During what week of pregnancy does the prolactin level significantly increase?

Prolactin levels begin to rise significantly during pregnancy to support lactation and prepare the body for breastfeeding after childbirth. This increase can be attributed to hormonal changes, particularly the influence of estrogen and progesterone, which stimulate the anterior pituitary gland to produce more prolactin.

Typically, prolactin levels start to increase around the fifth week of pregnancy. At this early stage, the developing placenta is also starting to function, contributing to the hormonal environment that promotes the increase of prolactin. This rise in prolactin continues throughout the pregnancy and peaks toward the end, ensuring that adequate levels are present for milk production after delivery.

Options representing the first week, tenth week, and fifteenth week do not align with the timeline of significant prolactin increase in the context of normal pregnancy physiology. This crucial timing highlights the importance of early hormonal changes in supporting fetal development and preparing the mother's body for postnatal care.