Prolactin, maternal oestrogens, and breast development in the newborn

Area of Science:

• Endocrinology
• Neonatal development
• Human physiology

Background:

• Maternal hormones are thought to influence fetal development.
• The role of endocrine activity in neonatal breast growth requires further elucidation.

Purpose of the Study:

• To investigate the influence of maternal oestrogens on fetal breast development.
• To examine the relationship between maternal and infant hormone levels and neonatal breast size.

Main Methods:

• Maternal urinary oestriol excretion and plasma oestriol concentrations were measured.
• Cord venous plasma oestradiol and oestriol concentrations were analyzed.
• Neonatal breast size was correlated with maternal and infant hormone levels, including prolactin.

Main Results:

• A weak positive association was found between maternal oestriol excretion and neonatal breast size, potentially confounded by birthweight.
• Infant prolactin concentrations showed a strong association with breast size in mature neonates aged 5-7 days.
• Breast tissue development postnatally was observed in preterm infants, with elevated prolactin levels later in the first weeks of life.

Conclusions:

• Early neonatal breast development appears to be more influenced by the infant's endocrine activity, particularly prolactin, than by maternal endocrine factors.
• Further research is needed to fully understand the complex interplay of hormones in neonatal breast growth.