Lactation

LACTATION (Latin lactatio—suckling), the secretion of milk by the mammary gland. From the 2nd to the 3rd month of pregnancy, hyperplasia of the glandular parenchyma of the mammary gland begins (for its structure, see Mammary gland), continuing throughout the entire pregnancy. There are various theories explaining the cause of mammary gland growth during pregnancy and the onset of lactation after childbirth. All of them agree that the activity of the mammary glands is excited not by nerve impulses originating from the pregnant woman's genital sphere, as was thought earlier, but by chemical changes in the blood under the influence of hormones circulating in it, produced by the placenta (Halban, Basch) or the fetus (Starling, Biedl). According to Czerny, hormones produced by the pituitary gland, the thymus gland, and the corpus luteum also influence lactation. The question of whether ovarian hormones have any influence on the hyperplasia of the mammary glands during pregnancy remains unresolved to this day: while some authors completely deny any role of the ovaries here, others attribute an exclusive influence on the development of the mammary glands to the hormones produced in them. In any case, it has been established beyond doubt that the same growth impulses can also come from the egg (placenta and embryo). The theory of Hildebrandt and Schein stands apart, according to which substances are formed in the woman's body during pregnancy that serve to nourish the fetus; after childbirth, these nutrients concentrate in the mammary gland and serve as the material from which milk is produced. Finkelstein, combining the hormone theory and the nutrient theory, allows for the possibility that hormones stimulate the growth of the mammary glands during pregnancy, and the rapid accumulation of nutrients in the glands after childbirth causes lactation. The influence of hormones on lactation is proven by a classic example: when one of the conjoined Blazek twin sisters became pregnant and gave birth to a child, noticeable milk secretion was discovered in the other. Obviously, through the circulatory system common to both sisters, the hormones produced in the pregnant woman's placenta or in the fetus reached the mammary glands of the other sister. It is interesting that during childbirth, a certain amount of placental hormones enters the child's circulatory system; they also act specifically here on the newborn's mammary gland, causing its swelling and the secretion of colostrum (the so-called Hexenmilch, or witch's milk) in both boys and girls. According to the observations of Basch, confirmed by Czerny, strong secretion of the mammary glands in a newborn gives reason to assume that the mother will have plenty of milk. Lactation, the appearance of which is caused by hormones, is then maintained by the regular suckling of the child. On the first day after childbirth, a few drops of colostrum (see) can be squeezed from the breasts. Subsequently, the increase in secretion occurs differently. In some cases, the breasts gradually swell, the amount of milk increases every day, and by the 4th–5th day, lactation is in full swing. In other cases, the rush of milk occurs suddenly and violently; on the 3rd–4th day after childbirth, the breasts become very hard within a few hours and increase significantly in volume; dilated veins show through the shiny, tense skin, severe pain appears in the breasts, and the temperature rises. This state lasts for 1–2 days, after which, if the breast is energetically emptied, normal lactation is established. Sometimes, mainly in primiparas, a late appearance of milk is observed: secretion begins only on the 5th–6th day and even at the beginning of the 2nd week and develops slowly by the 3rd week. From the moment of the milk rush, secretion gradually and continuously increases, reaches its maximum between the 10th and 20th weeks, and remains at the reached height until the end of the lactation period (for cases of insufficient lactation or its early cessation, see Hypogalactia). The amount of milk in the same woman can undergo certain fluctuations on different days and at different hours of the same day (there is more milk after a night's rest, and less after a sleepless night, as well as towards the end of the day after strenuous work), but in general, it is approximately the same within a 24-hour period, increasing from 200–300 g in the first week to 900–1,200 g at the height of lactation. The absolute height of the latter depends, on the one hand, on the individual characteristics of the structure of the mammary glands, and on the other hand, on the demand placed upon them. There are mammary glands rich in connective tissue and poor in glandular parenchyma, and, conversely, glands with strong development of parenchyma and weak development of connective tissue. Better or worse lactation depends mainly on the greater or lesser development of the parenchyma, which is determined to a large extent by heredity and racial and living conditions: Russian women are generally distinguished by better lactation ability than Western European women; in the USSR, Jewish, Tatar, Kyrgyz, and other Eastern women have better ability than Russian women; peasant women have better ability than urban women. However, even a breast rich in parenchyma that has not functioned for a long time may, due to atrophy of the parenchyma, produce little milk after childbirth. This probably explains the poor lactation in older primiparas and in multiparas when a long