Key takeaways: Moderate exercise doesn’t reduce milk supply or harm your baby’s growth, according to research. Start gradually when your provider says it’s okay, feed or pump before exercising for comfort, wear a supportive bra, and drink to thirst. Most babies don’t mind milk after exercise.
Exercise can boost your mood, energy, and fitness after birth. Breastfeeding parents can exercise safely.
Does Exercise Affect Milk Supply?
A randomized trial by Dewey and colleagues published in 1994 found that regular aerobic exercise didn’t affect milk volume or composition or babies’ growth. Very intense exercise with rapid weight loss or under-eating may be a different story, so eat enough.
Lactic Acid and Taste
A small 1992 study found that lactic acid in milk rose after maximal (very intense) exercise and some babies seemed less accepting of milk right afterward. Later research found moderate exercise doesn’t meaningfully change lactic acid. If your baby seems fussy after a hard workout, feed before exercise or wait a bit after.
When to Start
ACOG says many people can begin or resume exercise soon after an uncomplicated birth, gradually, when they feel ready. After a cesarean or complicated birth, ask your provider. Start with walking and pelvic floor exercises.
Tips for Comfort
- Feed or pump before exercising so breasts aren’t full.
- Wear a supportive sports bra that doesn’t compress the breasts too tightly.
- Drink to thirst and eat enough.
- Shower or rinse if your baby dislikes the taste of sweat.
Weight Loss
Gradual weight loss of about 1 pound a week is generally considered safe once breastfeeding is established. Rapid weight loss and crash dieting may affect supply.
Pelvic Floor and Core
Your pelvic floor and abdominal muscles need time to recover. Consider a pelvic floor physical therapist if you have leaking, heaviness, pain, or abdominal separation.
Mental Health Benefits
Exercise can help with postpartum mood. It’s not a replacement for treatment if you have depression or anxiety.
Stop and call your provider if you have: heavy bleeding, chest pain, dizziness, calf pain or swelling, or pelvic pain during or after exercise.
The Bottom Line
Moderate exercise is safe and healthy while breastfeeding. Start slowly, eat enough, feed before workouts, and listen to your body.
Want more support for your baby’s first year? My book, From First Breath to First Birthday, is available on Amazon.
Sources
- Dewey KG, Lovelady CA, Nommsen-Rivers LA, McCrory MA, Lönnerdal B. A randomized study of the effects of aerobic exercise by lactating women on breast-milk volume and composition. N Engl J Med. 1994;330(7):449-453.
- American College of Obstetricians and Gynecologists. Committee Opinion No. 804: Physical activity and exercise during pregnancy and the postpartum period. Obstet Gynecol. 2020;135(4):e178-e188.
- Wallace JP, Inbar G, Ernsthausen K. Infant acceptance of postexercise breast milk. Pediatrics. 1992;89(6 Pt 2):1245-1247.
This article is for general education and is not a substitute for individualized medical advice. Always talk with your baby’s health care provider or your own provider about your specific situation. If you think your baby or you may have a medical emergency, call 911.
