The obstetric clamp
    Wechsler (1912) published a brief note in the American Journal of Obstetrics and
    Diseases of Children on use of an obstetric clamp as an alternative to traditional
    ligature with a cloth tie.  On a visit to Vienna, he had witnessed use of a sterile
    hemostat clamp on the umbilical.cord.  First on his list of instructions was to wait for
    pulsations in the cord to cease before applying the clamp.

    Ten years later, Zeigler (1922) published an article on instruments used in
    obstetrics, which included a clamp used as an alternative to tying the cord.

    Dicks (1925) promoted use of a clamp to prevent infection.  Again, waiting for
    pulsations in the cord to cease was first on his list of instructions.

Postnatal placental circulation
    Haselhorst (1928, 1929) used temporary compression of the cord to measure infant
    weight changes during the course of continuing placental circulation following birth.  
    English language summaries of Haselhort's work were provided by Frischkorn and
    Rucker (1939).
References
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  1. Wechsler  BB. Umbilical clamp.  Am J Obstet Dis Women Child 1912; 60:85-6.
  2. Ziegler CE. Additions to our obstetric armamentarium.  Am J Obstet Gynecol
    1922; 3:46-53.
  3. Dicks JF. Treatment of the umbilical cord by short ligation and the use of a
    clamp. Am J Obstet Gynecol 1925 Nov; 10(5):706-8. Discussion pp739-40.
  4. Haselhorst G. Uber Art und Dauer der Blutstromung in den
    Nabelschnurgefassen post partum. Z Geburtshilfe Gynakol 1929; 96:487-
    499 (Zeitschrift für Geburtshilfe und Gynäkologie).
  5. Haselhorst G (1928a) Zum plazentaren Kreislauf unter der Geburt. Zeitshrift
    fur Gegurtshulfe und Gynakologie 95:32-42.
  6. Haselhorst G (1928b) Zum plazentaaren Kreislauf unter der Geburt. Zeitshr.
    f. Geb. u Gynakol. 95:224-233.
  7. Frischkorn HB , Rucker MP (1939) The relationship of the time of ligation of
    the cord to the red blood count of the infant. Am J Ostet Gynecol 38:592-594.

(in progress)
Williamson, A. C., Taylor, J. V. (1924) J. Amer. med. Ass. 82, 1107. Cited by
Redmond et al. (1965)