Aim
To evaluate changes in body mass index (BMI) in girls during and after treatment for idiopathic central precocious puberty (iCPP).

Methods
We studied 123 girls receiving gonadotropin-releasing hormone analogue (GnRHa)treatment for iCPP from 2009 to 2019. Pubertal and anthropometric measurements were monitored at routine clinical visits. BMI standard deviation scores (SDS) were estimated at baseline and followed in two stages from baseline to end of treatment (median 18.9 months) and from end of treatment to end of follow-up (median 18.2 months). The influence of baseline BMI SDS and the frequency and dose of treatment was evaluated using BMI trajectories and latent class mixed models.

Results
The median age at treatment initiation was 8.5 years. The median BMI SDS at baseline was 0.7, corresponding to a median BMI of 17.4 kg/m2. Overall, no changes in BMI SDS were observed during treatment. According to baseline BMI subgroups, an increasing trend in BMI trajectories during treatment was observed for girls in the lowest BMI group. After treatment, most girls maintained stable BMI levels.

Conclusion
Our retrospective study did not provide evidence that GnRHa treatment for iCPP had a significant impact on BMI trajectories in girls.