STAGES OF LABOUR.

Parturition may be divided into two great orders, Eutocia and Dystocia, the one signifying natural labour which follows a favourable course both for the mother and her child; the other signifying faulty or irregular labour, the course of which is unfavourable.

We may define eutocia to be the safe expulsion of the mature foetus and its secundines by the natural powers destined for that purpose. No function exhibits such infinite varieties, within the limits of health and safety to the mother and her offspring, as that of parturition; no two labours, even in the same individual are exactly alike; still, however, the great objects of the process will be the same, viz. 1st. the preparation of the passages and the foetus for its expulsion; 2dly, the expulsion of the foetus; and 3dly, the expulsion of the placenta and membranes.

That we may form a clearer and more comprehensive view of this process, labour has usually been divided into stages or periods, marked by the changes just now alluded to: hence it is generally said to consist of three stages; the first, or preparatory stage, commencing with the first perceptible contractions of the uterus, and terminating in the full dilatation of the os uteri; the second, or stage of expulsion, terminating with the birth of the child; and the third, consisting of the expulsion of the placenta.

Preparatory stage.—Precursory symptoms. For some time before the commencement of actual labour, a variety of changes are taking place which must be looked upon as the precursors of this process: during the last weeks of pregnancy, nature appears, as it were, to be preparing for the great change which is at hand, and to be making such arrangements as shall enable it to be completed with the least possible danger both for the mother and her child.

One of the earliest warnings which we have of approaching labour is an alteration in the form of the abdominal tumour; the cervix uteri has by this time (especially in primiparÆ) entirely disappeared; the presenting part of the child has therefore descended to the lowest part of the uterus; the fundus has sunk lower and more forwards; and from the diaphragm being enabled to act with greater freedom, the respiration is performed with more ease and comfort to the patient; she therefore feels more capable of moving about, and is in better health and spirits than for some time previously. Upon examination per vaginam, the head will be found deep in the cavity of the pelvis, covered by the lower and anterior segment of the uterus; the os uteri is still closed, and situated in the upper part of the hollow of the sacrum, forming merely a small circular depression. In women who have already had children, a portion of the cervix uteri is still remaining; it is thick and bulky; and in some cases, where the uterus has been greatly distended in several successive pregnancies, it is nearly as long as in the unimpregnated state; the os tincÆ or os uteri externum is open, its edge irregular from former labours; the upper extremity of the canal of the cervix is contracted, and forms the os uteri internum; it has been closed during the greater part of pregnancy, but usually is now sufficiently open to admit the finger; the os uteri is neither so high up nor so far backwards in the pelvis as in primiparÆ, and is reached with greater ease; whereas, the head of the child, instead of being felt in the cavity of the pelvis, generally remains at the brim until labour is more advanced.

First contractions. The first contractions of the uterus (in a state of health) are so slight as scarcely to be noticed by the patient: they create a sensation of equable pressure and general tightness round the abdomen, and during the contraction the uterus feels somewhat firmer, but they are neither attended with pain, nor do they appear at first to have any effect upon the os uteri; these precursory contractions generally come on a day or two before actual labour commences, and sometimes are felt at intervals for one or two weeks. Where the uterus has been exposed to any source of irritation, and especially where there is a disposition to rheumatic affection of this organ, they may produce much suffering and give rise to one form of what are called false pains, hereafter to be described. “The first contractions, says M. Leroux (Sur les Pertes de Sang, § 41.,) are feeble, and communicate no sensation to the patient; in order to discover them we must hold our hand upon the abdomen, and if we feel the globe of the uterus raise itself and become hard, this is a true contraction. These contractions gradually increase until they excite pain: but pain is not essential to a contraction; it depends on the distension and compression of the nerves produced by the resistance of the body upon which the uterus acts, and increases in severity in proportion to the degree of resistance and contraction.”

