Fimbriae (common pili) and flagella on the surface of bacterial cells. Left: dividing Shigella enclosed in fimbriae. The structures are probably involved in the bacterium's ability to adhere to the intestinal surface. Right: dividing pair of Salmonella displaying both its peritrichous flagella and its fimbriae.
Relaxin's peak is reached during the 14 weeks of the first trimester and at delivery. It is known to mediate the hemodynamic changes that occur during pregnancy, such as increased cardiac output, increased renal blood flow, and increased arterial compliance.
Relaxin, another hormone that messes with you during pregnancy, loosens up your ligaments and joints in preparation for birth. Even though you need the extra give only in your pelvis, the hormone works on your entire body, which means your hands and feet are affected, too. See more about Week 13 of your pregnancy.