Certified Breastfeeding Counselor (CBC) Practice Exam 2026 - Free CBC Practice Questions and Study Guide

During Lactogenesis 1, the hormone responsible for causing an increase in alveoli is Progesterone. Progesterone plays a crucial role during pregnancy in preparing the breast tissue for lactation. It stimulates the growth and development of the alveoli, the small sacs within the breast where milk is produced. As the mammary glands develop more alveoli under the influence of progesterone, the breast tissue gets ready for milk production postpartum. This hormone helps in laying the foundation for successful breastfeeding after childbirth.

While oxytocin, insulin, and prolactin are important hormones in the breastfeeding process, they do not specifically cause an increase in alveoli during Lactogenesis 1. Oxytocin is responsible for milk ejection or the let-down reflex, insulin helps regulate blood sugar levels but is not directly involved in alveoli growth, and prolactin stimulates milk production but does not induce alveoli development during Lactogenesis 1.