In proportion as the lower part of the uterus descends into the cavity of the pelvis, so does it exert a degree of pressure on the neighbouring parts; the capacity of the bladder and rectum is diminished; and being therefore unable to contain the usual quantity of urine and fÆces, and being probably rendered more irritable by the pressure above-mentioned, the patient experiences frequent calls to pass water and evacuate the bowels, which is sometimes effected with considerable difficulty: in some instances she is obliged to lean forward, or support the abdomen, in order to take the weight of the child off the neck of the bladder before she can empty it: the same cause occasionally requires the use of the catheter, and sometimes renders the introduction of it a matter of considerable difficulty.

As these various changes make their appearance, the patient becomes restless and anxious; she cannot remain long in the same posture; the slight precursory contractions which have been just described, are becoming stronger, and begin to produce a sensation of pain; the os uteri (in primiparÆ) opens somewhat, its edge at first is exceedingly thin, and feels almost membranous; by degrees however it swells, grows thick and cushiony, and is now more dilatable.

Action of the pains. The os uteri does not dilate merely by the mechanical stretching which the pressure of the membranes and presenting part exert upon it; it dilates in consequence of its circular fibres being no longer able to maintain that state of contraction which they had preserved during pregnancy; they are overpowered by the longitudinal fibres of the uterus, which, by their contractions, pull open the os uteri equally in every direction.

The vagina also swells and grows more cushiony, and this is followed by a copious secretion of colourless and nearly inodorous mucus. “The more albuminous it is the better, and it is always a good sign when lumps of albuminous matter come away from time to time; the thicker, softer, and more cushiony the os uteri is, the more mucus does it secrete.” (Wigand, Geburt des Menschen, vol. ii. p. 292.) The thin hard os uteri does not dilate, its fibres are all in close contact, and like a well-twisted cord will not yield; whereas, when they are separated from each other by the swelling of the os uteri, they easily yield to the dilating force which is applied to them. Besides serving the purpose of lubricating the passage, the secretion of mucus is of great importance as a topical depletion, for, by thus unloading the congested vessels, they diminish the vascularity and heat of the part, and render it more capable of dilatation. “If, on the other hand, the entrance of the vagina is small, the neighbouring parts cool, dry, inelastic, and as if tightly stretched over the bones; if the finger, in spite of being well oiled and carefully introduced, produces pain upon the gentlest attempt to examine, we may expect a tedious and difficult labour.” (Op. cit. p. 190.)

The patient is now no longer able to conceal her pains when they come on. If she be in the act of conversing she stops short, and remains silent until the severity of the pain is over; if she be walking about her room she is obliged to stand still for the time, and rest against or hold by something until the pain has gone off. The true labour pains are situated in the back and loins; they come on at regular intervals, rise gradually up to a certain pitch of intensity, and abate as gradually; it is a dull, heavy, deep sort of pain, producing occasionally a low moan from the patient: not sharp or twinging, which would elicit a very different expression of suffering from her.

Auscultation during the pains. “If we direct our attention to the changes of tone which the uterine pulsations present during auscultation, we shall find them generally stronger, more distinct and varied in tone during labour; and this is especially the case just before a pain comes on. Even if the patient wished to conceal her pains, this phenomenon, and more especially the rapidity of the beats, would enable us to ascertain the truth. The moment a pain begins, and even before the patient herself is aware of it, we hear a sudden short rushing sound, which appears to proceed from the liquor amnii, and to be partly produced by the movement of the child, which seems to anticipate the coming on of the contraction: nearly at the same moment all the tones of the uterine pulsations become stronger; other tones, which have not been heard before, and which are of a piping resonant character, now become audible, and seem to vibrate through the stethoscope, like the sound of a string which has been struck and drawn tighter while in the act of vibrating. The whole tone of the uterine circulation rises in point of pitch. Shortly after this, viz. as the pain becomes stronger and more general, the uterine sound seems as it were to become more and more distant, until at length it becomes very dull, or altogether inaudible. But as soon as the pain has reached its height and gradually declines, the sound is again heard as full as at the beginning of the pain, and resumes its former tone, which in the intervals between the pains is as it was during pregnancy, except somewhat louder. This is the course of things if the pain be a true one, and attain its full intensity: where the pains are false or irregular it is very different; the uterine sound either remains unaltered, or increases only for an instant, or its seeming increase of distance, as above mentioned, is not observed.” (Die GeburtshÜlfliche Exploration, von Dr. A. T. Hohl, erster theil, s. 105.)

