Associations of growth trajectories from birth to two years of age with adolescent blood pressure: the mediating role of current BMI in the follow-up of an antenatal micronutrient supplementation trial.

Greater and rapid BMI and weight-for-length growth trajectories from birth to age two were statistically associated with elevated adolescent blood pressure and BP percentiles.

• Adjusted mean differences in adolescent BP ranged from 2.32 to 5.29 mmHg across trajectory groups
• Associations were observed for both systolic and diastolic BP as well as BP percentiles
• Group-based trajectory modeling was used to identify distinct early-life weight-, length-, BMI-, and weight-for-length z-score trajectories
• Measurements were taken at birth and at 1, 3, 6, 9, 12, 18, and 24 months of age

Adolescent BMI mediated a substantial portion of the association between early-life growth trajectories and systolic blood pressure, but not diastolic blood pressure.

• Adolescent BMI mediated up to 85% of the association between rapid adiposity trajectories and systolic BP
• The mediating effect of adolescent BMI was not statistically significant for diastolic BP
• General causal mediation analysis was used to estimate natural indirect effects and corresponding proportions mediated
• This differential mediation pattern suggests distinct pathways underlie systolic versus diastolic BP elevation in adolescence

Among 1388 enrolled infants, 741 were successfully followed up in adolescence for blood pressure measurement.

• The study was conducted as a prospective birth cohort in rural China
• Of the 741 adolescent participants followed up, 60.9% were male
• Mean age at adolescent follow-up was 11.26 years (SD 0.57)
• The cohort originated from a follow-up of an antenatal micronutrient supplementation trial (ISRCTN08850194, retrospectively registered December 14, 2006)
• Adolescent blood pressure was measured and converted into percentiles

The study identified distinct growth trajectory groups for weight, length, BMI, and weight-for-length z-scores from birth to two years of age.

• Group-based trajectory modeling was applied to repeated measurements taken at birth and at 1, 3, 6, 9, 12, 18, and 24 months
• Four separate trajectory types were modeled: weight, length, BMI, and weight-for-length z-scores
• Trajectories characterized by greater and more rapid growth were those most strongly associated with elevated adolescent BP

Adolescent BMI did not fully explain the association between rapid early-life growth and elevated adolescent diastolic blood pressure, suggesting pathways independent of later childhood weight.

• The mediation analysis showed no significant natural indirect effect of adolescent BMI on the trajectory-diastolic BP association
• This finding implies that interventions within the first 1000 days may be critical for lifelong cardiovascular health beyond managing later childhood weight
• The incomplete mediation, especially for diastolic BP, points to biological mechanisms set in early infancy that are not captured by adolescent BMI