How Much Breast Milk Does a Lactating Woman Make?

Patient Presentation
A 4-month-old male came to clinic for his health supervision visit. His mother had no concerns and he was rolling over, smiling, transferring toys, putting them in his mouth and saying many vowel sounds. His mother only noted that he seemed to be more active and at times eating more. “It seems like some days even now I’m just breastfeeding him. He can get really hungry at times,” she said.

The pertinent physical exam showed a smiley infant with a weight of 50%, head circumference of 25% and length of 75%.
His examination was normal and he still had a head lag when pulled from lying to sitting.

The diagnosis of a healthy infant was made. “You have a healthy son. He’s still not ready for solid foods though so you just need to keep breastfeeding him. Are you remembering to have a snack yourself and drink each time he eats?” the pediatrician asked. “Sometimes it seems like feeding him, and me eating, is all I do. I’m always so thirsty and hungry,” the mother replied. “We’ll that sounds pretty normal. You need to eat more to feed him and drink too. Try to keep some healthy snacks ready to go, so you can get one and something to drink before you sit down to feed him. No hot drinks though. You don’t want him to bump you and get burned,” the pediatrician reminded the mother.

After leaving the room, the third year medical student asked, “How much milk does a mother make? It doesn’t seem like it would be enough to make her so hungry?” The pediatrician smiled, “It’s more than you think. If you remember back to your basic science nutrition course, she needs to eat more now than when she was pregnant. It’s about 500 calories a day. That’s about 25-30% more than someone who isn’t pregnant. Then she has to drink all the extra fluid to make the breast milk. I’ve never figured it out but it is gallons she makes over a year; it’s just made fresh a few ounces at a time.”

Each person needs to eat the right about of healthy foods to maintain a healthy body.
This varies based on gender, age, activity, healthy problems, or health status.

Healthy women who are moderately active and not pregnant or lactating need about 1800-2000 calories/day. Pregnant women are advised to keep the calories the same in the first trimester (about 1800 calories/day), increase ~200-300 (about 2200 calories/day)in the second trimester, and then increase ~300-400 in third trimester (about 2400 calories/day). The increase in calories should be met by a normally balanced and varied diet. When pregnant or breastfeeding women should eat a diet rich in protein, omega-3 polyunsaturated fats, calcium, iron and folic acid, along with all the necessary vitamins, minerals, and fiber.

Breastfeeding is recommended throughout at least the first year of life by the American Academy of Pediatrics and up to 24 months by the World Health Organization. Complimentary foods are not recommended until after 6 months of age if the infant is developmentally ready.

Learning Point
Healthy, well-nourished, lactating women are advised to increase their calories by 450-500/day. That is a lot of calories which is turned into ~70 gallons or ~250 liters of breast milk/year. Women who are under- or malnourished will have additional needs and should be advised by their health care providers.

The table below shows the various calculations:

450 extra calories/day 500 extracalories/day
Calories/year 164,250 182,500
Breast milk Produced in Ounces (mLiters)/day 22.5 (0.625) 25 (0.725)
Breast milk Produced in Gallons (Liters)/year 64.1 (238.1) 71.3 (264.6)
Breast milk Produced by Weight in Pounds (Kilograms)/year 535.4 (238.1) 594.9 (264.6)

If a woman did not have access to adequate nutrition, the number of calories/year expended to support the breastfeeding would be the equivalent of losing ~50 pounds.

Questions for Further Discussion
1. What are the breastfeeding rates in your practice, region or country?
2. What factors help initiate breastfeeding after birth?
3. What guidance can help support breastfeeding ?
4. What are the maternal advantages of breastfeeding?
5. What are the infant advantages of breastfeeding?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Pregnancy and Nutrition and Breastfeeding.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

CDC. Diet considerations for breastfeeding mothers. Centers for Disease Control and Prevention. Published February 10, 2020. Accessed February 18, 2020.

Guideline: counselling of women to improve breastfeeding practices. Geneva: World Health Organization; 2018.

American Academy of Pediatrics. Breastfeeding and the Use of Human Milk. Accessed February 18, 2020.

Eating right during pregnancy: MedlinePlus Medical Encyclopedia. Accessed February 18, 2020.

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa