Early Puberty in Internationally Adopted Girls: Hormonal and Clinical Markers of Puberty in 276 Girls Examined Biannually over Two Years

Abstract

Background and Aims: Retrospectivestudies have indicated that internationally adopted girls are at high risk of developing precocious puberty. Hypothetically, this could be due to selection bias. The aim of this study was to determine age at reaching pubertal milestones in healthy internationally adopted girls in a prospective, clinical study. Methods: A longitudinal cohort study including 276 randomly recruited internationally adopted girls. At baseline, age ranged from 4 to 13 years. Participants were followed with biannual examinations over a period of 2 years. Examinations included height, weight, Tanner staging, blood sampling and bone age assessment. Age distribution at entering pubertal stages B2–B5 (breast development), PH1–PH5 (pubic hair development) and menarche was estimated by probit analysis. Data were compared to a reference population of Danish-born girls, studied cross-sectionally. Results: Mean age at B2+ was 9.5 years (95% prediction interval 7.1–12.0 years) and mean age at menarche was 12.1 (10.2–14.0) years in adopted girls, which was significantly lower compared to the reference group (p < 0.0003). 16% of adopted girls entered stage B2 before 8 years of age. The puberty-related rise in LH, FSH and estradiol was detected at earlier ages in adopted girls compared to the reference group. Conclusion: Internationally adopted girls have a significantly higher risk of precocious pubertal maturation compared to Danish-born girls.

Hypothesis: exposure to endocrine‐disrupting chemicals may interfere with timing of puberty

“…However, in most cases, no underlying aetiology of PP can be found. A particularly high frequency of PP was found among foreign adopted girls (Proos et al, 1991;Krstevska-Konstantinova et al, 2001;Teilmann et al, 2009) and to a lesser extent, also among immigrant children (Teilmann et al, 2002). Both adopted and immigrated children experience profound changes in lifestyle.…”

Adolescent Undernutrition: Global Burden, Physiology, and Nutritional Risks

“…The biology of this phenomenon needs to be better understood. In a more recent study, adopted girls in Denmark entered puberty earlier (by about 1.3 years) than the Danish born girls, and they did not achieve the same height but weighed the same as their local counterparts [29]. …”

International Adoption, “Early” Puberty, and Underrecorded Age

“…Internationally adopted children appear to reach puberty at a relatively young age 1 and to have a high risk of early puberty including very early or precocious puberty (PP), that is, pubertal development at ,8 years of age for girls and at ,9 years of age for boys. 2,3 However, there can be uncertainty over the chronological age of adopted children, raising the possibility that the seemingly elevated risk of early puberty is due to some children having a significantly underrecorded age, perhaps of up to 2 years or more.…”

“…1 Nonetheless, most researchers have tended to discount underrecorded age as a systemic explanation of the elevated risk of early puberty in favor of theories that assume that, in most cases at least, they are dealing with a genuine diagnosis. However, I would argue that some of the puzzling findings uncovered by the research, on age at adoption, catch-up rates, final height, and height after treatment to delay puberty, can be explained by underrecorded age.…”