A client in latent phase of labor for the past 12 hours is requesting medication to help her rest.

The correct answer is choice B. Prolactin.

Choice A reason:

Estrogen. Estrogen is a hormone that plays a role in the development of the mammary glands and the ductal system during pregnancy. However, estrogen does not directly produce milk.

In fact, high levels of estrogen during pregnancy inhibit milk secretion by blocking prolactin. Therefore, estrogen is not the hormone necessary for milk production. • Choice B reason:

Prolactin. Prolactin is the hormone responsible for the production of breast milk. Prolactin is secreted by the pituitary gland in response to suckling or nipple stimulation. Prolactin levels rise during pregnancy and peak after delivery, when the sudden drop in estrogen and progesterone allows prolactin to take over and initiate lactation. Therefore, prolactin is the hormone necessary for milk production. • Choice C reason:

Progesterone. Progesterone is a hormone that also contributes to the development of the mammary glands and the alveoli during pregnancy. However, like estrogen, progesterone does not directly produce milk. Progesterone also inhibits milk secretion by blocking prolactin during pregnancy. Therefore, progesterone is not the hormone necessary for milk production. •

Choice D reason:

Lactogen. Lactogen is not a hormone, but a general term for any substance that stimulates lactation. There are different types of lactogens, such as human placental lactogen (hPL), which is produced by the placenta during pregnancy and has some lactogenic effects on the mammary glands. However, hPL is not the main hormone responsible for milk production. That role belongs to prolactin. Therefore, lactogen is not the hormone necessary for milk production.