Birth weight and prepubertal growth trajectory had a combined effect on pubertal initiation in girls

Aim: Most studies of prepubertal weight and puberty have not used continuous or long follow-up periods. We explored the effect that birth weight and growth trajectories from 0-9 years of age had on starting puberty.

Methods: Data were obtained from 1510 children in Tianjin, China, who were born in 2013 and selected by cluster random sampling. Information on pubertal status was collected by parent-reported questionnaires and up to 14 anthropometric measurements were obtained from physical examinations. A group-based trajectory model was applied to fit the growth trajectories. Cox regression and log-binomial regression were used for association analyses.

Results: After exclusions, we studied 1164 children (50.9% girls) up to a mean age of 9.6 years. Girls with a low birth weight or low-stable growth trajectories were less likely to have started puberty, while those with macrosomia or high-stable growth trajectories had a higher risk of having started puberty. Combined analyses showed that the risk of pubertal initiation for girls with a normal birth weight and low-stable trajectories was 0.76. It was 1.42 for those with macrosomia and high-stable trajectories. Similar results were not found in the boys.

Conclusion: It is important that pubertal initiation studies investigate growth over the life course.