Abstract
Breast tissue in newborn infants is considered to be physiologic and mainly related to exposure to maternal hormones in utero or through breast-feeding. However, controversy exists as to whether breast tissue in later infancy is under the influence of endogenous hormones. Children at 2–4 mo of age have a surge of reproductive hormones, including estradiol, which may affect the mammary gland. In a prospective cohort study of 1126 healthy, 3-mo-old infants, breast tissue size and reproductive hormones were measured. We found that palpable breast tissue (diameter ≥3 mm) is a common physiologic condition present in 78.9% of children, significantly more frequent (p < 0.001) and larger (p < 0.001) in girls than in boys. Girls had significantly higher median estradiol levels than boys (30.0 versus 21.0 pmol/L, p < 0.001). In a multiple regression model including breast tissue size given as quartiles as the dependent variable and weight for gestational age, subscapular skinfold, weight at 3 mo of age and serum estradiol as independent variables, a gender difference was shown. In girls, the estradiol level was positively (p < 0.03) correlated to breast quartile. In boys, no correlations were found. Whether the stimulation of the mammary gland in infancy represents a developmental window that is of biologic significance for breast development and pathology in adulthood remains to be defined.
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Abbreviations
- WGA:
-
weight for gestational age
- SHBG:
-
sex hormone binding globulin
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Acknowledgements
The authors thank the families and the Departments of Obstetrics and Gynaecology at the University Hospital of Copenhagen for their excellent cooperation.
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Supported by the Danish Research Council (no. 9700833), Research Foundation of The Copenhagen Hospital Corporation (no. 109/00), EU-grant Envir. Reprod. Health (no. QLK4-1999-01422), and the Ville Heise Foundation.
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Schmidt, I., Chellakooty, M., Haavisto, AM. et al. Gender Difference in Breast Tissue Size in Infancy: Correlation with Serum Estradiol. Pediatr Res 52, 682–686 (2002). https://doi.org/10.1203/00006450-200211000-00012
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DOI: https://doi.org/10.1203/00006450-200211000-00012
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