A new study led by researchers at The Ohio State University Wexner Medical Center and College of Medicine finds even moderate exercise during pregnancy increases a compound in breast milk that reduces a baby’s lifelong risks of serious health issues such as diabetes, obesity and heart disease.
Findings from the study published online today in the journal Nature Metabolism.
“We’ve done studies in the past that have shown that maternal exercise improves the health of offspring, but in this study, we wanted to begin to answer the question of why,” said Kristin Stanford, a researcher at The Ohio State Wexner Medical Center’s Diabetes and Metabolism Research Center and lead author of the study.
“Because there is evidence that breast milk plays a major role, we wanted to isolate the effects of breast milk on offspring health.”
To do that, Stanford and her team – including researchers at the University of California, San Diego, Arkansas Children’s Nutrition Center, and the Joslin Diabetes Center – studied mice born from sedentary mothers and fed them milk from mothers who were active throughout pregnancy.
They found that the health benefits from fit moms transferred to the pups, proving that they were, in fact, passed through breast milk and not simply inherited genetic traits.
Researchers also followed about 150 pregnant and postpartum women using activity trackers and found that those who had more steps per day had an increased amount of a compound known as 3SL in their breast milk, which they believe is responsible for these health benefits.
“The increase in 3SL were not necessarily related to exercise intensity, so even moderate exercise like a daily walk is enough to reap the benefits,” said Stanford, an associate professor of physiology and cell biology at Ohio State’s Dorothy M. Davis Heart and Lung Research Institute. “Exercise is also great for your overall health during and after pregnancy, so anything you can do to get moving is going to benefit both you and your baby.”
Because many women are unable to breastfeed or experience complications that require bed rest, researchers are examining if they can isolate this beneficial compound found in the breast milk of active moms and add it to infant formula.
“This human milk oligosaccharide had a significant impact on offspring healthy. Being able to add this into formula could provide benefits for babies when women aren’t able to breastfeed,” Stanford said.
Exercise contributes significantly to maternal and fetal wellbeing during pregnancy. Traditionally women were advised to refrain from exercise during pregnancy, but newer evidence has shown this to be false.
Theoretically, there were concerns about premature labor and the risks of delivering smaller infants to women who exercised during pregnancy. A recent meta-analysis that included over 2000 women showed that aerobic exercise and strength/toning exercise of moderate-intensity that was performed 3-4 days per week throughout the pregnancy was not associated with an increased risk for preterm births or low birth weight infants for normal-weight women with singleton, uncomplicated pregnancies.
Despite recommendations from physicians to begin or maintain an exercise program during pregnancy, only about 40% of the patients exercise. A pregnant patient can be easily motivated to improve her health as well as the health of her unborn child, but these recommendations need to be practical, with persistent follow-up by the physician. Physical exercise can help with some common discomforts and even prepare one’s body for labor and delivery.
A sedentary lifestyle during pregnancy is associated with significant health risk of deep venous thrombosis which threatens the lives of the infant and mother. A sedentary lifestyle can lead to obesity or at least significantly contribute to persistent obesity.
Obesity is of epidemic proportions in the U.S., and obesity during pregnancy carries elevated risks for major complications. Patients with obesity are also more likely to suffer spontaneous abortions. Also, they have a higher risk of neural tube defects which include cleft palate, spina bifida, and hydrocephalus.
Obesity also puts the pregnant patient at risk for gestational diabetes, preeclampsia, sleep apnea, macrosomia, preterm birth, and even stillbirth. The higher the women’s BMI, the greater the risk of stillbirth. Exercise is safe in these women and is encouraged. Even the previously sedentary patient is encouraged to start an exercise program early in pregnancy. It is also considered safe in some high-risk pregnancies such as those with chronic hypertension and gestational diabetes. Contraindications will be discussed later.
Exercise in pregnancy has been shown to decrease macrosomia, gestational diabetes, preeclampsia, cesarean delivery, low back pain, pelvic girdle pain, and urinary incontinence. In counseling a pregnant patient, sometimes it is not so much about recommending to her that she needs to exercise but rather giving her specific recommendations such as which exercise is safe and when she should begin?
