Obstetrics (Lat. obstetrix, a midwife), the art and science of midwifery. It has a double mission: 1, to render possible, easy, and regular, exempt from all abnormal suffering and all danger, the accomplishment of the numerous functions which directly or indirectly affect generation, from birth to the age when the procreative faculty becomes natural to the human female; 2, to direct and defend from all harm the delicate and precarious health of the infant during its early period of existence, and particularly during lactation. Labor is a natural function, and happily the intervention of art is rarely demanded. But to foresee, prevent, or remove all possible dangers, to overcome serious obstacles when they exist, to resolve the many difficult and trying questions that may arise, demand skill and judgment. The important part which woman takes in generation consists in successive acts which are accomplished in her. One of the germs or ova, enclosed in the ovary, receives through impregnation the power to develop itself, and is then transported to the uterus. This organ retains the ovum, and furnishes it the materials for its growth. It becomes first an embryo, and next a foetus, when it acquires all the necessary powers for exterior life.

This succession of phenomena constitutes gestation or pregnancy. When these powers are acquired, the new being is expelled by a spontaneous action of the same organ which has contained, protected, and nourished it; and during this expulsion, known by the name of labor or parturition, in order to come to the light, it is obliged to traverse the pelvis, which is not accomplished without pain. But after its birth it still requires for some time the aid of the breasts, organs designed only for this function, which by the process of lactation furnish the necessary elements for its nutrition. The development of these phenomena is preceded and prepared for by particular modifications which the ovarian vesicles undergo. A bloody periodical discharge, called menstruation, of which the uterus is the source, ordinarily coincides with this modification of the ovarian vesicles.- Obstetrics then includes: 1, anatomy, the organs which concur to the execution of the acts above described; 2, the physiological phenomena, the mode in which these acts are performed; and 3, the pathology of these organs.

As regards the anatomy, it is sufficient here to say that the female organs subservient to generation are the ovaries, the principal function of which is the production of the ovule or germ; the Fallopian tubes, designed to receive the ovule and conduct it into the cavity of the uterus; the uterus or womb, a kind of receptacle, whose office it is to contain the fecundated germ during its period of development, and to expel it immediately afterward; and finally the vagina, a membranous canal extending from the neck of the uterus to the external organs. Most of these organs are situated within a large cavity, the walls of which are composed of bones and soft parts; this is termed the cavity of the pelvis. The functions of these organs are menstruation, conception, gestation or pregnancy, and labor or parturition. These functions are limited to certain periods of life, usually from about the 15th to the 45th or 48th year. The generative faculty in women coincides with the function of menstruation. The earliest age at which pregnancy is positively known to have occurred is 11 years; and the latest period at which parturition at the full term of gestation is recorded to have taken place is 64 years.

The most prolific period, according to Dr. Bland, is between the ages of 26 and 30 years. - The signs of pregnancy may be divided into two classes: 1, those which result from the derangement of some functions, as suppression of the menses, nausea and vomiting, mammary pains, vitiated tastes, etc.; 2, those which are to be detected only by a physical examination, as the change of color around the nipple, called the areola, the enlargement of the abdomen, the movements of the foetus, the position of the uterus in the abdomen, hal-lottement or repercussion, and the signs derived from auscultation, and those ascertained by touch, of the change in form, density, and position of the neck of the womb. There are some diseases which may give rise to an unjust suspicion of the existence of pregnancy, particularly those that produce enlargement of the abdomen. The chief of these are spurious pregnancy, a very curious and not very infrequent phenomenon, ovarian dropsy and dropsy of the abdomen, fibrous tumors and large polypi of the uterus, enlargement of the liver, kidney, spleen, etc, and distention of the cavity of the uterus with blood, water, or air. - It is usually admitted that the ordinary duration of pregnancy is ten lunar months, or about nine calendar months, or from 274 to 280 days; but it has long been a disputed point whether gestation may not be protracted beyond this period.

