Describing before-feed and after-feed weights 

What are before-feed and after-feed weights?

Sometimes it is important to know how much milk a baby is taking in, especially if the mother is concerned about a low milk supply or the baby is premature or slow-growing. One way to do this is to weigh the baby before and after a breastfeed and calculate the difference. The two figures are called the before-feed and after-feed weights. Mothers who need to do this calculation should work with their health-care providers. They will need a sensitive baby-weighing scale and will need to weigh the baby before the feed and after feeding. Changing the baby’s diaper or clothing during the feed or using a different pad under the baby for each weighing will affect the results.

A) Describing before-and-after weights

Mothers who have a full milk supply, are exclusively breastfeeding, and have a baby who is growing well do not need to know how much milk they make. Their baby’s normal growth shows they have enough milk.

Assessing the amount of milk a baby takes in may be important for babies whose mothers appear to have a low milk supply or who are premature or growing poorly.

One way to do it is to weigh the baby before and after a breastfeed and calculate the difference between the two measurements, the before-feed and after-feed weights (before-and-after weights). This allows mothers and health-care providers to see how much weight the baby gained by breastfeeding. In other words, how much milk the baby took in at the feed (Arthur 1987; Meier 1990).

Mothers are encouraged to work with their health-care providers when considering before-and-after weights, since they can be a little confusing.

B) Reasons for using before-and-after weights

There are three reasons for using before-and-after weights.

1) To see how much milk a mother is making

Mothers with a low milk supply may benefit from knowing how much milk they are making. If the baby is breastfeeding normally and is healthy, before-and-after weights will show how much milk a baby takes in from the breast and this would reflect how much milk a mother can make.

Mothers may also wish to use a scale to measure the effect of herbs or medication used to increase milk supply.

2) To see how much milk a premature baby is taking from the breast

Premature babies may have major breastfeeding challenges and are often too sleepy and weak to give clear hunger signs. Before-and-after weights can help mothers and health care providers see how much milk a premature baby takes from the breast, if a nipple shield is helping, and how the baby’s skills are improving.

3) To see how much milk a slow-growing baby is taking from the breast

Some babies do not grow well. Before-and-after weights can help mothers and health-care providers see if the cause is a low milk supply or illness.

C) Planning for before-and-after weights

If it is appropriate to do before-and-after weights, mothers need to:

  1. Get a sensitive breastfeeding scale.
  2. Decide how many feeds they need to measure.
  3. Understand how to calculate the amounts of milk.
  4. Continue to supplement the baby with milk, if needed.

D) The breastfeeding scale

A breastfeeding scale is much more accurate than a bathroom scale or even some baby-weighing scales. A typical baby-weighing scale measures in 10-gram (1/3-ounce) increments. For better accuracy, mothers should consider using a breastfeeding scale as these can measure 2-gm (0.1-oz) increments. 

There are several breastfeeding scales on the market. Mothers rarely need to buy a scale; most mothers who need one will rent it for a week.

E) How to do before-and-after weights

Here are the steps for before-and-after weights:

  1. Start once the baby shows hunger signs.
  2. Weigh the baby.
  3. Write down the baby’s before-feed weight.
  4. Breastfeed the baby on the first breast.
  5. If the baby is hungry after the first side, breastfeed the baby on the second breast.
  6. Weigh the baby.
  7. Write down the baby’s after-feed weight.
  8. Supplement the baby with milk if the baby is still hungry.
  9. Ensure that the baby is happy when fed and held.

Changing anything between weighings can affect the numbers and should be avoided. This includes:

  • Changing the baby’s diaper.
  • Adding or removing clothes.
  • Using a different pad under the baby for each weighing.
  • Using a different scale for the before and the after weight, which can happen if the baby is in hospital.

Once the baby is settled, calculate the milk intake by subtracting the before weight from the after weight as in this example:

After weight:       3,878 gm

Before weight:  - 3,818 gm

Difference:              60 gm

The baby gained 60 gm. This is the weight of 60 millilitres of milk. There are about 30 gm in a US fluid ounce, so the baby took in 2 oz.

F) Duration of before-and-after weights

When before-and-after feed weights are used to see how much milk a mother is making or deciding if a baby is sick or underfed, it is best to see how much milk a baby takes in over 24 hours and repeating this for a second day. The days can be separated, for example on a Monday and Thursday.

When used to see how well premature babies are breastfeeding, they can be done for a few feeds here and there.

G) Drawbacks of before-and-after weights

The drawbacks are:

  • The cost of renting the breastfeeding scale.
  • The time and effort involved.
  • The information is limited to the present situation and does not indicate how:
    • The milk supply will change.
    • The baby will breastfeed in the future.
  • The chance of making a mistake in weighing or calculating the weights.
  • Continued reliance on the scale when the baby may be able to show clear signs of hunger and being full, making the scale unnecessary.


Arthur PG, Hartmann PE, Smith M. Measurement of the milk intake of breast-fed infants. J. Pediatr. Gastroenterol. Nutr. 1987, 6, 758–76
Meier PP, Lysakowski TY, Engstrom JL, et al. The accuracy of test weighing for preterm infants. J Pediatr Gastroenterol Nutr. 1990 Jan;10(1):62-5