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Breastfeeding? Why you should keep (or start!) exercising

Written by Dr. Karen Fleming

I’m always happy when my patients who have just had a baby ask me about exercise. Many have heard anecdotally that they shouldn’t exercise and breastfeed. One new mom was told by a friend “exercise will make your breast milk sour.” Not true!

Exercise plays an important role in our lives and helps to improve fitness and reduce the risk of many chronic diseases like diabetes, heart disease and cancer. With planning, new moms can fit exercise in with the demands of a new baby. Walking is an excellent form of exercise which can include baby in the stroller as well as enjoying the benefits afforded by group support. Many choose to walk with friends or join a walking mother’s group in their area. Moms may enjoy time walking with their partner and children to improve the health of the entire family. Public health units and local Community Health Centres can also help women connect with exercise options in their area.

That said, many breastfeeding mothers worry about whether exercise can affect breastfeeding, milk supply, and baby’s growth.

Exercise and the new mother 

Exercise improves wellbeing in so many ways. Exercise is good medicine across the lifespan and an opportunity to role model healthy lifestyle for the entire family while improving your health. Exercise improves heart health, fitness, energy, bone strength, facilitates return to pre-pregnancy weight and reduces rates of postpartum depression and anxiety.

Exercise and breast milk supply

Exercise at high intensity does lead to accumulations of lactic acid as most of us have experienced. Lactic acid does increase in breast milk following intense exercise however mild to moderate exercise in keeping with our current guidelines does not increase lactic acid significantly. Even if you are an elite athlete, there is no evidence increased lactic acid levels in breast milk is a concern for your baby. The bottom line is that quality of breast milk is not impacted and moderate exercise does not impact your baby’s growth.

Tips for success

  1. Breastfeed prior to exercising (empty breasts are more comfortable)
  2. Wear a supportive bra for increased comfort especially with higher impact exercise
  3. Focus on hydration and drink water. Remember, you’re hydrating for two
  4. Look for options to exercise together as a family or with a group for support
  5. Talk to your physician, midwife or breastfeeding clinic for further advice

For more info, visit the Society of Obstetricians and Gynaecologists of Canada website.

About the author

Dr. Karen Fleming

Dr. Karen Fleming is a family physician with a special interest and expertise in pregnancy and birth.

She is the Division Lead for Family Medicine Obstetrics at Sunnybrook. She is also the Chief of Sunnybrook's Department of Family and Community Medicine.

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