The weight of authority is now in favor of the opinion that it may in some instances be prolonged to the 300th and even the 306th day. The abrupt termination of pregnancy by the premature expulsion of the product of con-I ception is of frequent occurrence, the number of mothers who pass through the child-bearing epoch of life without ever aborting being small. The expulsion of the ovum may take place at any period of gestation. When it occurs during the first 16 weeks, it is termed an abortion; when between the end of this period and the 28th week, a miscarriage; and when after the latter period, but before the completion of the full term, a premature labor. When the foetus is expelled before the 28th week of pregnancy, it either dies immediately or soon after birth. The causes of abortion, miscarriage, and premature labor may be classified under five heads, viz.: 1, the accidental; 2, some deranged state of the mother's health; 3, some disease of the uterus or its appendages; 4, some disease of the embryo or foetus or its membranes; 5, when induced for criminal purposes, or necessary to preserve the life of the mother. The danger to the life of the mother depends somewhat upon the period when the abortion or miscarriage occurs.

In the first or second month the ovum with its appendages generally escapes without producing any noticeable illness. In the third and fourth months there is often considerable danger from haemorrhage. The danger then becomes lessened after the fifth month. When the abortion originates from some slowly operating maternal or fatal disease, it is attended with much less serious consequences than when it is produced suddenly by an accident, or by the exhibition of some irritating medicines, or by puncturing the membranes. Tardieu reports 34 cases of criminal abortion, 22 of which resulted in the death of the mother. So, too, an abortion occurring during the progress of an acute inflammation of the lungs, brain, heart, liver, or bowels, forms a highly dangerous complication. - The condition of pregnancy occasionally results in a salutary change in the entire system of the mother, better health being then enjoyed than at any other period. But in a majority it induces disagreeable symptoms, amounting merely to discomfort in some individuals; in others, so great as to injure the health and even destroy life.

The diseases of pregnancy are: lesions of digestion, as anorexia or loss of appetite, vomiting, sometimes so persistent as to destroy life, constipation, diarrhoea; lesions of the circulation, as plethora, hydrsemia, varices, haemorrhoids; lesions of the secretions and excretions, as ptyalism, albuminuria, anaemia, leucorrhcea, dropsy of the cellular tissue, dropsy in the great cavities of the body, dropsy of the amnion (a morbid collection of water in the uterus); lesions of locomotion, as relaxation of the pelvic articulations, inflammation of the pelvic articulations; lesions of innervation, as modifications of the organs of sense, blindness, deafness, vertigo, syncope, pruritus of the vulva; and displacements of the uterus. - Labor or parturition consists in the spontaneous or artificial expulsion of a viable foetus through the natural parts. Previous to the commencement of labor, some precursory phenomena appear, in some cases during the last fortnight of pregnancy, in others only five or six days before labor commences. They result from the dilatation of the internal orifice of the womb.

The uterus, which before extended up to the stomach, sensibly sinks lower, the mechanical obstruction to respiration is removed, the stomach is no longer oppressed, but the bladder and rectum become irritable, and locomotion is more difficult. The physiological phenomena of labor are divided into three stages: the first stage ends with the dilatation of the mouth of the womb, the second with the expulsion of the foetus, and the third with the delivery of the placenta or after-birth. The symptoms of the first stage are intermittent pains, resulting from the uterine contractions, discharge of a glairy mucus, formation of a bag of waters, and gradual dilatation of the neck of the womb. The pains of the first stage are usually borne with more impatience than those of the second. The cries which accompany them are sharp, and resemble those of any other species of suffering; those of the second stage seem to be suppressed like those of a person carrying a heavy burden. The use of the glairy discharge is to moisten and lubricate the parts over which the child has to pass, to increase their suppleness and extensibility, and make it more easy for the ovum to slide over the surfaces.

Where these discharges fail to take place, the dilatation of the mouth of the womb is always more painful and slower, and the organs are more disposed to become inflamed. The name of bag of waters is given to a protuberance formed by the membranes in the upper part of the vagina during labor. During the presence of a pain, it is hard, tense, and elastic; after the contraction is over, it becomes wrinkled and contracts or disappears. It eventually breaks, sometimes early in the first stage, and in other cases not until late in the second stage, when the contained fluid escapes. The duration of labor is exceedingly variable, even when no obstacle opposes its natural course. Some women are delivered in an hour or two, others only after several days; and between these two extremes there is every intermediate grade. In the first confinement, the average length of labor is usually from 10 to 12 hours; but in at least one case out of five it may not terminate under 15, 18, or even 24, and this without any injury whatever resulting either to the mother or child. Women who have had children are delivered much sooner, only suffering, in ordinary cases, about 6 or 8 hours. The duration of the first stage is to the second as 2 or even 3 to 1; but this law is subject to many exceptions.

