The initial symptoms of pregnancy are so widely known that in most instances the prospective mother herself makes the diagnosis shortly after conception has taken place; but now and then pregnancy advances for several months unrecognized and is then detected by a physician who has been consulted on account of symptoms which the patient has incorrectly attributed to some other condition. On the other hand, women sometimes suspect that they are pregnant when they are not; and such mistakes occur because certain symptoms which are implicitly trusted by the laity as manifestations of pregnancy are occasionally associated with conditions quite foreign to it. It is clear that one interested in the matter must know not only what the manifestations of pregnancy are and when they appear, but also how far the evidence that they give is reliable. The signs of pregnancy may be classified, according to their reliability, as presumptive, probable, and positive. The doubtful evidence appears first and the infallible proof last. No one need be surprised, therefore, if, when her suspicion is first aroused, she is unable to decide positively whether she is pregnant. Physicians of broad experience, possessed of facilities for observation which their patients cannot employ, may find it necessary to make more than one examination before they commit themselves to a definite opinion; in some cases, though very rarely, they must wait for two or three months to be able to do this. THE POSITIVE SIGNS.--The earliest absolutely trustworthy manifestation of pregnancy is the motion of the fetus. The perception by the mother of these movements, which is spoken of as "quickening," generally occurs toward the eighteenth week, if she has been told to watch for them; otherwise they may pass unnoticed until the twentieth week or later. At first the motion, felt in the lower part of the abdomen, is very gentle; it has been variously likened to tapping, or to quivering, or to the fluttering of a bird's wings. As time goes on the movements grow stronger and occur more frequently; they are, however, perceived but rarely throughout the day and seldom interfere with sleep. Occasionally women are annoyed by the sensation and complain that the child is hardly ever quiet. Even these troublesome movements are never a cause for anxiety; but prolonged failure to feel motion after it is once well established should be reported to the doctor.