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.
You need to seriously increase your flexibility down in your fetus's living quarters because, during pregnancy, your uterus grows from about the size of a tennis ball to the size of a beach ball. Relaxin relaxes the intrauterine ligaments, allowing the uterus and pelvis to expand.