Oxytocin acts on smooth muscles of our body and stimulates their contraction. In females, it stimulates a vigorous contraction of uterus at the time of child birth, and milk ejection from the mammary gland after child birth.
Prolactin regulates the growth of the mammary glands and production of milk in them.
Progesterone supports pregnancy. Progesterone also acts on mammary glands and stimulates the formation of alveoli ( sac like structures which store milk) and milk secretion.