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.
Muscle strain and backache may be common during pregnancy, but many drugs that are safe for most adults can be harmful to a pregnant woman or her fetus. Flexeril, known generically as cyclobenzaprine, is a muscle relaxant most often given for treatment of injury or muscle strain. If you are pregnant, tell your doctor about your condition and about all medications you are taking before taking any additional medication to make sure it is safe for you and your baby.