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Exercise During Pregnancy May Boost the Benefits of Breastfeeding

Pregnant woman walking in remote area
Getting some steps in during pregnancy can have far-reaching benefits.

 Erik Isakson / Getty Images

Key Takeaways

  • A recent study suggests exercising while pregnant can increase a compound that's been linked to health benefits for infants.
  • In addition to boosting breastfeeding benefits, exercising can help a woman ease pregnancy issues, get ready for delivery, and lighten postpartum anxiety.
  • Not all exercise is recommended for pregnant women, especially if you have issues like gestational diabetes, so talk to your doctor before you start.

Even moderate exercise during pregnancy may increase a compound in breast milk that's been linked to lower health risks in babies, including diabetes, heart disease, and obesity.

Published in Nature Metabolism, the study involved 150 pregnant and postpartum women who wore activity trackers during pregnancy and afterward. Those who had more steps per day showed higher level of a compound known as 3SL, or oligosaccharide 3-sialyllactose, found exclusively in breast milk. The compound has been shown to confer health advantages even later in life.

To confirm that the level of 3SL was from breast milk and not an inherited trait, researchers also gave baby mice born from sedentary mothers milk produced by mice that were active through pregnancy. The health benefits from the fit mice transferred to the babies, researchers noted.

Especially notable, exercise intensity didn't seem to play a role for either the humans or mice, says lead researcher Kristin Stanford, PhD, at The Ohio State Wexner Medical Center. Even moderate-intensity activity like taking a brisk walk was enough to boost the 3SL level, she says. And it had that effect regardless of body composition of the participants, she adds.

Kristin Stanford, PhD

It didn't really matter what your starting body mass index was or your starting body weight, as long as you were moving, we saw these effects.

— Kristin Stanford, PhD

Researchers didn't suggest a mechanism in terms of why exercise would have this effect, so Stanford noted that's a direction for future research, along with whether 3SL can be isolated as a compound to be added to infant formula or supplements in the future.

Benefits of Breastfeeding

The transfer of 3SL, as well as other beneficial compounds that can only be passed through breast milk, is one of the main reasons that public health agencies like the World Health Organization (WHO) have long been promoting breastfeeding for at least the first six months of a baby's life.

The WHO emphasizes that breast milk is the ideal food for infants, and contains antibodies that help protect against many common childhood illnesses, in addition to lowering health risks overall. Also, women who breastfeed have a reduced risk of breast and ovarian cancers, the WHO notes.

Additional Benefits of Exercise

Beyond the potential effects on 3SL, exercising during pregnancy can bring a range of other benefits, according to nurse and lactation consultant Deedee Franke, RN, of Mercy Medical Center in Baltimore.

She says exercise during pregnancy has been shown to:

  • Reduce backaches
  • Alleviate pregnancy-related constipation
  • Reduce bloating and swelling
  • Improve mood
  • Promote good muscle tone
  • Increase strength
  • Improve sleep

Exercise can also make both pregnancy and postpartum time easier, adds Samantha Radford, PhD, who owns a parenting consulting service, Evidence-Based Mommy. Radford suggests prenatal yoga as a way to increase flexibility and strength while emphasizing a mind-body connection.

Samantha Radford, PhD

Gentle exercise during pregnancy keeps a woman's body strong and better able to bear the physical stressors of pregnancy, as well as get ready for labor and delivery.

— Samantha Radford, PhD

"Gentle postpartum exercise, after clearance from an OB, can help a woman lose baby weight and improve postpartum anxiety and depression," she adds. Research published in Birth found that physical activity during and after pregnancy—even a low-intensity type like walking with a stroller—was linked to a lower likelihood of depressive symptoms for new mothers.

Walking is usually considered the safest prenatal exercise option, but some women may struggle with going longer distances in their third trimester, if swelling feet and abdominal pressure become an issue. Consider finding exercise classes and fitness choices specifically geared toward pregnancy, such as prenatal yoga, swimming or water aerobics, and low-impact options like Barre or modified Pilates.

What This Means For You

Although this study and others highlight the potential benefits of exercising while pregnant, keep in mind that not every activity is well suited for pregnancy. It's important to check with your OB/GYN and talk about exercise that's appropriate, especially if you have other health concerns, such as gestational diabetes or cardiovascular issues.

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  1. Harris J, Pinckard K, Wright K et al. Exercise-induced 3′-sialyllactose in breast milk is a critical mediator to improve metabolic health and cardiac function in mouse offspringNat Metab. 2020. doi:10.1038/s42255-020-0223-8

  2. WHO. Exclusive breastfeeding for six months best for babies everywhere. Updated January 15, 2011.

  3. WHO. Continued breastfeeding for healthy growth and development of children. Updated June 2017.

  4. ACOG. Exercise during pregnancy. Updated July 2019.

  5. Poyatos‐León, R, García‐Hermoso, A, Sanabria‐Martínez, G, Álvarez‐Bueno, C, Cavero‐Redondo, I, Martínez‐Vizcaíno, V. Effects of exercise‐based interventions on postpartum depression: A meta‐analysis of randomized controlled trials. Birth. 2017;44(3):200-208. doi:10.1111/birt.12294

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