The term “human milking” refers to expressing milk from the breast, typically to feed an infant or manage the milk supply. This practice ensures the baby receives the nutritional benefits of human milk even when direct feeding is not possible. Understanding the mechanics of milk production and removal is essential for effectively providing this optimal source of nutrition.
The Biological Mechanism of Lactation
Human milk production and release are governed by a hormonal sequence initiated after childbirth. The synthesis of milk components is primarily the responsibility of prolactin, released from the anterior pituitary gland. Prolactin acts on the alveolar cells, stimulating them to manufacture the milk’s proteins, fats, and lactose.
For milk to be removed, the milk ejection reflex, or “let-down,” must occur. This reflex is triggered by oxytocin, released from the posterior pituitary in response to nipple stimulation. Oxytocin causes the contraction of myoepithelial cells surrounding the alveoli, forcing the milk into the ducts and toward the nipple.
Once lactation is established, milk volume shifts to a localized, supply-and-demand system known as autocrine control. Frequent and complete removal signals the breast to continue production. If milk remains, a protein factor signals the cells to slow down synthesis, regulating the supply to match the demand.
Clinical Reasons for Expression
Milk expression is necessary when direct feeding is temporarily or permanently challenging. This occurs when an infant cannot effectively remove milk due to prematurity or medical conditions. Separation of the parent and baby, such as when a newborn requires care in a Neonatal Intensive Care Unit (NICU), also necessitates expression to provide the baby with milk.
Frequent expression is a strategy used to establish or increase milk supply by stimulating higher prolactin levels. Therapeutic expression manages common discomforts like engorgement, which makes latching difficult. Expressing milk also allows other caregivers to feed the baby, offering flexibility when the parent is absent.
Manual and Mechanical Expression Techniques
Milk can be removed through hand expression or by using a mechanical pump; both methods require specific techniques for maximum effectiveness. Hand expression is useful in the early postpartum days for collecting colostrum, which is thick and difficult for a pump to draw out. The technique involves forming a “C” shape with the thumb and fingers behind the areola, then using a rhythmic motion of pressing back toward the chest wall, compressing the tissue, and releasing.
Mechanical expression typically involves a pump, with double electric pumps being the most efficient as they stimulate both breasts simultaneously. To establish a full supply, experts recommend aiming for eight to ten expression sessions every 24 hours, mimicking a newborn’s feeding frequency. Each session should last 15 to 20 minutes, or until five minutes after milk flow has stopped, to ensure adequate breast drainage and continuous supply stimulation.
Proper flange sizing is important for pump users, as an improperly sized flange can cause discomfort and reduce milk output. The flange, which is the cone-shaped part that fits over the breast, must be correctly sized. This ensures the nipple moves freely within the tunnel without the areola being excessively pulled in, allowing for comfortable and thorough emptying of the breast.
Guidelines for Safe Handling and Storage
Once milk is expressed, proper handling is necessary to maintain its safety and nutritional integrity. All pump parts and collection containers that come into contact with milk must be thoroughly cleaned after each use. This process involves:
- Disassembling parts.
- Rinsing them.
- Washing them in a dedicated basin with soap.
- Air-drying them.
Sterilization, such as boiling parts or using steam sterilizers, is recommended, especially for parts used by high-risk infants.
Expressed milk should be stored in clean, food-grade containers, such as specialized bags, glass bottles, or BPA-free plastic containers. Freshly expressed milk can safely remain at room temperature (up to 77°F) for four hours, or be refrigerated for up to four days. For longer storage, milk can be kept in a standard freezer for about six months, though up to twelve months is acceptable.
When freezing, label the container with the date and leave about an inch of space at the top, as the liquid expands. To thaw frozen milk, place it in the refrigerator overnight or run it under warm water. Milk should never be thawed or warmed in a microwave, as this can create dangerous hot spots and reduce nutritional quality.