AND the self-same _Consequences_ arise from the _Weakness_ and _Tenuity_ of the _MEMBRANES_; when they are so _thin_ and _soft_, that they break, and the WATERS (which are destin’d to lubricate and moisten the _Passages_) flow before their Time: In both which _Cases_, the _Office_ of the WATERS must be supply’d by proper _Fomentations_, and _Oils_, which (however costly) falls far short of the _Effect_ of what is so _Natural_. However, in short, neither of these _Conditions_, under the diligent _Hand_ of the expert MIDWIFE, can differ far from the _Case_ of an _Easy BIRTH_, as already defin’d; wherefore I proceed regularly to—— [Illustration] CHAP. VIII. _Of Difficult BIRTHS, proceeding from the Causes of the PELVIS._ DIFFICULT _BIRTHS_ on part of the _Passages_, happen frequently, because of some perverse _Form_ of the _PELVIS_, in these Respects; as by its being either too _Large_, too _Narrow_, or too _Smooth_. But that I may be the better understood in this Matter: _FIRST_, by a _PELVIS_ too _large_, I mean such an _One_, as is so in comparison with the WOMB or INFANT; in which _Condition_, as the Womb can neither be firmly _fix’d_, compactly _inclos’d_, or duly supported, so neither can the HEAD of the _Infant_ and the _WATERS_ be exactly depressed upon the _Orifice_: Hence it often happens, that (besides the MIDWIFE’S careful _Hand_) the _Privities_ are the best, if not the only _Defence_, against both the WOMB and the CHILD’S falling out of the Body. SECONDLY, By a _PELVIS_ too _small_, I mean, _such_ an _One_ as is so, in Consideration of the SIZE of the whole Body; in which _Condition_, the _INFANT_ commonly answering to that _Proportion_, its _Head_ can by no Possibility pass thro’ the _PELVIS_, in a WOMB well seated, without great _Force_, by which Means the WOMB may be easily turn’d _obliquely_: And thus consequently the _Smallness_ of the _PELVIS_, may sometimes prove the _Cause_ of a _Preternatural_, as well as of a _Difficult BIRTH_; and not only so, but also the _Death_ of both the _MOTHER_ and _CHILD_ may ensue thereupon, unless timely deliver’d by an _Artful Hand_. THIRDLY, By a _PELVIS_ too _smooth_, I mean such an _One_, whose _Distance_ betwixt the _OSSA PUBIS_ and the prominent Part of the _OS SACRUM_ is too _narrow_; in which _Condition_, tho’ the WOMB be well placed, it cannot admit the _Head_ (especially if large and well-grown) without great _Difficulty_: And this _smooth PELVIS_ may also very easily turn the WOMB (either way) _obliquely_, and consequently prove of the same dangerous consequential _Effect_ with the preceeding _Case_.