interval passes between the birth of one child and another. In the presence of a good mammary gland in the sense indicated above, its production is greater the greater the demands placed upon it, and in cases where a wet nurse feeds 2 or more children, it can reach 2,000–3,000 g (and more) per day. Phenomenal lactation cases are described in the literature. Thus, Brodski describes a 25-year-old wet nurse whose milk production reached 5,400 g per day; over 339 days, she produced 1,193 liters of milk. Kollmann observed a 23-year-old wet nurse at the Augsburg Foundling Home who, on the 51st day, produced over 4,000 g of milk, on the 146th day up to 5,000 g, and fed 7 children. One cannot judge what lactation will be like in the future based on the amount of milk in the first period after childbirth. The minimal amounts of milk at the beginning can gradually increase, in any case enough to make mixed feeding possible; it is not uncommon for breasts that are poor in milk at first to begin to function perfectly after a few weeks. In general, it is impossible to predict in advance whether a mother will be a good wet nurse or not; neither the state of general nutrition, nor the appearance of the mammary gland, nor its palpation allow one to judge a woman's lactation ability with certainty. Very often a pale, thin, weak mother turns out to be an excellent wet nurse, while a healthy, well-nourished woman shows poor lactation (inopia lactis). It is generally accepted that well-developed breasts with a small deposit of fat and an abundant venous network showing through the skin, with protruding glandulae Montgomerii and with tense nipples, serve as a sign of good lactation ability. But this view is far from being confirmed by experience in all cases: sometimes perfectly developed breasts contain little milk, and a woman with small, flat breasts that do not protrude much above the surface of the chest wall gives relatively large amounts of milk. Moll's indication of a higher temperature under the mammary gland than in the axilla (the difference reaches 0.4–1°) as a good prognostic sign in terms of a woman's lactation ability is refuted by the studies of Jaschke, as well as Dyroff. No matter how little milk a mother has in the first days, it is necessary to systematically put the child to the breast. If the child sucks strongly, then the act of suckling itself is the best means for increasing secretion; otherwise, after feeding the child, one must extract all the milk remaining in the breast with an apparatus (see Breast pump) or express it by hand. It is important to calm the mother and convince her that milk will appear in sufficient quantity in a few days and that she will be able to nurse her child. The adequacy of lactation is determined on the one hand by the child's good weight gain, and on the other hand by the duration of the period during which the mother can feed only with the breast, without resorting to mixed feeding. Since the child should receive the first supplementary food in the 6th month, lactation should be considered sufficient if the child's needs are fully covered by the mother's milk until the end of the first half-year. In contrast to what is observed in dairy animals (cows, goats), in which the quality and quantity of milk (of course within certain limits) are related to the food ration, lactation in women depends on nutrition only within very limited limits. Abundant milk drinking and very nutritious food (cream, lots of butter, eggs) not only do not contribute to the strengthening of lactation but often, on the contrary, lead to a decrease in milk secretion: general obesity and the deposition of a large amount of fat in the mammary glands occur, accompanied by a decrease in the glandular parenchyma and, consequently, a decrease in lactation. On the other hand, only very prolonged malnutrition leads to a decrease in the amount of milk. Many means have been proposed to increase secretion, but none of them has a specific effect on the mammary gland.

All more or less energetically advertised milk-producing preparations (Lactogoga), such as lactagol (a vegetable protein preparation containing the globulin edestin and representing a dry extract from cottonseed), polylactol (a preparation of somatose, malt, and galactose), galega (a plant whose preparations—decoction and extract—are used in folk medicine), somatose, sanatogen, roborat, malt tropon, maltil, biomalt, do not in themselves exert a stimulating effect on the activity of the glands; at best, they act psychogenically on the nervous, desperate mother, whom one manages to convince that this or that preparation will cause an increase in lactation, and thereby lift her spirits and mood. No better results are obtained from the application of massage of the mammary glands, proposed by Rommel and Pfaundler, Bier's passive hyperemia (Moll, Jaschke), or diathermy (Seitz, Vey). Duncan and C. Meyer recommended subcutaneous injection of the mother's own milk. Upon verification of this method by other authors, the results were contradictory, and it must be viewed as a general Reizkörpertherapie, which does not act specifically but sometimes provides some, moreover short-lived, increase in milk secretion. Theoretically, the most well-founded and promising are experiments in increasing lactation in animals via subcutaneous injection of placenta extract (Gorizontov and others). In view of the small number of such experiments on humans and the contradictory nature of the results noted by various authors, at