. GWG trajectory was modeled using latent-class trajectory analysis. Multiple generalized estimating equations models were applied to analyze associations of GWG trajectory categories with early children growth. RESULTS: Three GWG trajectory classes were identified in all participants (n = 13 424), the non-GDM (n = 10 984) and GDM (n = 2440) groups, respectively. In all participants, the Slow-Rapid pattern was significantly associated with lower length z-scores of offspring (β = -0.084
se = 0.015), compared to the Moderate pattern, while the Rapid-Slow pattern was significantly associated with higher length z-scores (β = 0.083
se = 0.022), with no significant effects on other anthropometric outcomes. Similar results were also observed in the non-GDM group. However, in the GDM group, offspring of mothers with the Rapid-Slow pattern showed significantly higher weight z-scores (β = 0.093
se = 0.046), BMI z-scores (β = 0.113
se = 0.052), and risk of overweight/obesity (OR = 1.40, 95%CI: 1.11, 1.76). CONCLUSION: GWG trajectory significantly impacted offspring growth before 36 months, with different effects observed based on GDM status. GWG trajectory primarily affected offspring length in the non-GDM group, whereas earlier high weight gain appeared to increase offspring weight, BMI, and risk of overweight/obesity in the GDM group.