Modern pelvimeter, based centre design of a vernier calliper, but with extended handles, steel, by Rizzoli, Italy, circa 1930

A pelvimeter is a measuring device used by obstetric physicians. This steel pelvimeter externally measured the pelvis and assessed the size of the birth canal to assess how far along a labour was. The pelvimeter opens and the distance between the two prongs is read from a sliding scale. Obstetrics is the branch of medicine dealing with the care of pregnant women, childbirth and the period of recovery immediately afterwards.