the present time it is not yet possible to make a definitive statement about this method of increasing lactation. Experiments were also made using other organotherapeutic preparations (thyroidin, pituitrin, corpus luteum extract of the ovaries, thymus gland); the results were inconsistent and in any case very short-lived. In 1927, Stolte described excellent results obtained by him from quartz lamp irradiation of the mammary glands of women suffering from hypogalactia. But Freund and other authors, who tested this method on significantly larger material, proved that it, too, is ineffective in cases of insufficient development of the glandular parenchyma. As long as no specific remedy is found, the only reliable method for maintaining and increasing lactation must be considered the regular and complete emptying of the mammary glands by the sucking infant or by artificial means (breast pump, manual expression). With incomplete emptying of the breast, milk stasis occurs, and under the influence of changed conditions of pressure and blood circulation in the mammary gland, damage to the secreting epithelium occurs, and milk production gradually decreases, with colostrum bodies appearing in it. If milk stasis reaches a high degree, the breast becomes tense, painful, and the temperature rises (milk fever). By applying a strong-sucking infant to the breast or by suction via a breast pump and light massage, it is necessary to empty the breast as quickly as possible, after which the indicated phenomena pass. The duration of lactation fluctuates within wide limits and depends on the individual characteristics of the mammary gland and on how long a demand is placed on its work. Secretion weakens as the child begins to be given supplementary feeding and the use of the breast decreases; on the other hand, if the woman does not stop nursing and applies the child several times a day, the function of the mammary gland can be maintained for a number of years. Among Eastern and Southern women, lactation continues for 3–4 years, among Europeans—on average about 1 year; but cases of much longer lactation are known. Finkelstein observed one wet nurse who, even in the 19th month after childbirth, gave an average of 1,500 g of milk per day, and another who, in the 25th month, gave up to 1,700 g of milk per day; both women stopped nursing not because of the cessation of lactation, but of their own volition. De Rudder reports on a wet nurse who gave up to 3 liters of milk per day for more than 3 1/2 years. In Birk's clinic, there was a wet nurse who gave 2 liters of milk for 3 years, and over the entire time gave 2,167 liters. Sometimes a mother, for one reason or another (severe illness, temporary departure, etc.), does not nurse the child for a more or less prolonged time. In these cases, if the physician considers it necessary to return the child to breastfeeding, it is possible by persistent and regular application of the child to the breast to restore lactation (relactatio) even after the passage of several weeks. Menstruation, which is observed in approximately half of nursing women, either does not affect lactation at all or affects it so weakly that it has no practical significance: sometimes during this period secretion decreases slightly; much more rarely, the child has mild dyspepsia, which usually ceases in 2–3 days. As for a new pregnancy, in the first 3–4 months it does not affect lactation at all, and in the second half it usually causes a decrease in the amount of milk. However, quite a few cases are observed where sufficient lactation is maintained throughout the entire pregnancy, and the mother, having finished nursing one child, begins to nurse another child without a break and feeds it well. The mother's mental state has an undoubted influence on lactation; this is best confirmed by a natural experiment, which the last war presented on a very large scale. According to the observations of a whole series of Russian and Western European authors, the lactational capacity of women in these years noticeably decreased, which must be attributed solely to the severe experiences associated with the presence of their fathers, husbands, and brothers at the front. Under the influence of a sudden mental shock, e.g., unexpected news of the death of a loved one, milk secretion in a nursing woman may temporarily cease. Here the issue is not a cessation of secretion, but that due to a strong contraction of the sphincter, the child cannot suck out a single drop of milk. Such cases are observed rarely and represent a transient phenomenon: as soon as the influence of the shock weakens, the spasmodic contraction of the sphincter also weakens, and nursing continues as before. Medicinal substances taken by the nursing mother generally do not affect lactation; one should only avoid senna leaves and mineral laxatives, which, due to the large loss of water they cause, may temporarily result in a decrease in secretion. A decrease in lactation is observed in all chronic, debilitating diseases (diabetes, nephritis, cancer, etc.), in acute diseases with high temperature and loss of appetite, in chronic infections, among which tuberculosis must be placed in the first place, as well as in diarrheal diseases of the mother. The question of the influence on lactation of the mother's work in hazardous production has so far been little developed; there are only some indications of a decrease in lactation in women working in tobacco factories and in industries where they are poisoned by lead dust.