The third stage ought to be completed within 30 minutes. - To understand the mechanical phenomena of labor, it is necessary first to define the terms presentation and position. We designate by the term presentation the part of the child that first offers at the entrance of the pelvic cavity; and by the term position, the relations of the presenting part to the different points of the entrance to the pelvis. The attitude of the child in the uterine cavity is in a great majority of cases such that the direction of the trunk is parallel with that of the mother, and one extremity forms the most dependent part. If the head is flexed, it is called a vertex presentation. If the head is extended back, the chin far removed from the breast, it is a face presentation. When the other extremity presents, the legs are usually flexed on the thighs and the latter on the abdomen; the whole breech may therefore offer at the entrance of the pelvis, or one or both feet or knees. As the mechanism of labor must be the same in all these cases, they are all ineluded under the term pelvic presentations.

But it may happen that, instead of one of the extremities offering, some portion of the trunk may offer, the child lying transversely in the uterus, and this may he either some point of the right half or of the left half of the trunk. We have then live primary presentations, one of the head, one of the face, one for the pelvic extremity, one for the right lateral plane, and one for the left lateral plane. The presentation of the head is incomparably more frequent than all the others. According to Mine. Boi-vin, in 20,357 cases it occurred in 19,730. The foetus presents by the face, on an average, once in 250 labors. The pelvic presentation occurs once in 30 or 35 labors. The trunk presentations are a little less rare than the face, occurring about once in 200 cases. As a law it may be said that trunk presentations always demand the interposition of art to accomplish delivery. The other presentations generally terminate spontaneously. In order that a labor may terminate without foreign aid, there must be on the part of the mother no fault or deformity of the pelvis, no serious affection of the womb, and the organ must possess a certain energy; the general powers of the system must not have been exhausted either by a profuse haemorrhage or any long continued disease; there must be no affection making it dangerous for the woman to give herself up fully to the efforts that she is compelled to make; and no accident must supervene during the labor.

On the part of the child, it is important that it should descend with the head, the face, the feet, the knees, or the breech foremost, and that it should not be of a size disproportionate to the capacity of the pelvis. About one case in 30 requires in some form artificial aid to complete a happy delivery. - The obstetric operations required for cases of difficult and dangerous labor, either to save the life of the mother or child or both, are: 1, induction of premature labor, an operation of great importance and value in certain cases; 2, version or turning, that manual operation by which one presentation is substituted for another less favorable; 3, the vectis, to correct malpositions or aid the natural rotations of the head; 4, delivery by forceps; 5, craniotomy, an operation by which the life of the child is sacrificed in order to save the mother; 6, the Caesarean section, in which the child is extracted through an incision in the walls of the abdomen and uterus. The dangerous complications which may arise in connection with labor are: prolapse of the cord or funis, an accident very fatal to the child; flooding or haeemorrhage; retention of the placenta; convulsions; rupture of the uterus; lacerations of the vagina or perineum; and inversion of the uterus. - The progress of obstetrical science and the improvement in the art have been very marked in recent times.

According to Tanner, "the 20th annual report of the registrar general of births, deaths, and marriages in England shows that in the year 1847 the birth of every 10,000 living children was the death of 60 mothers, whereas in 1857 it was only fatal to 42; hence 18 mothers arc now saved in every 10,000 children born. Since 1848 the decline has been progressive, the numbers per 10,000 being Gl, 58, 55, 52, 47, 47, 44, and 42 in 1857." Among the most striking modern improvements in obstetrical science and practice may be mentioned the application of auscultation to obstetrics; a more perfect knowledge of the mechanism of labor, and of the management of placenta praz-via; the introduction of anaesthetics; the induction of premature labor; an increased frequency in the use of the forceps, and a less frequent resort to craniotomy; and the substitution of version in cases where either craniotomy or the long forceps were formerly employed.