Breastfeeding has previously been associated with a reduced risk of rapid weight gain in childhood and childhood obesity. Researchers investigated the relationship between the duration of breastfeeding and the timing of puberty among children. The study shows that a shorter breastfeeding period was associated with earlier puberty for boys but not for girls.
Early pubertal development is associated with the development of several diseases later in life such as type 2 diabetes, cardiovascular disease and breast and testicular cancer. Elucidating the potential causes of early pubertal development is therefore important.
“We are investigating possible reasons why some children begin puberty earlier than others, because the age at puberty has been declining and may still be declining, and we would like to help to find possible reasons for this,” says senior author Cecilia Ramlau-Hansen, Professor, Department of Public Health, Aarhus University.
Association between breastfeeding and puberty
“We know that breastfeeding can benefit the child in both the short and long term. However, few studies have examined the potential associations between breastfeeding and the child’s pubertal development. Previous studies have shown that children who are breastfed have a lower risk of rapid weight gain in childhood, and overweight boys and girls seem to reach puberty earlier than normal-weight children. We therefore investigated whether the duration of exclusive breastfeeding affects pubertal age and whether weight in childhood could be a possible association,” explains first author Julie Hvidt, Department of Public Health, Aarhus University.
Based on this link between the duration of breastfeeding and pubertal development, the researchers hypothesised that a shorter duration of exclusive breastfeeding would be associated with earlier pubertal age. The data for the study came from the Puberty Cohort nested within the Danish National Birth Cohort, which included 13,511 boys and girls. The children gave self-reported information on their pubertal development, and the mothers provided information on breastfeeding when the children were 6 months of age.
Associated only among boys
The results showed that boys tended to reach several puberty markers later for each additional month of exclusive breastfeeding. In addition, puberty markers were reached earlier among boys never breastfed compared with boys exclusively breastfed longer than 4 months. In contrast, the duration of exclusive breastfeeding was not associated with puberty among girls in the study.
“The results suggest that shorter breastfeeding is associated with earlier pubertal development among boys: the shorter the duration of exclusive breastfeeding, the earlier pubertal development. Including body mass index in childhood or weight gain in a child’s first year of life kept our results largely unchanged,” says Cecilia Ramlau-Hansen.
Julie Hvidt concludes by explaining that the findings for boys are in accordance with both the Danish Health Authority and WHO, which recommend exclusive breastfeeding for 6 months.