Lactation is the biological process of milk production, driven by hormones and physical stimuli. A consistent milk supply relies primarily on the supply-and-demand feedback loop. When milk supply significantly decreases or ceases, often described as “drying up,” it signals a disruption in this delicate balance. This change can be gradual or sudden, stemming from mechanical issues in milk removal, underlying health conditions, or external factors like medication and stress. Understanding the specific cause of a faltering supply is the first step toward addressing the challenge.
Issues with Milk Removal and Supply Demand
The most common reason for decreased breastmilk production relates directly to the frequency and completeness of milk removal. Milk production operates on a local control mechanism after the initial hormonal surge subsides. When milk remains in the milk-making cells (alveoli) for extended periods, a protein called Feedback Inhibitor of Lactation (FIL) accumulates. This accumulation signals the body to slow down production, ensuring the volume produced aligns with the volume removed.
Infrequent feeding or pumping sessions, especially early on, quickly lead to a downregulated supply. Newborns typically need to feed 8 to 12 times in 24 hours to establish a full supply. Spacing sessions too far apart signals the breast that less milk is needed, causing FIL concentration to rise and production to decrease. Feeding based on the baby’s hunger cues is recommended for building a robust supply.
Ineffective milk removal disrupts the demand signal, even if feeding frequency is adequate. An improper latch means the baby is not efficiently transferring available milk, leaving the breast inadequately drained. Infants with a tongue-tie or a weak suck may also struggle to compress the milk ducts fully, leading to residual milk and suppressed production signals. For mothers who pump, using incorrectly sized flanges or low vacuum settings results in poor milk expression, mimicking ineffective removal.
Supplementing feeds with formula inadvertently suppresses the supply-and-demand cycle. Each formula bottle replaces a nursing session, reducing the stimulation and milk removal required to maintain volume. This reduction signals the body to lower prolactin receptor activity and increase FIL, causing the milk volume to drop. Additionally, pacifiers, particularly in the early weeks, can delay a baby’s feeding cues, resulting in fewer nursing sessions and less breast stimulation.
Hormonal and Physiological Factors
Internal maternal health conditions and anatomical variations interfere with the hormonal pathways necessary for milk synthesis. Secretory activation, the transition to copious milk production, is triggered by the sharp drop in progesterone after placental delivery. If placental fragments remain in the uterus, they continue to secrete progesterone. This prevents prolactin from fully activating the milk-making cells, resulting in a delayed or absent onset of mature milk.
Endocrine disorders involving hormone imbalances can impair milk production. Polycystic Ovary Syndrome (PCOS) is associated with insulin resistance and excess androgens, which negatively affect milk-making tissue development and hormonal response to lactation. Similarly, hypothyroidism (underactive thyroid) can reduce milk volume because thyroid hormones support milk synthesis signaling. Correcting these underlying hormonal issues with medical treatment can often improve a compromised supply.
Anatomical differences in breast structure can limit milk production capacity from the outset. Insufficient Glandular Tissue (IGT), or mammary hypoplasia, is a condition where the breasts lack enough milk-producing tissue to meet the infant’s needs. This structural limitation is often characterized by visual cues like widely spaced or asymmetrical breasts. Past breast surgeries, particularly reduction mammoplasty, can also damage milk ducts, nerves, or glandular tissue, permanently impacting the volume of milk produced.
When a new pregnancy occurs while nursing, the resulting hormonal shift can diminish the milk supply. The rise in progesterone and estrogen from the developing placenta suppresses prolactin’s action on the mammary glands. This often leads to a noticeable drop in milk volume. This natural suppression effect prepares the body for the next pregnancy.
Medications and Environmental Influences
External factors, including pharmaceutical agents and lifestyle stressors, can interfere with established milk production. Certain medications suppress prolactin, the hormone responsible for milk synthesis. Hormonal contraceptives containing estrogen are a common example, as estrogen counteracts prolactin’s action. These contraceptives can significantly reduce milk volume, especially if introduced before the supply is well-established.
Over-the-counter decongestants containing pseudoephedrine are recognized as potential milk supply suppressors. Pseudoephedrine acts as a vasoconstrictor and can decrease milk production, possibly by lowering prolactin levels. Furthermore, dopamine agonists, such as cabergoline, are specifically prescribed to intentionally stop lactation by inhibiting prolactin secretion.
The body’s response to stress is a significant environmental influence on milk flow. Stress, anxiety, or pain can trigger the release of adrenaline and cortisol, which inhibit the release of oxytocin. Oxytocin causes the myoepithelial cells to contract, initiating the milk ejection reflex, or “let-down.” When this reflex is inhibited, milk cannot flow easily, leading to poor removal and a subsequent drop in supply.
Severe dehydration or acute nutritional deficiency can negatively affect the ability to maintain a full volume of milk. While extra water does not increase production in a well-hydrated person, dehydration reduces the fluid volume available for milk synthesis. Adequate calorie and nutrient intake is necessary to support the energy demands of lactation, and severe restriction can compound factors leading to a decreased supply.