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.
Progesterone is a hormone that helps prepare your body for pregnancy. It may help prevent premature birth only if you have a short cervix and youâre pregnant with just one baby. You insert it in your vagina every day starting before or up to 24 weeks of pregnancy, and you stop taking it just before 37 weeks.