If a patient participates in regular exercises before pregnancy, then it is acceptable to continue this same regimen during pregnancy. Sometimes the intensity may need to be decreased, or if the activity involves a contact sport then adapting to a different activity would be wiser for overall safety. Aerobic exercise is considered the most beneficial.
This is sometimes referred to as cardio exercise which involves the heart pumping oxygenated blood to the working muscles. It uses large muscle groups (legs/ arms) repetitively for a sustained amount of time.
Ideally, 150 min per week is performed. This can be broken into smaller sessions- for example, 30 minutes per day for five days each week. If one is beginning an exercise program, then one can begin with as little as 5 minutes a day and then add 5-10 minutes each week.
Common examples of cardiovascular exercise are walking, cycling, stair steppers, ellipticals, swimming, aerobic dance, and yoga. One should be exercising vigorously enough to elevate one’s heart rate to approximately 110-120 beats per minute. (This varies with age, but the average pregnant woman is between 18-35 years of age.)
A practical way to monitor one’s exercise intensity is the “talk test.” If the individual can converse while exercising, she usually will not be overexerting.
Overexertion can lead to complications in pregnancy and should be avoided. Walking is easy, requires no skill or cost, and can be done indoors or outdoors. One should pay close attention to adequate hydration and temperature control of the environment while pregnant especially if the patient is new to exercise and just beginning a regimen.
A pregnant woman should avoid overheating, and a mall or an indoor track or treadmill can provide a safe and protected environment for her while exercising. Drinking water before and throughout exercise can prevent overheating and dehydration.
Cycling is best if it is done on a stationary bike since falling is more likely to occur with a regular bike and could injure the pregnant patient and her unborn fetus.
Cycling can be more comfortable than walking, which can cause strain in the pelvis. Swimming is an excellent aerobic exercise and is ideal if one suffers from joint pain or other discomforts of pregnancy.
The water provides buoyancy and a weightless environment for one to work on all the major muscle groups. Yoga and Pilates are excellent stretching and strengthening exercises that can also improve mental health and reduce pain.
These are just examples of potential options. There are some forms of exercise that one should avoid during pregnancy. Any contact sport (basketball/ soccer) or sport that can cause significant injury (horseback riding/ hockey), or altitude changes (skiing/ skydiving/ scuba diving) should be avoided during pregnancy.
Issues of Concern
Women should monitor themselves during exercise even if they have a history of performing intense exercises before pregnancy. Maintaining hydration, preventing exposure to heat or humidity, and avoiding hypoglycemia is important during this process.
Warning signs or symptoms of a potential problem include regular painful contractions, vaginal bleeding, dyspnea on exertion, dizziness, headache, chest pain or calf pain. If these symptoms should occur, the pregnant patient should stop exercising and consult with her physician immediately.
Overexertion and strenuous aerobic exercise are not recommended and could compromise the well-being of the infant due to the diversion of blood flow to the vital maternal organs away from the fetal-placental unit. Heavy weightlifting and long-distance running are also discouraged for the same reasons. The pregnant patient needs to avoid the supine position since this will put pressure on the vena cava and compromise blood return to the heart thus potentially compromising the blood flow to the fetus.
Absolute contraindications to exercise include diagnosis of placenta previa, incompetent cervix, second or third trimester bleeding, preterm premature rupture of membranes, preterm labor, significant heart or lung disease, preeclampsia or severe anemia. Patients with such high-risk diagnosis are encouraged to ambulate rather than an exercise in order to minimize their risk of thromboembolism. 
Women should begin an exercise program to improve their pregnancy outcome and the health of the infant. Weight loss may occur as a result of a patient who previously had a sedentary lifestyle but has now developed an active one, but it is not the goal during pregnancy. It is a possible side effect. Proper exercise during pregnancy will help with weight loss after delivery.
Exercise is considered safe and beneficial in most pregnancies. It improves the health of the mother and the well-being of the infant. Continued exercise after delivery is recommended to diminish the pregnancy weight gain and overall health of the mother. The important thing is that any type of exercise is good during pregnancy.
Some women may want to join a gym or have an exercise trainer. However, one can simply walk for 45-60 minutes every day and that alone is as good as any exercise. Swimming is another great exercise that eases the pressure off the lower back. However, one should not get carried away with exercise; extreme physical activity is not recommended as this can lead to a fall and jeopardize the health of the fetus.