Effect of the pains upon the pulse. It is curious to observe the effect which a regular pain has upon the rapidity of the mother’s pulse; as the former comes on and goes off, so does the other increase or diminish. “The increasing rapidity of the pulse announces the commencement of the pain; it rises and attains its summum with it; and as the pain subsides so does the pulse gradually resume the rate which it had during the intervals; a similar ebb and flow may be heard in the uterine souffle. The more regular the pain is, and the more distinctly it rises to its full extent, the more marked, regular, and distinct, is this change in it. We may also invert the order of things, and say, the more distinctly the rapidity of the pulse comes on and announces the pain, the more regularly it rises and attains a certain height, which it maintains, and then gradually subsides; in like proportion will the pain be more perfect, attain its full extent more completely, and act more efficaciously upon the regular progress of the labour. Where however the rapidity of the beats subsides before it had scarcely begun to increase, the pain is too weak; or where the rapidity rises by sudden starts, the pain is a hurried one; and in either case its effect will be imperfect.” (Hohl, op. cit. vol. i. p. 108.) In order that we may ascertain these changes correctly, we ought to note the rapidity of the pulse during each successive quarter of a minute as directed by M. Hohl; thus, in a pain which lasts two minutes, the increase and diminution in the rapidity of the pulse may be as follows, 18. 18. 20. 22.; 24. 24. 22. 18. As labour advances it increases, so that shortly before the birth of the child we shall find that what was the rate of the pulse during the height of the pains at the beginning is now the rate of it during the intervals.

Symptoms to be observed during and between the pains. When a pain comes on, the uterus grows hard and tense; if the fundus be somewhat to one side, as is not unfrequently the case, it now gradually moves, so that the median line of the uterus corresponds with that of the patient’s body; the various prominences of the child are no longer to be felt, the whole is now firm and unyielding; the os uteri is put tightly upon the stretch, the membranes which were loose become tense and are firmly pressed against it, and the presenting part is rendered indistinct: as the pain gradually subsides, the uterus becomes softer, and yields to the pressure of the hand; the different parts of the child which project, as also its movements, can now be felt more distinctly; the patient is free from pain, and feels herself in an agreeable state of tranquillity, which is frequently attended by a short refreshing doze; the os uteri, which has become somewhat more dilated during the last pain, is now soft and loose, so that we can hook the finger into it and move it about; the tight bladder of membranes becomes relaxed and flaccid, and retracts more or less into the uterus, so that we shall now be able to introduce the finger into the os uteri and feel the presenting part through the membranes; while the presenting part of the child, which during the pain was fixed, can be moved somewhat by the finger.

Characters of a true pain. In examining the course of a true pain we shall find that the contractions of the uterus do not begin in the fundus, but in the os uteri, and pass from the one to the other. (Wigand, op. cit. vol. ii. p. 197.) Every pain which commences in the fundus is abnormal, and either arises from some derangement in the uterine action, or is sympathetic with some irritation not immediately connected with the uterus, as from colic, constipation, &c. We very seldom find that a contraction of the uterus, which has commenced in the fundus, passes into the cervix and os uteri, and becomes a genuine effective pain; usually speaking, the contraction is confined to the circumference of the fundus, without detruding the foetus at all. When a genuine pain comes on, so far from the head being pressed against the os uteri, it at first rises upwards, and sometimes gets even out of reach of the finger, whilst the os uteri itself is filled with the bladder of membranes: if it had commenced in the fundus instead of the inferior segment of the uterus, so far from the head being drawn up at the first coming on of the pain, it would have been forcibly pushed down against the os uteri. In the course of a few seconds the contraction gradually spreads over the whole uterus, and is felt especially in the fundus; the head which had been raised somewhat from the os uteri is now again pushed downwards to it, and seems to act as a wedge for the purpose of dilating it; it is not until the whole uterus is beginning to contract that the patient has a sensation of pain. We may, therefore, consider that a genuine uterine contraction consists of certain phenomena which occur in the following order: first, the os uteri grows tight, and the presenting part rises somewhat from it; then the rest of the uterus, especially the fundus, becoming hard, the patient has a sensation of pain, and the presenting part of the child advances. The period of time necessary for all these changes varies not only in different individuals, but in the same individual in different labours, and in different stages of the same labour.

