Final answer:
Enlargement of the breasts in a newborn is due to maternal hormones during pregnancy. The increase in hormones, such as estrogen and progesterone, leads to the development and enlargement of the mammary tissue, preparing the mother for lactation and breastfeeding.
Step-by-step explanation:
Enlargement of the breasts is a finding in a newborn that is due to maternal hormones. During pregnancy, the increase in hormones, such as estrogen and progesterone, leads to further development of the mammary tissue and enlargement of the breasts. This prepares the mother for lactation and breastfeeding.