As the pregnancy advances, the amount of exercise one can do will lessen but one should continue to walk. To avoid the leg swelling during exercise, wear compression stockings. Exercise has repercussions way beyond just pregnancy- regular exercise can relieve stress, allows you to enjoy nature, lose weight, lower your blood pressure and cholesterol, and more important enhances self-confidence. (Level V)
Enhancing Healthcare Team Outcomes
There is ample evidence indicating that in a healthy pregnant female, exercise has many benefits both physical and mental. As long as the pregnant female has no adverse effects during the pregnancy, almost any type of exercise can be performed- of course- this does require a common-sense approach and avoidance of activities that can lead to falls.
Since pregnant females are routinely followed up by a prenatal nurse or a primary care provider, these professionals are in the ideal position to educate the patient on the benefits of exercise. In addition, the pharmacist should use the opportunity to educate pregnant females who visit a retail pharmacy. Exercise can be continued as long as the pregnant female feels no adverse effects. At the end of the day, the pregnant female should be advised to rest with the legs elevated and wear compression stockings regularly.
1.Du MC, Ouyang YQ, Nie XF, Huang Y, Redding SR. Effects of physical exercise during pregnancy on maternal and infant outcomes in overweight and obese pregnant women: A meta-analysis. Birth. 2019 Jun;46(2):211-221. [PubMed]
2.Chan RS, Tam WH, Ho IC, Kwan MW, Li LS, Sea MM, Woo J. Randomized trial examining effectiveness of lifestyle intervention in reducing gestational diabetes in high risk Chinese pregnant women in Hong Kong. Sci Rep. 2018 Sep 14;8(1):13849. [PMC free article] [PubMed]
3.Ceprnja D, Gupta A. Does muscle energy technique have an immediate benefit for women with pregnancy-related pelvic girdle pain? Physiother Res Int. 2019 Jan;24(1):e1746. [PubMed]
4.Flores D, Connolly CP, Campbell N, Catena RD. Walking balance on a treadmill changes during pregnancy. Gait Posture. 2018 Oct;66:146-150. [PubMed]
5.Guo XY, Shu J, Fu XH, Chen XP, Zhang L, Ji MX, Liu XM, Yu TT, Sheng JZ, Huang HF. Improving the effectiveness of lifestyle interventions for gestational diabetes prevention: a meta-analysis and meta-regression. BJOG. 2019 Feb;126(3):311-320. [PubMed]
6.Klein CP, Dos Santos Rodrigues K, Hözer RM, de Sá Couto-Pereira N, Saccomori AB, Dal Magro BM, Crestani MS, Hoppe JB, Salbego CG, Dalmaz C, Matté C. Swimming exercise before and during pregnancy: Promising preventive approach to impact offspring´s health. Int. J. Dev. Neurosci. 2018 Dec;71:83-93. [PubMed]
7.Ferrari N, Graf C. [Recommendations for Physical Activity During and After Pregnancy]. Gesundheitswesen. 2017 Mar;79(S 01):S36-S39. [PubMed]
8.Perales M, Artal R, Lucia A. Exercise During Pregnancy. JAMA. 2017 Mar 21;317(11):1113-1114. [PubMed]
9.Szumilewicz A. Who and how should prescribe and conduct exercise programs for pregnant women? Recommendation based on the European educational standards for pregnancy and postnatal exercise specialists. Dev Period Med. 2018;22(2):107-112. [PubMed]
10.Dhana K, Haines J, Liu G, Zhang C, Wang X, Field AE, Chavarro JE, Sun Q. Association between maternal adherence to healthy lifestyle practices and risk of obesity in offspring: results from two prospective cohort studies of mother-child pairs in the United States. BMJ. 2018 Jul 04;362:k2486. [PMC free article] [PubMed]
More information: Exercise-induced 3′-sialyllactose in breast milk is a critical mediator to improve metabolic health and cardiac function in mouse offspring, Nature Metabolism (2020). DOI: 10.1038/s42255-020-0223-8 , www.nature.com/articles/s42255-020-0223-8