Galactogenesis is the infusion of milk into the mammary gland ducts that occurs during the postpartum period after pregnancy. Galactogenesis is a condition of lactation reflexes. Unlike lactation disorders, disorders of galactogenesis are not due to faulty breastfeeding but are usually due to excess placental steroid hormones.
What is galactogenesis?
Galactogenesis refers to the infusion of milk into the mammary gland ducts that occurs during the postpartum period after pregnancy. Lactation is the term used to summarize all the processes by which a woman produces milk during pregnancy to nourish her offspring. The so-called milk production reflexes or lactation reflexes play the main role in this process. These are hormonally controlled glandular activities in response to an external stimulus. In this case, the stimulus that causes this is primarily the touch stimulus that the sensory cells of the female breast register as a result of the baby’s sucking activity. Milk production is stimulated by the release of the hormone prolactin from the anterior pituitary gland. In turn, milk ejection is controlled by the hormone oxytocin. Galactogenesis specifically refers to the initiation of milk formation processes. Thus, galactogenesis predominantly corresponds to hormone release and hormone binding to the mammary glands. Galactogenesis and lactogenesis are closely related, but not synonymous. Lactogenesis is the preparation of the mammary glands for milk production during pregnancy and is hormonally triggered by estrogen. Galactogenesis, on the other hand, refers to post-pregnancy processes that result in the initiation of milk into the breast through prolactin and oxytocin release. Thus, galactogenesis begins immediately after the birth process and is often referred to as the initiating process of milk secretion. The further maintenance of lactation during the postpartum period is called galactopoiesis. Galactokinesis corresponds to milk let-down.
Function and task
With milk production and secretion, the woman has a natural means of feeding her offspring. Even during pregnancy, the hormones estrogen and progesterone affect the activity of the mammary glands. Placental steroid hormones have an inhibitory effect on milk production during pregnancy. For this reason, only so-called colostrum is produced during pregnancy, mainly under the influence of prolactin. After the rejection of the placenta, i.e. immediately after the birth of the child, milk production is no longer inhibited by placental steroid hormones. Milk is stored in individual areas of the glands and glandular ducts. After the birth of the infant, galactogenesis begins. This stimulates the secretion of milk in the glandular ducts. The stored milk is thus made available. This occurs primarily under the uninhibited influence of the hormones prolactin and oxytocin. Oxytocin is released in large quantities during the birth of the child as soon as the unborn child descends from the uterus, exerting pressure. The pressure stimuli are registered by sensory cells of the sense of touch and report the stimulus to the central nervous system by means of bioelectrical excitation via afferent nerve pathways. At this point, the reflex arc is interconnected with the glands. By wiring the excitation to motor nerve pathways of the glands, the milk letdown is initiated. By about the second or third day of puerperium, the blood level of placental steroid hormones is at a minimum. This results in the shooting of milk into the milk ducts, corresponding to the peak of galactogenesis. To maintain milk production during puerperium, new touch stimuli are required, which again result in increased oxytocin production. The touch stimuli for galactopoiesis correspond to the suckling stimuli of the newborn at the maternal breast. Thus, the ultimate milk production depends on the infant’s demand for milk. The more frequently the infant is latched on for breastfeeding, the more milk is produced.
Diseases and medical conditions
Disorders of lactation reflexes are often due to faulty breastfeeding behavior. This is not true for disorders of galactogenesis. Galactogenesis, unlike lactation, does not depend on contact between mother and child.In the narrower sense, it is not a reflex process that must be preceded by a specific stimulus. A disturbance of galactogenesis occurs when the placental steroid hormones continue to have an inhibitory effect on the mammary glands. This may be the case, for example, if the placenta does not detach or detaches incompletely after birth. As a rule, an incompletely detached placenta is brought to detachment via curettage. Thus, in the Western world, it is rare for the placenta to remain within the body. Since placental residue can cause hemorrhage and, in addition, often degenerates, obstetricians check and support placental detachment by all means. Elevated progesterone levels are also present in ovarian tumors, bladder mole, or adrenogenital syndrome. Adrenogenital syndrome is a genetic defect of enzyme 21-hydroxylase, which results in decreased production of cortisol. As a consequence, the blood level of cortisol precursors increases, which in turn correspond to steroid hormones. Also, when the level of luteinizing hormone is elevated, too much progesterone is produced after pregnancy, causing disturbances in galactogenesis. Prolactin and luteinizing hormone are interrelated. For example, when prolactin levels are high, luteinizing hormone is inhibited. On the other hand, if prolactin levels are too low due to a disease of the pituitary gland, high levels are present. Prolactin deficiency may be associated with damage to pituitary tissue, for example.
