CAUSES, COURSE AND TIIEATMENT OF NORMAL BIRTH 59 



inducing birth-parturitio. Parturition is a physiological process, 

 which may take place without unfavorable sequels for mother 

 and foetus, yet may produce many organic changes, which, iu 

 themselves normal, predispose to diseases and disturbances ; 

 therefore, to keep away evil influences, a prophylaxis is only 

 successful where a thorough knowledge of the changes and 

 mechanism of parturition exists. As the end of gestation 

 approaches, certain phenomena announce the birth of the 

 young animal. 



What causes birth to occur at a definite time ? 



Many theories are offered in explanation. Some believe 

 that the developed foetus acts as a foreign body;' others that 

 the fatty degeneration of the epithelium of the placenta plays 

 an important role ; again, others base their hypothesis upon a 

 certain analogy existing between stomach, rectum and bladder. 

 The latter organs, which serve as a reservoir, by the accumu- 

 lation of their contents expand the contractile walls to an 

 extent resulting eventually in relaxation of the sphincter and 

 periodic evacuation. In the same manner the enlarging foetus 

 causes a relaxation of the uterine sphincter, the uterine walls 

 contract and expel the foetus (St. Cyr and Violet). 



Smith (1848) identified physiological processes with 

 oestrum and parturition. 



Brown-Sequard alludes to the fact that the excitability of 

 the uterus increases with advancing pregnancy; the presence 

 of carbon dioxide in the maternal circulation, according to him, 

 acts as a powerful excitant, producing uterine contractions. 



Obernier combines the theories of different authors, and 

 says: "Each period of menstruation excites uterine contrac- 

 tions, the tenth one sufficient to produce expulsions, the 

 uterine nerves being at that time in a hyperassthetic state." 

 It is his opinion that the cause of birth in man is found in the 

 occurrence of the tenth menstrual fluxion (Kehrer). 



Franck was of the opinion that the same conditions 

 prevail in the lower animals. He also believed that the acute 

 genital hypersemia of oestrum is identical in the causation of 

 labor pains. 



