^" OBSTETRICS. 



various malformations hence result, involving an imperfect discharge 

 of the function. ^ 



^ It will be borne in mind by the student, that there is, in the foetal 

 circulation, a deviation from the normal function in several of the 

 vessels. The umbilical vein and ductus venosus carry arterial 

 blood ; while the umbilical arteries and ductus arteriosus carry 

 venous blood. (Fig. 15.) 



PREMATURE EXPULSION OP THE FtETUS. 



The uterus sometimes expels its contents before the full period of 

 utero-gestation is accomplished. This may occur at any time during 

 gestation, though it appears to be more easily excited at, or previous 

 to, the third month, owing to the frailty of the connexion between 

 the ovum and the decidua. It is also more liable to occur at the 

 commencement of each menstrual return, than in the interval, owing 

 to the increased excitement of the gestative organs at that. time. It 

 is called abortion when the foetus is expelled before it is capable of 

 maintaining an independent existence, that is, before the seventh 

 month. It does sometimes happen that a fcetus lives when expelled 

 before this time, but such cases are rare. The child is hardly con- 

 sidered " viable" before this time. 



Premature labour signifies the expulsion of the ovum before the 

 full term of pregnancy has expired, but after the seventh mofith ; in 

 other words, after the child has become viable. 



Causes. — These are infinitely various and numerous, and include 

 almost every agency capable of acting injuriously on the mother, 

 and through her on the foetus. Mental emotions, fright, anger, joy, 

 or sorrow, when excessive, intense pain, shocks, blows, falls, great 

 fatigue, deficient nourishment, debilitating evacuations, acute and 

 chronic disease, the exanthemata, syphilis, and the habits of life, 

 either extreme, being capable of producing it. To these we may 

 add a peculiar constitutional irritability of some females, by which 

 they abort habitually. 



Premature expulsion is sometimes produced by circumstances 

 which compromise the life of the child. Thus certain pathological 

 conditions of the amnion, chorion or decidua, malformations of the 

 placenta, or erroneous insertion of the cord. Or it may occur from 

 the administration of drugs exhibited for the purpose, or otherwise, 

 such as ergot, savine, &c. 



The manner in which these causes act, is either by destroying the 

 child's life, in which method syncope, syphilis, and mercurial saliva- 

 tion seem to act ; or by causing the womb to contract ; or by par- 

 tial separation of the placenta, causing the effusion of blood between 

 that organ and the womb, and finally its entire separation, thus 

 arresting the nutrition and respiration of the fcstus, and producing 

 its death. 



Symptoms. — The patient who is about to miscarry, generally 



