What hormonal secretion causes breast changes during pregnancy?

Breast changes during pregnancy are primarily driven by the hormonal secretions of estrogen and progesterone. These two hormones play crucial roles in preparing the body for lactation and supporting fetal development.

Estrogen promotes the growth of breast tissue, including the development of the mammary ducts. It contributes to increased blood flow to the breasts and the overall enlargement and sensitivity that many women experience during pregnancy. Progesterone complements this process by stimulating the formation of glandular tissue and preparing the breasts for milk production.

Together, these hormones cause not only the physical changes to the breasts, such as fullness and tenderness, but also initiate the complex process that prepares the body for breastfeeding after delivery. The significant hormonal shifts during pregnancy specifically highlight the essential roles of estrogen and progesterone in breast development and function.