A. Gershenzon. Pathological lactation. The concept of pathological lactation includes, on the one hand, cases of lactation resulting from true hypertrophy of the mammary glands in men, often with the secretion of a significant amount of fluid, and on the other hand, cases of female secretion when the latter is not associated with the usual physiological states of a woman—pregnancy, nursing, or menstruation; in most cases, this concerns the secretion of a fluid that is closer in its chemical and morphological nature to colostrum than to milk. Engorgement of the mammary glands in boys during puberty, then the so-called mastitis of newborns, and cases of mammary gland secretion in women during the climacteric period should not be included in the concept of pathological lactation and are currently considered a physiological process (Kestner, Litten, and others). Pathological lactation in many of its forms can also occur in animals. Cases of pathological lactation can be classified as follows. 1. Cases of pathological lactation in men. This also includes rare but entirely reliable observations of men nursing children (Hackel, Humboldt, and many others). These cases are currently, for the most part, accepted by the majority of authors as gynecomastia. 2. Cases of female pathological lactation observed during castration. Cases of secretion during genital tumors, mainly ovarian cancers, can apparently also be attributed to this. 3. Cases of pathological lactation during pituitary tumors. These cases can be observed in individuals of both sexes and are often accompanied by other changes of a special nature—acromegaly, adiposogenital syndrome. 4. Cases of pathological lactation during inflammatory processes in the area of the mammary glands. Cases of extremely prolonged nursing in women and cases of hypertrophic female lactation should also be attributed to pathological lactation. The macroscopic and microscopic picture of the mammary glands during pathological lactation can vary depending on the degree of hyperplasia and secretion of the organ and ranges from the pictures observed in gynecomastia (see) to a complete resemblance to the gland of a nursing woman. The pathogenesis of pathological lactation has not yet been considered studied. Gynecomastia, which lies at the root of one of the types of pathological lactation, is viewed by the majority of authors as a kind of feminization developing secondarily in response to macro- or microscopic changes in the gonads. Unfortunately, many interesting cases of gynecomastia without testicular involvement, especially those described by earlier authors, were not accompanied by histological examination and are considered unproven. Experimental data obtained by Steinach on rats after feminization, i.e., by changing sex characteristics, seem to convince one of the correctness of the stated view on gynecomastia; upon transplantation of ovaries to castrated males, the latter experience hyperplasia of the glandular tissue of the mammary organ and its function; normal, fat-rich milk is squeezed from the nipples. Such feminized males can nurse and indeed do nurse their young. These observations were also verified on deer. Contradicting this point of view are cases of hypertrophy of the mammary gland parenchyma and often abundant secretion from them during castration in women. Also not rare are cases of secretion in women, as indicated, during tumors (cancers) of the ovaries. In veterinary medicine, the fact of the influence of castration on the mammary glands is well known and has even found practical application. Thus, cows are castrated in the 8th–9th year after the cessation of lactation, and this acts like pregnancy. According to literature data, it must be considered proven that the growth of the mammary glands and their secretion can exist independently of ovarian hormones. Frenkel's studies showed that castration after a 2–3-week period of pregnancy has no influence on the growth of the mammary glands, the course of pregnancy, and subsequent nursing. Forensic medicine knows well that the presence or absence of mammary glands is not always an indicator of sex; thus, they were absent in some undoubted cases of female hermaphroditism, and conversely, in Ekaterina Goman (Klebs's case), they were present despite proven semen production. Interesting here are also cases from the animal world; thus, Haenel describes lactation in a goat that successfully covered 60 goats, with his daily amount of milk being 0.74 liters and not differing from the milk of goats. Among a large number of organs, extracts from which have a stimulating effect on the growth and secretion of the mammary glands, great attention in the question of the pathogenesis of pathological lactation must be paid to the pituitary gland. Cases of pathological lactation during pituitary tumors are in this respect extremely valuable in terms of solving the problem of the pathogenesis of pathological lactation and lactation in general.

A. Kestner. Lactational psychoses—mental disorders occurring in women during the period of lactation, especially often in the 3rd month after childbirth. Lactational psychoses do not represent a specific disease form, but include mainly attacks of schizophrenia and manic-depressive psychosis, and much more rarely, outbreaks of true amentia. The basis for grouping lactational psychoses into one category is the actually observed, although expressed in very small figures (1.6% of all mental illnesses in women), increase (compared to the average incidence) in the number of psychoses in women who are breastfeeding. The cause of this increase, however, is apparently not factors associated with lactation itself (old authors blamed the arrival of milk and exhaustion from nursing), but rather the state of unstable equilibrium in which the organism of a nursing woman, shaken by childbirth, remains for some time even after the puerperal period has passed. This corresponds to the fact that the number of lactational psychoses decreases rapidly in the later months of lactation, as well as the fact that lactational psychoses are especially frequent in multiparous young women who are recovering poorly from one pregnancy to another. Some authors do not even make a distinction between truly nursing and non-nursing women, attributing to lactational psychoses all psychoses that develop during the period from 6 weeks to 9 months after childbirth.