The preventive effect of breast-feeding for longer than 6 months on early pubertal development among children aged 7–9 years in Korea

Abstract

Objective: The present study was performed to investigate whether breast-feeding is associated with early pubertal development among children 7-9 years old in Korea. Design: Children were divided into those who did and did not receive breastfeeding for 6 months or longer in accordance with the recommendations of the WHO. Pubertal status was determined by clinical examination using Tanner staging. Setting: Prospective observational study. Subjects: We conducted a follow-up study of children aged 7-9 years in 2011 who had taken part in the Ewha Birth & Growth Cohort study. Results: Fifty (22·8 %) of the total of 219 children were in early puberty, with the proportion being slightly higher for girls (24·1 %) than boys (21·4 %). Children who had entered early puberty were taller, weighed more and had a higher concentration of insulin-like growth factor 1. Moreover, the change in weight Z-score from birth to follow-up was significantly lower in children who were breast-fed than in those who were not (weight Z-score change: 0·32 (SD 1·59) v. 0·77 (SD 1·61), respectively, P = 0·04). Comparison of breast-feeding by puberty status indicated a preventive association with early puberty in children who were breast-fed for 6 months or longer (OR = 0·37; 95 % CI 0·18, 0·74). This association remained significant after adjustment for relevant covariates.Conclusions: These results demonstrate a beneficial association between breastfeeding and early pubertal development, especially in those breast-fed for 6 months or longer. The study suggests that interventions would need to start early in life to prevent early pubertal development.

Long-term effects of the SLC2A9 G844A and SLC22A12 C246T variants on serum uric acid concentrations in children

“…By 2016, the follow-up of children aged 9 years had been completed. The methodology of the cohort study has been reported elsewhere [ 20 , 21 ]. In this study, two SNPs were genotyped in the subjects who were followed up at least once.…”

Which Diet-Related Behaviors in Childhood Influence a Healthier Dietary Pattern? From the Ewha Birth and Growth Cohort

“…About 30% of all possible subjects agreed to participate in the study [ 16 ]. A detailed description of the cohort composition, including methodology, has been published elsewhere [ 17 ]. Through follow-up at 7 or 9 years of age, a diet-related questionnaire survey was performed using a food frequency questionnaire (FFQ) and questions related to dietary habits.…”

Nutritional Determinants of the Timing of Puberty

“…Although the study estimates were adjusted for potential confounding by maternal and family characteristics, the interpretability of the results is limited because adjustment also included body mass index (BMI) in childhood, a variable that could be a mediator in the causal pathway. In a study of 219 Korean children, after adjusting for age and sex, those who were breastfed for ≥6 months had lower odds of reaching a Tanner stage ≥2 at 9 years of age compared with children who were breastfed for <6 months (58). In a prospective investigation of 994 Filipino girls, every month of exclusive breastfeeding was associated with a 6% lower probability of menarche over the followup period after adjusting for socioeconomic, maternal, and birth characteristics (3).…”

“…Second, many of the studies had large losses to follow-up, which could result in selection bias if both infant feeding practices and pubertal stage affected retention. Third, most studies were restricted to girls, which hinders the generalizability of findings; in addition, some of the investigations that included both girls and boys did not present results stratified by sex (58). Fourth, observational studies are subject to residual confounding, and some of the analyses (48) may have incurred overadjustment bias.…”