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.
If you're getting back pain early on in pregnancy, relaxin's likely to be the cause (Murray and Hassall 2014, NCCWCH 2008) . It's common to have lower back pain in the first trimester (Murray and Hassall 2014, Vermani et al 2010) .ack pain is very common in pregnancy. Between a half and three quarters of pregnant women have it at some stage (Bastiaenen et al 2008, Klemetti et al 2011, Mota et al 2015) .