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.
Toward the end of your pregnancy you'll experience a surge in the hormone relaxin, which helps your ligaments become stretchy for childbirth. Relaxin can also loosen your pelvic joint, and even cause it to separate a bit. It's common to feel pain near your pubic bone, and you may also feel like your legs are unstable.