In about 270 days after impregnation, labor generally commences. There are certain signs by which the female is able to calculate with tolerable certainty about the time she may expect to be confined. Perhaps the most correct mode of calculating is, 280 * days from the last menstrual period till confinement; another calculation is, from the period of quickening, or the first sensation of fetal life, which is usually perceived about four months and a half after conception. During the last month also the child sinks lower down in the abdomen, and the waist becomes smaller. As the time approaches when a woman expects to be confined she of course sees that every thing necessary for the occasion is prepared, and placed convenient and in order, so that at the time everything may be in readiness, and all confusion avoided. Previous to the setting in of labor she frequently suffers from what are called.