Does breastfeeding protect against central precocious puberty?

Puberty that begins too early is not just a biological detail. It disrupts children's psychosocial balance and often heralds increased risks in adulthood: diabetes, cardiovascular disease, cancer and gynecological or obstetric disorders. Today, central precocious puberty (CPP), triggered by premature activation of the hypothalamic-pituitary-gonadal axis, is a growing concern. "The age at which puberty begins has gradually decreased over the past few decades, accompanied by an increasing incidence of CPP," Dr. Yunsoo Choe, a pediatrician at Hanyang University Guri Hospital, and his colleagues note in JAMA Network Open. Given this context, the researchers sought to discover whether a factor as early and modifiable as infant feeding could influence this trajectory.To answer this question, the researchers used the National Health Insurance Service database in South Korea. Their retrospective study included 322,731 children born between 2007 and 2010, followed from birth until age 9 for girls and 10 for boys. Feeding methods during the first four to six months of life—exclusive breastfeeding, formula feeding, or mixed feeding—were reported by parents during a health checkup. Adiposity was measured at 66–71 months, and PPC was defined by a physician's diagnosis accompanied by gonadotropin-releasing hormone (GnRH) agonists.Protective effect of exclusive breastfeedingAmong exclusively breastfed children, the prevalence of PPC was 2.8%, compared to 3.0% among those who were formula-fed or mixed-fed. After adjustment, the risk of PPC was significantly increased among children who were not breastfed at all:Formula-fed boys: aHR (adjusted hazard ratio) 1.16 (95% CI 1.10–1.21, p < 0.001);mixed-fed boys: aHR 1.14 (95% CI 1.07–1.20, p < 0.001);formula-fed girls: aHR 1.60 (95% CI 1.24–2.06, p < 0.001);mixed-fed girls: HRa 1.45 (95% CI 1.07–1.97, p < 0.001)."Children who were not exclusively breastfed during the first 4 to 6 months had a higher probability of developing central precocious puberty, regardless of sex," the authors write. Mediation analysis shows that prepubertal overweight or obesity explained 7.2% of this association in boys (95% CI [bootstrap] 4.5–12.1) and 17.8% in girls (95% CI [bootstrap] 6.6–30.0). Low birth weight (aHR for boys 1.99 [95% CI 1.21–3.26]; girls 1.17 [95% CI 1.05–1.30]) and maternal age 35 years or older (aHR for girls 1.43 [95% CI 1.24–1.66]) were also independent risk factors.Biological mechanisms yet to be clarifiedBeyond the effect on weight, the researchers suggest several pathophysiological possibilities. "Although the concentration of IGF-1 in formula milk is lower than that of breast milk, formula-fed infants tend to have higher circulating concentrations of IGF-1 at 3 months of age," they note. IGF-1 is associated with accelerated linear growth and may "stimulate sex steroid production and GnRH secretion," thereby promoting earlier pubertal maturation.The gut microbiota is another avenue. "Breast milk contains beneficial bacteria that primarily shape the infant microbiota," the authors report. Breastfed infants have more Bifidobacterium and lower microbial diversity, while those who are formula-fed have greater diversity with more Firmicutes and Proteobacteria. These differences could influence hormonal regulation and the onset of puberty.In a commentary co-published by JAMA Network Open, epidemiologist Dr. Lin Yang (Alberta Health Services and the University of Calgary) and Dr. Shengxu Li (Children's Hospitals and Clinics of Minnesota) place these findings in a broader context. "Exclusive breastfeeding during the first months of life was associated with a reduced risk of PPC in both sexes, mediated in part by prepubertal overweight," the two researchers summarized. A public health issueFor them, this study adds to the already well-documented benefits of breastfeeding—reduced infant morbidity, improved neurodevelopment, and a lower risk of obesity and diabetes in adulthood. It also encourages us to consider the prevention of childhood obesity as a key lever: physical activity, sleep and a family environment. "The disease starts early, and so does its prevention," noted Drs. Yang and Li.Like any observational study, this one does not allow strict causality to be inferred. Feeding method was reported only once, the definition of PPC was based on diagnostic codes and prescriptions, and the age of maternal menarche was not available. However, the size of the cohort, the rigour of the analyses, the stratification by sex and the confirmation of the results through sensitivity analyses reinforce its validity.PPC is not only a clinical issue; it is also a growing public health problem. Children who experience it can suffer adverse psychological effects and increased medical risk throughout their lives. However, as Drs. Yang and Li note, “exclusive breastfeeding rates remain insufficient and declining in many high-income countries, including South Korea.” Promoting breastfeeding therefore requires parental leave policies, favorable work environments, and active lactation support, the two researchers say, adding that preventing childhood obesity must remain a priority.References: Choe Y, Ryu S, Choi J, et coll. Breastfeeding, Prepubertal Adiposity, and Development of Precocious Puberty. JAMA Netw Open. 2025;8(8):e2527455. doi:10.1001/jamanetworkopen.2025.27455Yang L, Li S. Breastfeeding, Adiposity, and Precocious Puberty in Boys and Girls. JAMA Netw Open. 2025;8(8):e2527461. doi:10.1001/jamanetworkopen.2025.27461

Does breastfeeding protect against central precocious puberty?

Register for free access or login.

Related Topics

Business Topic