FERTILITY 145 



Abortion 



The frequency of occurrence of abortion shows a considerable 

 range of variation, but it is often an important factor in deter- 

 mining a low fertility. AVith women the frequency of abortion 

 (including premature birth) as compared with birth at full term 

 varies according to different authorities from one in five to one 

 in ten. (The term abortion or miscarriage is usually applied to 

 cases occurring up to the beginning of the seventh month ; to 

 cases after that time, when the child has become viable, the 

 expression " premature labour "is usually applied.) 



Abortion in women is usually heralded by an excessive hsemor- 

 rhage which is sometimes mistaken for menstruation. If, 

 however, the embryo comes away, the bleeding usually ceases 

 within a shorts time. Not uncommonly, however, some of the 

 embryonic tissues are retained and haemorrhage continues and 

 may become dangerous. Abortions should never be disregarded 

 as incidents of no importance, and professional assistance should 

 always be obtained. 



Abortion occurs also in all the domestic animals and occasions 

 considerable annual loss to breeders. It may assume epidemic 

 proportions, when it is due to a particular bacillus which is usually 

 different for each species. Contagious abortion among cattle 

 is especially common and is brought about by a bacillus affecting 

 the placenta (Bang). 



Apart from contagious abortion, the causes of the phenomenon 

 are very various, and may be psychological, physiological, or 

 pathological. Deliberate abortion (as by certain drugs such 

 as ergot or by mechanical- means) in women is a punishable 

 offence, but nevertheless is sometimes carried out. Involuntary 

 abortion may result from any kind of strain or from fright, both 

 of which are common causes with the domestic animals and 

 sometimes also with women. In the mare abortion is especially 

 apt to occur between the sixth and ninth weeks of pregnancy, 

 since about this time the embryo loses its primitive attachment 

 through the yolk sac before acquiring its more permanent con- 

 nection by means of the chorion. The process of " slipping 

 foal " at this time may be regarded as a reversionary one, since, 

 in the marsupial, the yolk sac is (in most species) the sole organ 

 of foetal nourishment, and release from it marks the act of birth. 

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