The umbilical cord clamp
				Ziegler (1922) described the need for clamping the cord as follows:
					"The primary object of ligating or clamping the cord is, of course, to prevent hemorrhage; and while it is true that hemorrhage would rarely occur even were the cord not compressed, especially after the establishment of respiration, the fact is that hemorrhages have occurred and even with fatal termination.  In fifteen years I have had two cases of secondary hemorrhage from the cord which were all but fatal.  It is likely, therefore, that some form of compression will always be regarded as necessary."
			Note Ziegler's remark that hemorrhage would rarely occur even were the cord not compressed, especially after the establishment of respiration.  This corroborates the observation of Gunther (1957) that cessation of placental transfusion was often apparent after a main reservoir had been filled.  This reservoir would appear to be the capillary system surrounding the alveoli of the lungs (Jäykkä 1958, Mercer & Skovgaard 2002).
		Placental blood is respiratory blood.  Research by Redmond et al. (1965) provided dramatic evidence that the infant's first breath redirects blood from the placenta to the lungs.
	Ziegler's paper described several new devices tor use in obstetrics, of which the clamp was one, a replacement for the earlier technique of tying the cord.   That not all obstetricians clamped or tied the cord at that time can be inferred from his next statement:
						"To those members of the profession whose custom it is to clamp the cord, this clamp will make its strongest appeal."