72 



OBSTETRICS. 



ciple, that this sort of labour is nearly as easy and as natural as 

 that by the vertex, and affirmed, that out of seventy-two cases of 

 this kind, forty-two were delivered by the unassisted efforts of the 

 female, without danger either to mother or child. They are there- 

 fore included under the head of Natural Labour. 



The causes of face presentations are obscure, and have been 

 variously described by authors. Some suppose that they are caused 

 by the inclination or obliquity of the foetus itself, rather than of the 

 organ which contains it. Madame Lachapelle attributes them to the 

 circumstance that the anterior obliquity of the womb being very 

 common, the weight of the occiput must in such cases prevent the 

 chin from being applied to the breast ; and must bring the mento- 

 bregmatic diameter into parallelism with the sacro-pubic diameter, 

 from the very commencement of the labour. Paul Dubois thinks 

 they are primitive, and probably produced by the active movements 

 of the foetus itself, and the following is his explanation. " At any 

 time during gestation, the chin may depart from the breast ; if the 

 foetus retains this position till the end of pregnancy, it becomes per- 

 manently fixed in it at the commencement of labour, by the rupture 

 of the membranes, and the contractions of the uterus." 



By most authors, obliquity of the uterus has been looked upon as 

 the principal cause of face presentations. If at the commencement 



of labour the uterus is 

 ^^' • so oblique as to throw 



the fundus far over to 

 the right side, the child 

 presenting by the head 

 and the vertex in the 

 first position, the direc- 

 tion of the expulsive 

 force operating on the 

 infant, will propel its 

 head against the edge 

 or brim of the pelvis, 

 and either cause it to 

 glance upwards into the 

 iliac fossa and let the 

 shoulder come down, or 

 it will be turned over, 

 so as to let the face 

 fall into the opening, and 

 thus produce a face 

 presentation, in which 

 the chin will be direct- 

 ed to the right side, 

 (Fig. 18.) 



and the forehead to the left of the pelvis. 