“The more completely the os uteri is opposite the fundus, and the more the axis of the uterus corresponds with that of the pelvis, the sooner are the pains, cÆteris paribus, capable of dilating the os uteri.” (Wigand, vol. ii. p. 273.) The cushiony state of the vagina and os uteri, and the free secretion of thick albuminous mucus from these parts, as already mentioned, will be of great importance in ensuring their easy dilatation. Where this secretion is either absent, or very scanty, the passages become dry, hot, and tender, from no relief being afforded to the congested vessels by its effusion; and vice versÂ, where there is a febrile state of the circulation and considerable topical excitement, the secretion is sparing, or, perhaps, stops entirely. This state may arise from a variety of causes, such as from general plethora, too warm clothing, bad ventilation, derangement and irritation of the primÆ viÆ, and abuse of spirituous and other stimulating liquors: it may arise from constipation, or may be induced by rough and too frequent examination. The patient becomes flushed, excited, and feverish, with a hot skin, dry tongue, thirst, and headach; the uterine contractions become irregular, they produce much suffering, and but very little advance in the progress of the labour; the passages are in a state of inflammation, and more especially the os uteri, which is much swollen and excessively tender. The process of labour is completely interrupted, and can only be restored to a healthy condition by bleeding, warm bath, laxatives, and enemata.

Formation of the bag of the liquor amnii. When the os uteri has dilated more or less, a quantity of liquor amnii begins to collect between the head and the membranes, so that when a pain comes on they form a tense, elastic, and conical bag, which presses firmly against the os uteri, and protrudes through it into the vagina, and from its form and elastic nature greatly facilitates the speedy dilatation of it. If the edge of the os uteri be still thin, it will become so tense during the pain, and the bag of membranes will press so firmly against it, that we shall have some difficulty for the moment in distinguishing the one from the other. As the labour advances, the intervals between the pains become shorter, whereas the pains themselves are of longer duration and more effective. In this way pain succeeds pain until the os uteri, at length, attains its full degree of dilatation; if the membranes have not yet ruptured, we may now expect them to burst with every succeeding pain.

Rigour at the end of the first stage. At this moment the patient is occasionally seized with a sudden and violent fit of shivering, so much so as to make the teeth chatter, and even communicate a tremulous motion to the bed itself; this is not the result of cold, nor is it relieved by the application of external warmth; and, in many cases, the patient will express her surprise that she should shiver thus violently, and yet not feel cold. It appears to be a modification of convulsive action, excited by sympathy between the os uteri on its becoming fully dilated, and certain muscles in other parts of the body.

Show. On examination at this stage of the process, streaks of blood will be found in the mucus which soils the finger, and sometimes it amounts to a slight discharge of blood: this appearance is called by midwives “a show,” as it usually indicates that the os uteri is nearly or fully dilated. It is produced by a separation of the membranes from the vicinity of the os uteri, and consequent rupture of any little vascular twigs which may have passed from the uterus to them.

The full dilatation of the os uteri terminates the first stage of labour. During this stage, the action of the pains does not appear to have been so much for the expulsion of the child, as for preparing it as well as the passages for this purpose, viz. by so arranging and regulating the different forces of the uterus, and at the same time by giving the child such a position (i. e. with its long axis parallel to that of the uterus,) and the os uteri such a degree of dilatation, as shall ensure its expulsion with the greatest possible ease and safety.

