IBCLC Practice Exam 2025 – Complete Preparation Guide

Estrogen plays a crucial role during pregnancy, particularly in preparing the breast for lactation. One of the primary functions of estrogen is to stimulate the growth and development of the ducts within the mammary glands. These ducts are essential for the transportation of milk from the alveoli, where it is produced, to the nipple for breastfeeding.

During pregnancy, the surge in estrogen levels leads to an increase in the number and branching of these ductal structures. This growth is critical for establishing an effective milk delivery system once the baby is born. While other tissues in the body, such as fat and muscular tissue, may also respond to hormonal changes during pregnancy, the specific and immediate stimulation of ductal development in the breast is primarily attributed to estrogen's actions.

The other options do not specifically correlate with the direct effects of estrogen on mammary gland development in preparation for lactation. While fat cells and vascular tissue undergo changes during pregnancy, the primary target of the estrogen surge in the context of preparing for breastfeeding is the ductal system in the mammary glands.