903 



PARTURITION. 



diameter to the other was first pointed out by 

 Professor Naegele, of Heidelberg, and must 

 be looked upon as a fact of great importance in 

 the mechanism of parturition, second only to 

 the discovery of the oblique position of the 

 head by Solayres de Renhac and Matthias 

 Saxtorph in 1771. Sometimes the head does 

 not make the change above mentioned, but 

 comes out with the forehead more or less for- 

 wards, the swelling of the cranial integuments 

 being situated on the right or left frontal bone. 



The face, like the head, may present in two 

 ways, either with the right or the left side fore- 

 most. As in the head presentations the sagittal 

 suture crosses the os uteri, so in the present 

 instance is this the case with the ridge of the 

 nose. 



In that position which is of most frequent 

 occurrence the chin is turned to the right side 

 of the pelvis, the right eye and zygoma being 

 lowest and in the middle of the pelvis ; this, 

 therefore, shows that the face, like the head, 

 comes obliquely not only as to the transverse 

 diameter of the pelvis, but also as to the axis 

 of its brim. The ridge of the nose is not only 

 the part of the face which we first are able to 

 distinguish when the os uteri is but slightly di- 

 lated, but from its conducting the finger in one 

 direction to the soft cushiony end of the nose, 

 and in the other to the broad hard expanse of 

 the forehead, it furnishes us with an excellent 

 means of ascertaining not only that the face 

 presents, but in what position. 



As the os uteri dilates and the face advances, 

 the chin turns towards the right foramen ovale, 

 so that by the time it has entered the vagina, it 

 is no longer the right eye and zygoma which 

 form the presenting part, but the right cheek, 

 this being now the part which the finger first 

 touches upon during examination, precisely as 

 in the first position of the head, it is the su- 

 perior and posterior quarter of the right parietal 

 bone ; so, in like manner, it is this part of the 

 face upon which the bruise-like swelling is 

 situated, which it brings with it into the world. 

 It would seem that there is a considerable ana- 

 logy between the first position of the head and 

 that of the face, and that the one can probably 

 pass into the other; in both the right side pre- 

 sents, and if the head in this position swings 

 round upon its transverse diameter, it becomes 

 the first position of the face. 



The other or second position of the face is 

 merely the reverse of the first. The left eye 

 and zygoma present at the beginning of labour ; 

 and as the chin, which is turned more or less 

 to the left, moves somewhat forwards, it be- 

 comes the left cheek which first passes through 

 the os externum, and upon which the swelling 

 of the face is situated. 



According to the best averages, we may state 

 that face presentations occur about once in 290 

 labours, and from the observations of Professor 

 Naegele, jun., the proportion of the second po- 

 sition to the first is as 1.29 to 1. Beyond 

 being now and then a little more tedious, la- 

 bours where the face presents are not more un- 

 favourable for the mother than where the head 

 presents ; for the child, however, they are not 



so favourable; the pressure upon the neck pro- 

 duces considerable cerebral engorgement, which 

 now and then proves fatal. 



The lower part or pelvic extremity of the 

 trunk may present with the nates, the knees, or 

 the feet ; but as the former are by far the most 

 bulky, we mav bring them under the general 

 head of nates presentations. In this case the 

 child may present with the back or abdomen 

 forwards, in either of which the transverse dia- 

 meter of its pelvis runs obliquely, that ischium, 

 which is turned forwards, being lowest in the 

 pelvis. The position with the back of the child 

 more or less forwards is the most common, 

 being in the proportion of 3 to 1 of the other 

 position. The presenting ischium advances 

 through the os externum ; the abdomen and 

 chest follow ; and the arms, which are crossed 

 upon the breast, are usually born at the same 

 moment. The shoulders follow in the same 

 direction, that shoulder being first expelled 

 which is turned more or less forwards. The 

 head, with the chin pressed upon the breast, 

 enters the pelvis in the opposite oblique dia- 

 meter to what the shoulders did ; and while 

 the occiput rests against the symphysis pubis, 

 the chin, followed by the rest of the face and 

 forehead, sweep over the perineum as the head 

 turns upon its transverse diameter from below 

 upwards. Sometimes, although rarely, the 

 chin is not depressed upon the breast, but the 

 head enters the pelvis in a contrary direction, 

 viz. with the occiput pressed into the nape of 

 the neck, the face turned upwards, and is born 

 in this position. Where the abdomen of the 

 child is turned forwards, it almost invariably 

 turns more or less backwards during the pro- 

 gress of the labour, either shortly after the 

 nates are expelled, or as the thorax is advancing 

 through the pelvic outlet. 



In all these presentations, the process of la- 

 bour appears to resemble, as far as possible, 

 that in the lower classes of animals. The first 

 stage is employed in attaining two important 

 objects ; firstly, in giving the child a natural 

 position, viz. with its long axis parallel with 

 that of the passage through which it has to come, 

 and in so dilating the os uteri that the whole of 

 it shall disappear, the uterus and vagina forming 

 one continuous canal, exactly resembling-, as far 

 as the mechanism of the expulsion is concerned, 

 the same process in the lower animals. 



As far as we know, it is only in the human 

 subject where it is possible for the foetus to 

 present across, or where its long axis does not 

 correspond witli that of the passage ; in this case 

 it presents with the arm or shoulder, and can- 

 not be born in this position. This unnatural 

 presentation chiefly arises from the contractions 

 of the uterus in the first stage being more or less 

 perverted or obstructed by certain causes; thus 

 if the uterus be much distended with liquor 

 amnii, the slight precursory contractions at the 

 commencement of labour will have little or no 

 effect in keeping the foetus with its long axis 

 parallel with that of the uterus, for the sides of 

 the uterus are now too far separated to act upon 

 it, and as the uterus from its distention ap- 

 proaches to the globular form, the child will lie 