Duration of the first stage. The duration of the first stage of labour varies exceedingly, both in primiparÆ and those who have had several children; nor is it at all easy to determine with precision the exact moment when labour commences. The sensation of pain to the patient is no guide whatever, for what is attended with much suffering in one patient is scarcely sufficient to excite the notice of another. The dilatation of the os uteri as marking its commencement, must also be taken with some caution: in primiparÆ, where it generally remains closed until the contractions are becoming painful, it would obviously be wrong to date the commencement of labour from the moment that the os uteri opens, as regular uterine contractions have been evidently present for some hours previously, although not of sufficient force to produce actual pain. On the other hand, in women who have already had several children, the os uteri is found open some days and even weeks before labour comes on. As a general rule, we may state that regular and genuine contractions of the uterus, sufficiently powerful to produce pain, seldom require more than six hours to effect the full dilatation of the os uteri; in many cases a much shorter time will be sufficient; whereas, in others, the first stage of labour may last for more than quadruple this period before it is completed: in neither can it be considered as abnormal; and we usually find that where the pains of the first stage have been slow and lingering, they become remarkably quick and active during the second stage. This agrees with the experience of Dr. Churchill, in his report of the Western Lying-in Hospital at Dublin, viz. that, “no evil consequences resulted, and they (the labours where the first stage was so protracted) were amongst those in whom the remaining stages of labour were shortest.”

The first stage terminates with the full dilatation of the os uteri; the rupture of the membranes is a change which is necessarily more or less uncertain, as to the precise period of labour at which it takes place. Thus, in primiparÆ, it frequently occurs before the first stage is completed; whereas in other cases the membranes sometimes do not give way until the head approaches or has even passed through the os externum; generally speaking, however, they burst at this period of the labour, and usually effect a remarkable change in the whole process. The pains are now of longer duration and more powerful, the intervals between them are shorter, and yet, although the suffering is actually more severe, it is more tolerable to the patient than that of the first stage. During the first stage they are chiefly confined to one spot in the loins; and as they must necessarily continue for some hours without any distinct evidence of the labour being advanced by them, the patient feels discouraged and gets a little impatient at the endurance of so much apparently useless suffering: but as soon as the gush of liquor amnii takes place, she feels that a great alteration has been produced; the abdomen becomes smaller: the pains assume a very different character, and every thing combines to assure her that she has made progress, and encourages her to patience and resolution.

Description of second stage. The os uteri has now disappeared entirely, so that the vagina and uterus form one continuous canal, and is thus admirably adapted for the easy passage of the head: the anterior lip, however, dilates much more slowly than the other parts of it, and this is especially the case in primiparÆ, for, being pressed between the head and pelvis it becomes oedematous, and swells to a considerable size: if the pains be strong, it is pushed down more or less before the head, and may be frequently felt beneath the symphysis pubis, and occasionally it is detruded so far as to be visible between the labia. According to Wigand, the swelling of the anterior lip sometimes attains such a size as makes it liable to be mistaken for the bladder of the membranes (op. cit. vol. ii. p. 308;) it seldom produces much obstacle to the advance of the head, and with a little patience gradually disappears of itself. All attempts to push it up above the head are objectionable, because, in the first place, the finger cannot reach sufficiently high to effect this object, and therefore the swelling descends again to its former situation; and, secondly, the efforts to push it up only tend to inflame it and increase the swelling. Those who imagine that they can push up the anterior lip of the os uteri above the head deceive themselves; and even if they do succeed, it merely shows that had they let it alone, it would have gone up very shortly of itself.Straining pains. As the head enters the vagina, not only do the contractions of the uterus become much more powerful, but now another set of forces are called into action, and the half involuntary efforts of the abdominal and other muscles come to aid the uterus in expelling its contents. The sole object of this stage is the expulsion of the child, and even the vagina by its contractions contributes to effect it. The head is therefore subjected to considerable pressure; hence we may now feel the cranial bones overlapping each other at the sutures, and the fontanelles diminished in size; and, from the tightness with which the head is embraced by the vagina, the circulation in the scalp is more or less impeded, and a large oedematous swelling, called caput succedaneum, forms on that part of the head which presents.

