It is evident therefore, that presentations of the Trunk are the most unfavorable known, and labor in them is but rarely spontaneous. Nature can but very seldom effect the delivery of the Fœtus herself, and even when she does it is with the greatest risk, both to it and the mother. The accoucheur should always assist therefore, if he can, because even if nature can complete the delivery it is with such danger. The means of assisting, by turning, will be described in another Chapter.
If the fœtus is not at full term, and of course is under the full size, its expulsion may be left to nature safely, but not otherwise.
SECTION V.
THE PHYSIOLOGY OF SPONTANEOUS DELIVERY, OR CHILDBIRTH, AND THE MANNER OF CONDUCTING A NATURAL LABOR.
Having now completed the description of the Mechanism of Delivery, in all the various presentations and positions, it is necessary to explain the physiological phenomena attending a natural labor, and the duties of the accoucheur when conducting it, and to show what assistance he can render, and when he should or should not interfere.