How does the body respond to fertilization?

When fertilization occurs, the body initiates a series of biological changes to support the establishment and maintenance of early pregnancy. One of the critical responses is the maintenance of elevated hormone levels, particularly progesterone and estrogen. These hormones are crucial in ensuring that the uterine lining is adequately prepared to receive and support the developing embryo.

After fertilization, the embryo begins to produce human chorionic gonadotropin (hCG), which signals the corpus luteum to continue its production of progesterone. This is essential because progesterone helps to maintain the uterine lining, preventing menstruation and creating a suitable environment for the growing embryo. This sustained hormonal support is vital during the first trimester until the placenta takes over the production of hormones necessary for maintaining pregnancy.

In contrast, if fertilization does not occur, the menstrual cycle resumes, the corpus luteum degenerates, and hormone levels fluctuate as the body prepares for the next cycle. Therefore, the correct response reflects the body’s preparation for early pregnancy through the maintenance of hormone levels necessary for sustaining the developing embryo.