Each pain is attended with a violent and irresistible impulse to bear down, and every muscle which can assist in effecting this object is now brought into play. The tone of the patient’s voice, the expression of her face, the hurried breathing and sudden inspiration, stopping short the moment a pain comes on, in order that she may add still greater power to the efforts which she is about to make, all betoken a very different process to that of the first stage, and one which requires a powerful struggle of muscular strength and energy for its completion. Hence it is that the sound of the patient’s voice during the pain is frequently of itself sufficient to inform us how far labour is advanced, for “we never see the really powerful straining pains come on (the head may be never so low in the pelvis,) so long as the os uteri is not fully dilated.” (Wigand, op. cit. vol. ii. p. 310.) This is a wise provision of Nature, for by this means it prevents the danger of laceration to which the os uteri would be otherwise exposed, and shows the importance of not permitting a patient to strain and bear down until the os uteri be fully dilated. In those cases where a patient has been induced to exert herself prematurely, the efforts being voluntary are never so powerful, and soon produce much fatigue.

Several reasons have been assigned why the straining pains should come on at this stage. It cannot be owing to the pressure of the head upon the parts of the pelvis, as has been supposed and especially the rectum, thus producing the sensation of a violent desire to evacuate the bowels, because, in almost every case of first labour, the head for several days before the actual commencement of labour is sufficiently deep in the pelvis to produce these effects. It evidently arises from a sympathetic connexion “between the os uteri and vagina on the one hand, and the abdominal and other muscles on the other. We see this connexion most distinctly in those difficult labours where the head is pushed down deeply in the pelvis even to the very outlet, and where the os uteri which is but little dilated is protruded before it. In such cases we never see the really powerful and continued action of the abdominal muscles excited, let the head press never so forcibly upon the rectum; but as soon as the os uteri (perhaps after much suffering) has retracted over the head, the whole auxiliary action of the abdominal muscles commences.” (Ibid. vol. ii. p. 467.)

There is the same relation between these muscles and the vagina, as there is between them and the rectum: the moment the vagina becomes distended, it begins to contract upon the distending body, and like the rectum excites them to strong and involuntary action. The tenesmus of dysentery is a sympathetic action of the same nature; the rectum is highly irritated by the acrid nature of its contents, and excites an irresistible disposition to bear down. The patient wishes for the next pain and yet she dreads it, from the suffering it creates, and the tremendous effort which it compels her to make; the pulse is quicker, and is not only so during the intervals, but undergoes a greater increase of rapidity during the pains themselves than in the first stage; the face becomes red, swollen, and bathed in perspiration; the breath is hurried; the lips are apart; the eyes are wild; every thing betokens a state of the highest excitement. When a pain comes on, she catches hold of whatever she can reach, plants her feet upon any thing which is firm, and, by thus fixing her extremities, she is enabled to bear down with greater power and effect. During the struggle the face often changes its expression surprisingly, so much so, that even her own attendants would scarcely recognise her.

Dilatation of the perineum. As pain succeeds pain, gradually increasing both in force as well as duration, the head descends along the vagina, and begins to press against the perineum; the rectum becomes flattened; the sphincter ani dilated, and therefore any fÆcal matter which may have been lodging there is unavoidably expelled; the anterior wall of the rectum is pressed close against the anus, and where the pressure is very great, even protrudes somewhat through it; the hÆmorrhoidal veins are frequently much distended, and form a roll of cushiony swelling around the anus. A small quantity of liquor amnii dribbles away from time to time, but is neither during a pain, nor during the absence of a pain, for in the former case the pressure of the head acts as a plug and prevents its escape, and in the latter there is no uterine contraction present to expel it: the liquor amnii dribbles away only at the moment when a pain is coming on or going off.

