Timing of thelarche and menarche and temporal growth trends in internationally adopted girls in Spain: a prospective cohort study

Introduction: This prospective observational study evaluated the age at thelarche and menarche in internationally adopted girls in Spain and analyzed height and body mass index trends at these pubertal milestones. Material and methods: The study included 102 healthy girls adopted in Spain between 1998 and 2008 from Russia/Ukraine (38), China (34), India/Nepal (17), and Latin America (13). Growth and pubertal development were assessed using standardized procedures. Families were trained to recognize thelarche and menarche, allowing clinical confirmation and anthropometric evaluation. Measurements obtained at adoption, thelarche and menarche were compared with WHO Child Growth Standards, and z-scores were calculated. Pearson correlation coefficients were used to assess associations. Results: Mean age at adoption was 3.5 years. Girls from India/Nepal and Latin America were adopted later, whereas those from China were adopted younger. At adoption, the cohort showed height delay with greater deficits in height than weight. Mean age at thelarche was 9.7 years, occurring earlier in girls from Latin America and India/Nepal and later in girls from China. A significant negative correlation was found between age at adoption and age at thelarche (r = -0.43, p < 0.001), indicating that later adoption was associated with earlier pubertal onset. Height normalized at thelarche, reflecting marked catch-up growth, and no association was observed between anthropometric measures at adoption and at thelarche. Mean age at menarche was 11.7 years, with earlier onset in girls from Latin America and India/Nepal and later onset in girls from China. Age at adoption was also negatively correlated with age at menarche (r = -0.48, p < 0.001). Although menarche occurred earlier in girls adopted later, growth patterns at this pubertal milestone were unrelated to age at adoption. Conclusions: Internationally adopted girls in Spain experienced early thelarche and menarche, particularly when adopted at older ages, independent of later growth patterns.