The breast is both factory and depot for milk. Milk is produced and stored in glands, which attach radially to a central nipple with 15–20 ejection ducts. An infant initiates the milk ejection reflex by grasping and deforming the nipple and areola. This not only causes milk release, but also sends a feedback signal to the pituitary gland causing a rise in serum prolactin and oxytocin levels. Serum oxytocin augments milk ejection by stimulating myoepithelial cells surrounding the milk glands to contract, forcing the milk into ducts within the nipples. Prolactin stimulates an increase in new milk production. The infant begins sucking as a series of rapid compressions, which enhance milk ejection, then slows to a sucking/swallowing rhythm. In the absence of active sucking, the nipple regains its compact shape and thus will not drip continuously. It is during this phase that the infant will be able to swallow effortlessly. This is in contrast to the manufactured rubber nipple, which maintains a continuous flow throughout the feeding cycle. An infant feeding from a bottle must compress his/her lips or perform a tongue thrust to interrupt this flow and allow unimpeded swallowing. The differences in milk delivery between bottle and breast nipples form the basis for “nipple confusion” in which the infant cannot distinguish which type of activity will result in comfortable swallowing.

While milk letdown may be a reflex, the act of breastfeeding is complex and all women can benefit from instruction in the proper technique. Breastfeeding is best initiated in a quiet, stress-free environment. Special consideration should be given to positioning, latch-on, and nipple care. Adequate nutrition, rest and fluid intake are needed to maintain milk supply. A lactating woman needs approximately 300 kCal/day above her maintenance caloric requirement. She should also drink adequate amounts of fluid; however, increased intake will not solve problems of milk production. If weight loss in excess of 1 lb (0.45 kg) per week occurs, caloric intake should be increased.

When initiating breastfeeding, one must first assure the baby is alert and ready to feed. Infants who have been given formula in the nursery while the mother is recovering may not readily initiate suckling. Acceptable strategies to awaken a baby include cheek strokes, back rubs, tickling the feet, and undressing an infant to improve skin-to-skin contact. Several positioning holds have been described, with the most common being the cuddle hold and the football hold. The cuddle hold supports the infant along the length of the forearm, crossing the maternal abdomen while using the contralateral hand to position the breast near the infant’s mouth. The football hold presents the ipsilateral breast to the infant while supporting the infant along the side. The football hold has advantages when the breasts are especially pendulous or during feeding of twins. In all cases, the use of a nursing pillow helps the mother decrease strain along the upper back and neck.

Proper latch-on occurs when the baby grasps the nipple and areola, pressing its nose directly up to the breast. Painful latch-on is tantamount to recognition of improper latch-on or sucking. Once latch-on has occurred, the infant initiates a series of quick suckling motions that stimulate a “pins and needles” sensation of milk letdown. A baby should be encouraged to nurse for at least 10–15 minutes at each breast during a feeding. Once satiated, the infant will cease suckling, but may hold the nipple lightly to maintain contact. Breastfeeding can occur “on demand” or on schedule, but most infants respond best to an on-demand system. As many delivery units have adopted policies encouraging the baby to room in with the mother, the popularity of “on-schedule” nursing has declined.

After nursing, women should be encouraged to express some residual breast milk onto the nipple and areola and allow the area to air-dry for a few minutes. The immunoglobins in the milk protect against cracking and dryness, and air-drying prevents yeast infections. Women should be cautioned against using creams or lotions. Often, these preparations clog milk ducts and carry a perfume or taste which is unappealing to the infant.

Once an infant masters sucking and latch-on, the prognosis for success over the next 2–4 weeks is good. Unfortunately, minor problems during this time period can evolve as barriers to continued breastfeeding if the mother does not receive advice to overcome them. In addition to the physician, there are several resources available. Most delivery units have trained lactation specialists who will assist with telephone advice or home visits. Most metropolitan areas boast several commercial businesses as well as free support groups to assist with questions about breastfeeding.

Problems of supply and demand

Most commonly, imbalances in supply and demand occur during the initiation period of breastfeeding, during infant growth spurts and after 6 months of lactation. During the first 1–3 days post partum, most women do not experience breast fullness or sensation of letdown when nursing. This leads to the understandable concern that the baby is not receiving nourishment and needs supplementation with bottle feeding. Bottle feeding at this time interferes with establishment of breastfeeding by inducing nipple confusion and by decreasing suckling time at the breast. Women should be reassured that as long as the baby is nursing every 2–3 hours and five or six wet diapers are noted each day, supplementation with bottle feeding is not necessary. If supplementation is indicated, it should occur after at least 10–15 minutes of suckling efforts at the breast.

After about 3 days, normal breast fullness occurs which can progress to engorgement. Proper therapy for engorgement includes frequent nursing, gentle breast massage during nursing, and attention to proper latch-on technique. Acetaminophen or ibuprofen may be used if desired. An overabundant milk supply may be noted in the first 2 months, before the breasts soften and enlarge to contain milk production.