Expulsion of the child. As the head descends farther it begins to press more powerfully on the perineum, and during each pain pushes it out like a large ball; and then, as a contraction goes off, and the resiliency of the soft parts regain their superiority, it retires again. The breadth of the perineum (viz. from the anus to the vulva) increases, whilst it diminishes considerably in thickness, especially towards its anterior margin. Whilst passing through the inferior aperture or outlet of the pelvis, the head advances more or less forwards under the pubic arch, and begins to distend the os externum; during a pain it separates the labia, and protrudes between them, and again retires as the pain goes off; a larger and larger portion of the head gradually forces itself through the os externum as this dilates; the perineum becomes still thinner, so that at length it is scarcely thicker than parchment. When more of the head has passed through, it does not now recede when the pain goes off; the os externum and perineum are at their greatest distension, for the largest diameter of the head, which is presented to the os externum is now encircled by it; the next pain brings the head into the world.

This is the moment of greatest pain, and the patient is frequently quite wild and frantic with suffering; it approaches to a species of insanity, and shows itself in the most quiet and gentle dispositions. The laws in Germany have made great allowances for any act of violence committed during these moments of phrenzy, and wisely and mercifully consider that the patient at the time was labouring under a species of temporary insanity. Even the act of child-murder, when satisfactorily proved to have taken place at this moment, is treated with considerable leniency. This state of mind is sometimes manifested in a slighter degree by actions and words so contrary to the general habit and nature of the patient, as to prove that she could not have been under the proper control of her reason at the moment. It is a question how far this state of mind may arise from intense suffering, or how far the circulation of the brain may be affected by the pressure which is exerted upon the abdominal viscera.

A short cessation of pain succeeds the birth of the head. The violent distension of the os externum has ceased for a time, and the patient feels comparatively easy; but in the course of a few minutes the pains return as before, although not quite so severe: first, the shoulder, which is turned forwards, passes under the pubic arch, followed by the other which sweeps over the perineum. The rest of the child is expelled with comparative ease, and as soon as its pelvis has passed through the os externum, a gush of the remaining liquor amnii, which had been retained in the upper portions of the uterus, follows; the whole abdomen instantly sinks and becomes flaccid, while the uterus contracts into a firm globe upon the placenta, which is shortly to be expelled. A most delightful and perfect calm succeeds, and the sense of freedom from suffering, and joy for the termination of her trial, are expressed in the liveliest terms of gratitude.

Third stage.—Expulsion of the placenta. The period between the birth of the child and expulsion of the placenta varies considerably. Sometimes it follows the child very rapidly, so that, apparently, they are both expelled by the same effort of uterine action; at others, the interval is more considerable. There is generally an interval of ten or fifteen minutes, and then pains of a totally different character make their appearance: these are supposed to denote the separation of the placenta from the uterus, and, from their being usually attended with discharge of more or less blood, have been termed dolores cruenti by many of the foreign writers. The expulsion of the placenta is attended with little or no suffering; it descends into the vagina inverted, i. e. with its foetal or amniotic surface turned outwards: whether or not this is produced by pulling at the cord is perhaps a question.

Twins. If there be twins, the placenta of the first child is seldom expelled until after the birth of the second child. The membranes of the second ovum become distended with liquor amnii, project into the vagina and burst as in a common single labour; the passages have been sufficiently dilated and prepared by the birth of the first child, so that, when the uterus begins to contract, the expulsion of the second will be readily and easily effected. The uterus may resume its efforts for this purpose in twenty minutes after the birth of the first child, or it may remain quiescent for several hours without at all disturbing the regular and natural course of the process which will be precisely the same as in the previous case.

The placentÆ of twins are usually expelled together, forming one large placentary mass; their vessels, however, are distinct from each other, so that with care one placenta can be peeled away from the other. In other cases, they are separated from each other by an intervening space of membranes; and in one rare instance of triplet placentÆ the umbilical arteries of two placentÆ anastomosed with each other, before dividing into smaller branches.

Upon the expulsion of the placenta, the uterus, being now emptied of its contents, contracts into a firm hard ball, which may be felt behind the symphysis pubes, or sometimes a little to one side, of about the size of a full grown foetal head. This state of hard contraction gradually disappears, and a discharge of blood called lochia follows, which having continued for a few days becomes colourless, and at length ceases altogether. For a description of the changes which the uterus and passages undergo in returning to their former condition as in the unimpregnated state, we refer to the chapter on the Female Organs of Generation.