How Much Milk Should You Expect to Pump?

Do you ever have parents second-guess their milk production after pumping? Do they compare it with the volume of milk their friend or neighbor pumps? Do they compare it with the milk they pumped for a previous baby? Before they start to worry, they first need to know how much pumped milk is average. Many mothers discover—to their surprise—that when they compare their own pumping experience with the norm, they’re doing just fine. Take a deep breath and read on.

Expect Less Milk in the Early Weeks

If the first month of exclusive breastfeeding is going well, milk production dramatically increases from about one ounce (30 mL) on Day 1 to a peak of about 25 ounces (750 mL) per baby around Day 40. Draining breasts well and often naturally boosts milk during these early weeks. But at first, while milk production is ramping up, expect to pump less milk than they will later. If they pumped more milk for a previous child, they may be thinking back to a time when their milk production was already at its peak rather than during the early weeks while it was still building.

Practice Makes Perfect

What should the family expect when they begin pumping? First know it takes time and practice to train the body to respond to their pump like it does to their baby. At first they will probably be able to pump small amounts, and this will gradually increase as time goes on.Don’t assume (as many do) that what they pump is a gauge of their milk production. That is rarely the case, especially the first few times they pump. It takes time to become proficient at pumping.  Even with good milk production and a good-quality pump, some parents find pumping tricky at first.

Factors That Affect Milk Yield

After the parent has had some practice using your pump and it’s working well, the following factors can affect milk yield:

• The baby’s age
• Whether or not they’re exclusively breastfeeding
• Time elapsed since last breastfeeding or pumping
• Time of day
• Their emotional state
• Their breast storage capacity
• Their pump quality and fit

Read on for the details about each of these factors.

The baby’s age. How much milk a baby consumes per feeding varies by age and—until one month or so—by weight. Because newborns’ stomachs are so small, during the first week most full-term babies take no more than 1 to 2 ounces (30 to 60 mL) at feedings.  After about four to five weeks, babies reach their peak feeding volume of about 3 to 4 ounces (90 to 120 mL) and peak daily milk intake of about 25 ounces per day (750 mL).

Until the baby starts eating solid foods (recommended at around six months), her feeding volume and daily milk intake will not vary by much. Although a baby gets bigger and heavier between one and six months of age, her rate of growth slows down during that time, so the amount of milk she needs stays about the same. (This is not true for formula-fed babies, who we tend to over feed so they consume much more as they grow and are also at greater risk for obesity.) When the baby starts eating solid foods, her need for milk will gradually decrease as solids take the milk’s place in her diet.

Exclusively breastfeeding? An exclusively breastfeeding baby receives only mother’s milk (no other liquids or solids) primarily at the breast and is gaining weight well. A mother giving formula regularly will express less milk than an exclusively breastfeeding mother, because her milk production will be lower. If the family is giving formula and the baby is between one and six months old, they can calculate how much milk they should expect to pump at a session by determining what percentage of the baby’s total daily intake is at the breast.

To do this, subtract from 25 ounces (750 mL) the amount of formula the baby receives each day. For example, if the family is giving 15 ounces (450 mL) of formula each day, this is half of 30 ounces (900 mL), so they should expect to pump about half of what an exclusively breastfeeding mother would pump.

Time elapsed since the last milk removal. On average, after an exclusively breastfeeding mother has practiced with her pump and it’s working well for her, she can expect to pump:

• About half a feeding if she is pumping between regular feedings (after about one month, this would be about 1.5 to 2 ounces (45-60 mL)
• A full feeding if she is pumping for a missed feeding (after one month, this would be about 3 to 4 ounces (90-120 mL)

Time of day. Most women pump more milk in the morning than later in the day. That’s because milk production varies over the course of the day. To get the milk they need, many babies respond to this by simply breastfeeding more often when milk production is slower, usually in the afternoon and evening. A good time to pump milk to store is usually thirty to sixty minutes after the first morning nursing.

Most mothers will pump more milk then than at other times. If the parent is an exception to this rule of thumb, pump when they get the best results. No matter when they pump, they can pump on one side while nursing on the other to take advantage of the baby-induced let-down. They can offer the other breast to the baby even after they pump and baby will get more milk.

