The let-down

What is a let-down?

Let-down is the process that leads to the delivery of milk to the baby. Milk is made and then stored in tiny milk sacs until the baby is hungry. When the baby starts to breastfeed, the body sends a signal to a gland (the pituitary) at the base of the brain. The gland releases a hormone (oxytocin) that causes muscles around the milk sacs to squeeze, sending milk into the ducts of the breast and towards the nipple. Let-downs happen several times during each breastfeeding but can also happen simply when the breasts are full. They can be painful, or they may not be felt at all.

A) Describing the let-down

Milk is made and then stored in tiny sacs (alveoli) until the baby is hungry. The let-down, also called the milk-ejection reflex, is a process that starts with the baby breastfeeding. This results in the following:

  1. The body sends a signal to the pituitary gland at the base of the brain.
  2. The pituitary gland releases the hormones oxytocin and prolactin.
  3. Oxytocin causes the muscles around the alveoli to squeeze (Matthiesen 2001).
  4. This sends the milk into the 5 to 25 (average 9) milk ducts in the breast (Geddes 2007).
  5. The squeezing on the alveoli and the vacuum created by the baby’s tongue and lower jaw work together to deliver milk to the baby.

The average number of let-downs per breastfeeding is 2.5, with a range of zero to nine. During expression, the average number of let-downs is between 3 and 6 for every 15 minutes (Geddes 2007).

Let-downs can cause leaking and spraying from the nipples if the baby is not latched.

Let-downs can deliver milk quickly and normal babies will occasionally choke on the milk. 

B) Timing of the let-down

1) Normal let-down

The let-down happens with the start of breastfeeding, but it can also happen at other times. This may be when the breasts are full, physically stimulated, when mothers think of their baby, or hear another baby cry. 

In the first days after delivery, mothers often notice cramping pain from the uterus at the same time they have a let-down. That’s because the oxytocin not only makes the muscles around the alveoli squeeze, but also makes the uterus contract and return to its non-pregnant size over the next few weeks. This is one of the many benefits of breastfeeding.

2) Factors that can stop the let-down

Let-downs can be weaker or less frequent with:

C) The feel of a let-down

Many mothers feel the let-down. The breasts can:

  • Feel tight.
  • Feel squeezed.
  • Burn.
  • Hurt.

The sensation is usually gone in less than a minute. As with cramps, the pain starts, grows, and then gradually disappears. Mothers with a larger milk supply are more likely to have pain with the let-down.

Most mothers only feel the first let-down and not later ones. The feeling of the let-down and let-down pain disappear as the baby grows and in time, the mother may not feel the let-down at all (Ramsay 2004).

Mothers are often thirsty with the let-down in the first few months after delivery. Rarely, some mothers might feel sudden arousal, extreme sadness, or headaches (dysphoric milk ejection reflex) with the let-down.

Some normal mothers never feel their let-down. There is no need to worry about this. These mothers only need to ensure that their babies are growing well as not feeling the let-down can also happen in mothers whose milk supply is low.

References

Geddes DT. Inside the lactating breast: the latest anatomy research. J Midwifery Womens Health.  2007 Nov-Dec;52(6):556-63
 
Matthiesen AS, Ransjo-Arvidson AB, Nissen E, et al. Postpartum maternal oxytocin release by newborns: Effects of hand massage and suckling. Birth 2001; 28(1), 13–19
 
Ramsay DT, Kent JC, Owens RA, et al. Ultrasound imaging of milk ejection in the breast of lactating women. Pediatrics 2004;113(2), 361–367