There are other circumstances also connected with the catamenia, which warn us against placing too much confidence in its disappearance as a sign of pregnancy: a woman may become pregnant who has never menstruated, a fact which has been noticed by several authors, and which has been explained as well as confirmed by Levret in his _Art des Accouchemens_, § 230:--"A woman," says he, "may conceive, although she has not yet menstruated, provided menstruation would otherwise have made its appearance shortly."[35] Another circumstance, of much more frequent occurrence, is the fact that a woman may become pregnant without having had a return of the menses since her last confinement; hence we occasionally meet with cases where, from a rapid succession of pregnancies, the menstruation has not appeared for several years. From what has now been said, it will be seen, beyond all doubt, that the non-appearance of the menses cannot be looked upon by itself as a diagnostic of pregnancy, or _vice versâ_: this is more particularly the case when any morbid condition of the system is also present; under such circumstances, little or no confidence can be placed upon it as a guide in forming our diagnosis. In cases where it is an object to conceal pregnancy, the appearance of the menstrual fluid upon the clothes has been imitated in order to deceive. (Montgomery, _op. cit._ p. 50.) Although, therefore, the cessation of the menses, when taken in connexion with other symptoms, will prove useful in assisting us to a correct opinion, nevertheless, when taken by itself, it will scarcely ever enable us to decide with certainty.