The duration of natural labor is not by any means constantly the same, nor can it be predicted with anything like certainty in any case; but still by keeping careful records, and by duly observing a vast number of cases, a tolerable approximation can be made. There are various circumstances that tend to lengthen the duration of labor, some general, and others belonging to the individual. The mode of life and early habits of the female, the climate in which she lives, and the manner in which she has conducted herself during gestation, all have an important influence. As a general rule, the period becomes longer in proportion to the civilization of the community in which she lives. The first labor is generally more tedious than the succeeding ones, owing to the slower dilatation of the parts. It is also thought by some, that the labor is longer in proportion to the age of the female, particularly with the first child; but this opinion is not well founded. The average duration of labor in our country, is _from eight to twelve hours_. In some parts it is longer than this, and in others again it is much shorter. I have good reason also to think, that it is longer in cities than in the country. An experienced practitioner can sometimes predict with tolerable certainty, when called to a labor, how long it will be before it is over; but this is seldom the case, and most frequently his success is owing more to chance than to judgment. If the mouth of the womb be well dilated, the contractions powerful, and the patient vigorous, with the presentation natural, he is of course justified in predicting a speedy delivery; or the reverse, if these favorable conditions do not exist. Many unforeseen conditions may exist, however, and many accidents arise, that may falsify an apparently safe conclusion. No judicious practitioner, except in a few rare cases, will hazard his reputation by fixing any _time_, and no well informed patient would _ask_ him to do so, because she would know that it was out of his power. CHAPTER XVII. THE CONDUCT OR MANAGEMENT OF A NATURAL LABOR. PRELIMINARY REQUISITES.