Which hormone is responsible for the development of breast tissue during pregnancy?

The development of breast tissue during pregnancy is primarily attributed to estrogen. This hormone plays a crucial role in the maturation of mammary glands, preparing them for lactation. As the pregnancy progresses, estrogen levels rise significantly, stimulating the growth of breast tissue and enhancing the ductal system within the breasts. This prepares the breasts not only for milk production but also for the changes necessary for breastfeeding after delivery.

While other hormones such as progesterone and prolactin also play roles in breast development and lactation, it is estrogen that is most directly linked to the initial growth and development of breast tissue during pregnancy. Progesterone contributes to the development of the milk-secreting tissue, but estrogen is the primary hormone responsible for the overall breast tissue development during pregnancy. Oxytocin is more involved in the milk ejection reflex during breastfeeding rather than initial breast tissue development.