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

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.

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.

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.

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