Mothers can express to see how much milk they are making.
Instead of breastfeeding, mothers express and measure the amounts. They should have milk ready for the baby’s replacement feed while they are expressing. Before proceeding, mothers must ensure that the baby will accept such feeds.
Some mothers cannot express well for a variety of reasons and will leave milk in the breast, causing them to underestimate how much milk they are making (Meier 2016).
While expressing can assess how much milk a mother makes, it does not show how much milk the baby is taking in.
Here, in order of preference, are three ways to use expression to estimate milk supply:
1) Hourly expressing for four hours
Several studies show that mothers can express with a breast pump to assess their milk supply (Kent 2018; Lai 2010; Roznowski 2019; Roznowski 2020).
This is done as follows:
- Starting after the baby has breastfed, mothers pump every hour for four hours:
- Using a double electric pump.
- With the suction strength set to the maximum comfortable level.
- Until the milk flow is reduced to infrequent drips (about 10 minutes).
- Mothers keep track of how much they pump.
- The baby is given a replacement feed when hungry.
- Breastfeeding resumes after the fourth pumping and when the baby is hungry.
The amount of milk obtained at the third and fourth pumping is roughly the amount made each hour. These two amounts can be added together and divided by 2 to average the amount. This amount is multiplied by 24 to see how much milk is made in one day.
For example, a mother may pump 17 millilitres at the third pumping and 23 ml at the fourth. The average of the two is 20 ml. This amount is multiplied by 24 to see how much milk is made in one day. In this example, the mother makes about 480 ml (16 oz) each day.
The first two pumps are necessary to empty the breast.
2) Occasional expressing
Mothers may express at the occasional feed, done several times and at different times of the day, since the amount of milk in the breast can vary. This will give a very rough idea of how much milk may be present.
3) Extended expression
Mothers may choose to only express and not breastfeed for 12 to 24 hours. It is more accurate than occasional expressing but has more risks.
Mothers who do not express well may have over-full breasts at the end of this period. They should quickly stop expressing and resume breastfeeding.
The longer the baby is away from the breast, the higher the risk of the baby being reluctant to resume breastfeeding.