Which hormone plays a crucial role in modifying ligamentous structures during pregnancy?

Relaxin is a hormone that is pivotal during pregnancy as it facilitates the modifications of ligamentous structures to accommodate the growing fetus. This hormone is primarily secreted by the ovaries and the placenta. Its primary function is to relax the pelvic ligaments and soften the cervix in preparation for childbirth. By increasing the laxity of ligaments and connective tissues, relaxin allows for greater flexibility and expansion of the pelvis, which is essential during labor and delivery.

It also plays roles in modulating the mother’s cardiovascular and renal systems to support the increased demand from the developing fetus. This adjustment helps maintain stability and function in the woman's body as it undergoes substantial changes during pregnancy.

The other hormones listed do not have the same specific role in modifying ligamentous structures during pregnancy. For example, human chorionic gonadotropin primarily supports the early stages of pregnancy, corticosteroids are involved in various stress responses and metabolism, and testosterone is more associated with male development and does not have a significant role in modifying connective tissues during pregnancy.