The Association of Maternal Pre-Pregnancy Overweight with Childhood BMI Trajectories and Blood Pressure

Background: Childhood high blood pressure (HBP) represents a significant risk for long-term cardiovascular health. However, the role of body mass index (BMI) trajectories from birth in shaping early-life blood pressure (BP) remains poorly understood. Methods: Data derived from a prospective birth cohort comprising 886 children (433 boys), followed from maternal pregnancy to a mean age of 9.11 years (SD = 0.71), were analyzed. Group-based trajectory modeling (GBTM) was used to identify distinct childhood BMI trajectories. Binomial regression models were applied to examine the associations among maternal pre-pregnancy overweight, childhood BMI trajectories, and the risk of HBP. Mediation analysis was used to examine the potential modulating role of BMI trajectories in the association between maternal pre-pregnancy overweight and childhood HBP. Results: Five distinct BMI trajectories were identified. Children in the “persistent overweight” (RR = 2.52, 95% CI: 1.50–4.26, p < 0.001) and “persistent obesity” (RR = 3.34, 95% CI: 1.76–6.36, p < 0.001) trajectories demonstrated significantly increased risks of HBP (The “stable normal weight” group, RR = 1). Mediation analysis revealed that BMI trajectories were associated with the linkage between maternal pre-pregnancy overweight and offspring HBP, with an indirect effect size of 0.029 (95% CI: 0.017–0.040), accounting for 34.9% of the total effect (p < 0.05). Furthermore, among children exposed to maternal pre-pregnancy overweight, those in the persistent overweight (RR = 3.35, 95% CI: 1.57–7.12, p < 0.001) and persistent obesity (RR = 4.02, 95% CI: 1.60–10.08, p < 0.001) trajectories exhibited particularly strong associations with HBP. Conclusions: Maternal pre-pregnancy overweight was linked to the elevated risk of childhood HBP, and childhood BMI trajectories may be associated with the linkage.