This systematic review and meta-analysis examined the associations between obesity and puberty timing based on scientific evidence. Eight electronic databases were searched up to February 2017 for eligible studies, and two reviewers screened the articles and extracted the data independently. A total of 11 cohort studies with 4841 subjects met the inclusion criteria. Compared with the group of normal-weight girls, the obese group had more girls with menarche (RR: 1.87, 95% CI: 1.59-2.19, 2 studies). The number of girls with early puberty was significantly higher in the obese group than the normal weight group (RR: 2.44, 95% CI: 1.32-4.52, 5 studies). However, no differences were detected between girls who were obese or normal weight at age of menarche (WMD: -0.53 years, 95% CI: -1.24-0.19, 2 studies). There is no consistent result in the relationship between obesity and timing of pubertal onset in boys. Obesity may contribute to early onset of puberty in girls, while in boys, there is insufficient data. Given the limited number of cohort studies included in this meta-analysis, high-quality studies with strong markers of puberty onset, as well as standardized criteria for defining obesity are needed.
Keywords: childhood obesity; meta-analysis; puberty timing; systematic reviews.