Emotional state. If the parent feels upset, stressed, or angry when they sit down to pump, this releases adrenaline into the bloodstream, which inhibits milk flow. If they are feeling negative and aren’t pumping as much milk as usual, take a break and pump later, when they are feeling calmer and more relaxed.

Breast storage capacity. This is the maximum amount of milk available in their breasts during the time of day when their breasts are at their fullest. Storage capacity is based on the amount of room in milk-making glands, not breast size. It varies among mothers and in the same mother from baby to baby. As one article describes, the largest pumping can provide a clue to whether the storage capacity is large, average or small. Mothers with a larger storage capacity usually pump more milk at a session than mothers with a smaller storage capacity.

If they are exclusively breastfeeding and pumping for a missed breastfeeding, a milk yield (from both breasts) of much more than about 4 ounces (120 mL) may indicate a larger-than-average storage capacity. On the other hand, if they never pump more than 3 ounces (90 mL), even when it has been many hours since your last milk removal, their storage capacity may be smaller-than-average.

What matters to the baby is not how much she gets at each feeding, but how much milk she receives over a 24-hour day. Breast storage capacity explains many of the differences in breastfeeding patterns and pump yields that are common among mothers.7

Pump quality and fit. For most mothers, automatic double pumps that generate 40 to 60 suction-and-release cycles per minute are most effective at expressing milk.

Getting a good pump fit is important, because your fit affects comfort and milk flow. Pump fit is not about breast size; it’s about nipple size. It refers to how well nipples fit into the pump opening or “nipple tunnel” that the nipple is pulled into during pumping. If the nipple tunnel squeezes the nipple during pumping, this can reduce milk flow and they will pump less milk. However, some families find they need a much smaller size than anticipated. Keeping an open mind about sizing is very important. Also, either a too-large or too-small nipple tunnel can cause discomfort during pumping. Small-breasted women can have large nipples and large-breasted women can have small nipples. Also, because few women are completely symmetrical, they may need one size nipple tunnel for one breast and another size for the other.

You know you have a good pump fit for a parent when they are comfortable and are getting plenty of milk . You’ll know you need to try a different size nipple tunnel if you feel discomfort during pumping even when the pump suction is near its lowest setting.

What About Pump Suction?

Mothers often assume that stronger pump suction yields more milk, but this is not true. Too-strong suction causes discomfort, which can inhibit milk flow. The best suction setting is the highest that’s truly comfortable and no higher. This ideal setting will vary from mother to mother and may be anywhere on the pump’s control dial. Some mothers actually pump the most milk near the minimum setting.

Could the pump be malfunctioning? It’s normal for a pump’s suction to feel less strong over time as its user adjusts to its feel. Many pump users ask how often certain pump parts should be replaced. A rule of thumb is that the parts that directly affect the pump’s suction should be replaced every six months or so. In some cases, extra membranes and valves are provided with new pumps. Extras can usually be ordered online or bought at large baby stores. If there is a hole in the membrane or the white valve stays open even when the pump is not in use, replace these pump parts sooner.  Other pump parts are unlikely to affect  your milk yields.

Hands-on Pumping

Hands-on pumping is one evidence-based strategy to increase milk yield while pumping.  Click here for a post describing this effective technique.

Worries are a normal part of new motherhood, but parents can make milk expression a much more pleasant experience by learning what to expect. For many mothers, pumping is a key aspect of meeting their breastfeeding goals.  A little knowledge can go a long way in making this goal a reality.

If you work with breast/chestfeeding families and who is passionate about lactation support OR a  and you want to turn your passion for nursing into professional practice, check out LactaLearning.com and consider following us on social media!

Instagram @lacta.learning

Facebook LactaLearning

References

Davanzo & Baldassarre, 2024 Infant Growth Spurts in the Context of Perceived Insufficient Milk Supply. https://pubmed.ncbi.nlm.nih.gov/39519490/

Kent, J. C. (2007). How breastfeeding works. J Midwifery Womens Health, 52(6), 564-570.

Mohrbacher, N. (2011). The magic number and long-term milk production.Clinical Lactation, 2(1), 15-18.

Kent, J. C., Mitoulas, L. R., Cregan, M. D., Ramsay, D. T., Doherty, D. A., & Hartmann, P. E. (2006). Volume and frequency of breastfeedings and fat content of breast milk throughout the day. Pediatrics, 117(3), e387-395.