Becoming pregnant can motivate women to make healthy lifestyle changes, including sticking with an exercise program. Both mother and baby can reap the rewards from getting regular physical activity.
It's safe for most women to exercise during pregnancy, said James Pivarnik, a professor of kinesiology and epidemiology at Michigan State University in East Lansing who has researched exercise and pregnancy.
The nine months can be a good time for women who haven't been physically active to get started with light activity, while women who have already been exercising prior to pregnancy can remain active to maintain their fitness level as long as they're feeling good, Pivarnik told Live Science.
He said the amount and types of workouts that well-conditioned athletes can continue to comfortably do during pregnancy is very individualized and should be discussed on a case-by-case basis with a woman's doctor.
The Physical Activity Guidelines for Americans, published by the U.S. Department of Health and Human Services, recommends that, to gain substantial health benefits, healthy women who are not already highly active or doing vigorous-intensity activity get at least 150 minutes (2 hours and 30 minutes) of moderate-intensity physical activity each week during pregnancy and the postpartum period. This amounts to about 20 to 30 minutes each day. It doesn't have to be done all at once; it can be divided up into several shorter sessions sprinkled throughout the day.
According to the guidelines, examples of vigorous-intensity activities include running or jogging, while moderate-intensity activities involve working at an effort equivalent to brisk walking.
Pregnant women who are highly active or already do vigorous-intensity aerobic activity can continue to exercise during and after their pregnancy, as long as they remain healthy and discuss with their doctor how and when the amount of physical activity should be adjusted over time, the guidelines suggest.
The guidelines also state that the risks of moderate-intensity activity by healthy women during pregnancy are very low, and it does not increase their risk of having a low-birth-weight baby, preterm delivery or miscarriage.
Being active during pregnancy has benefits that help strengthen a woman's body and mind, according to the American College of Obstetricians and Gynecologists (ACOG).
Research has shown that physical activity reduces the risk of pregnancy complications, including pre-eclampsia (high blood pressure and protein in the urine after the 20th week of pregnancy) and gestational diabetes (pregnancy-related diabetes), Pivarnik said. It can also help reduce the odds of labor and birth complications, and decrease the risk of preterm delivery, he said.
Small studies suggest that being active during pregnancy can reduce symptoms of depression. In a 2012 study involving 80 women in Colombia who were pregnant for the first time, those who completed three months of a supervised aerobic exercise program showed fewer depressive symptoms than members of the control group, who continued usual activities and performed no specific exercise. The results were published in the Journal of Physiotherapy.
Staying fit has other payoffs to pregnant women, according to ACOG, including:
- Fewer pregnancy-related discomforts, such as backaches, bloating, constipation, leg pain and swelling
- Better mood
- Increased energy
- Improved sleep
- Promotes blood circulation
- Increased stamina, muscle tone and strength, which prepares the body for labor and childbirth
How body changes during pregnancy may affect exercise
According to the March of Dimes, here are some specific ways that being pregnant can influence the way a woman feels when she's physically active:
- More oxygen is needed during pregnancy, and a woman's expanding belly puts pressure on the lungs, making them work harder. This could make a mother-to-be feel short of breath during her workout, especially during the second and third trimesters.
- The heart beats quicker and works harder to ensure the baby gets oxygen, so a woman may tire sooner during her workout.
- An expanding belly and carrying extra body weight in the front of a woman's body may affect her sense of balance. It will also shift her center of gravity and can put more stress on joints and muscles in her lower back and pelvis.
- Pregnant women may have looser joints and ligaments, due to hormonal changes. This may make the joints more mobile and less stable, increasing the risk of injury.
- Sweating starts at a lower body temperature than prior to pregnancy, to protect both mother and baby from getting overheated. Expecting mothers should drink plenty of water while exercising to prevent getting dehydrated.
- Breast size may increase, so it's helpful to wear a sports bra that gives more support and fits well.
- