Breast feeding and timing of puberty in boys and girls: A nationwide cohort study

Abstract

Background Breast feeding has been associated with improved infant health, but its impact on pubertal timing remains uncertain, particularly in boys. Objective The objective of this study was to investigate the association between duration of breast feeding and pubertal timing in boys and girls. Methods This population‐based cohort study included 13 511 boys and girls from the Puberty Cohort nested within the Danish National Birth Cohort. The children gave half‐yearly, self‐reported information on pubertal development through questionnaires (Tanner stages, age at menarche, first ejaculation, voice break, axillary hair growth, and acne). Information on breast feeding was provided by the mothers when the children were 6 months of age. We estimated mean differences (in months) in age at attaining each pubertal marker and for overall timing of puberty (combined estimate) for every additional month of exclusive breast feeding. Furthermore, we estimated differences in pubertal age when comparing children never exclusively breastfed and exclusively breastfed <4 months using children exclusively breastfed ≥4 months as reference. In sub‐analyses, we further adjusted for infant weight gain and childhood BMI at 7 years to investigate whether these variables mediated the association. Results Boys tended to reach pubertal markers later for every additional month of exclusive breast feeding (combined estimate: 0.2 (95% confidence interval [CI] 0.0, 0.4 months). Never exclusively breastfed boys reached pubertal markers earlier than the boys exclusively breastfed ≥4 months (combined estimate: −4.1 (95% CI −6.7, −1.6) months). Boys exclusively breastfed <4 months also reached pubertal markers earlier than those never exclusively breastfed but with smaller differences. In girls, duration of breast feeding was not associated with pubertal development. When including infant weight gain or childhood BMI, the results remained essentially unchanged. Conclusions Shorter duration of exclusive breast feeding was associated with earlier pubertal development in boys but not in girls.

Diet and Nutrients Intakes during Infancy and Childhood in Relation to Early Puberty: A Systematic Review and Meta-Analysis

“…Briefly, 22 articles investigated the association between childhood diet or nutrients and early puberty. In addition, six articles [ 16 , 21 , 22 , 23 , 24 , 25 ] provided the effects of breastfeeding duration in infancy on the timing of menarche and breast development. Among the included studies, five were cross-sectional one was a case-control study [ 26 ], and 22 were cohort studies.…”

“… Forest plot of the association between breastfeeding duration in infancy and early menarche onset [ 21 , 22 , 23 , 24 ]. …”

The Role of Pediatric Nutrition as a Modifiable Risk Factor for Precocious Puberty

“…In a recent population-based cohort study in 13,511 boys and girls, a shorter duration of breastfeeding was associated with earlier pubertal development in boys but not in girls. Specifically, boys who were never breast-fed attained pubertal markers earlier (~4.1 months) than boys exclusively breastfed for at least four months [129]. In girls, the duration of breastfeeding was not associated with pubertal development [129].…”

“…Specifically, boys who were never breast-fed attained pubertal markers earlier (~4.1 months) than boys exclusively breastfed for at least four months [129]. In girls, the duration of breastfeeding was not associated with pubertal development [129].…”

Is age of menarche directly related to vitamin D levels?

“…Genetic factors are major determinants of age at menarche but other environmental factors such as exposures to endocrine‐disrupting chemicals (Buttke et al, 2012), decline of breastfeeding (Hvidt et al, 2021), specific dietary intake (Ramezani Tehrani et al, 2013; Wiley, 2011) and childhood overweight/obesity (Al‐Awadhi et al, 2013) have been suggested to play a significant role in the decline of age at menarche. Vitamin D may contribute to the timing of menarche through musculoskeletal development as body size measures have been associated with early menarche (Freedman et al, 2002; Lindgren, 1978; Morrison et al, 1994).…”