Timing of puberty and physical growth in obese children: a longitudinal study in boys and girls

Objective: To assess whether puberty and physical growth vary in obese when compared to normal-weight children.

Methods: One hundred obese pre-pubertal children (44 boys; mean age (±SD): 9.01 ± 0.62 years; 56 girls; 8.70 ± 0.57 years) were compared to 55 normal-weight controls (27 boys; 9.17 ± 0.26 years; 28 girls; 8.71 ± 0.62 years). All study participants were followed prospectively with 6-monthly follow-up visits. At each study visit, height, weight, body mass index (BMI) and pubertal stage were assessed.

Results: Obese children entered puberty and achieved later stages of puberty earlier than controls (onset of puberty: boys: 11.66 ± 1.00 vs. 12.12 ± 0.91 years, P = 0.049; girls: 9.90 ± 0.78 vs. 10.32 ± 1.70, P = 0.016; late puberty: boys: 13.33 ± 0.71 vs. 14.47 ± 1.00 years, P < 0.001; girls: 11.54 ± 0.99 vs. 12.40 ± 1.02, P = 0.001). Pre-pubertal BMI standard deviation score (SDS) was inversely associated with both age at the onset of puberty (β = -0.506, P < 0.001) and age at late puberty (β = -0.514, P < 0.001). Obese children also showed an earlier age at peak height velocity (PHV) (boys: 12.62 ± 0.82 vs. 13.19 ± 0.96 years, P = 0.01; girls: 11.37 ± 0.89 vs. 12.77 ± 0.76, P < 0.001) and a lower PHV (boys: 7.74 ± 1.49 vs. 9.28 ± 1.64 cm year(-1) , P < 0.001; girls: 7.60 ± 1.64 vs. 8.29 ± 1.03, P = 0.03). Height SDS progressively declined over the study period in the obese group (P for trend <0.001), whereas there were no significant changes in the control group (P for trend = 0.5).

Conclusions: Obese boys and girls presented an earlier onset of puberty and completion of puberty and an impaired height gain during puberty.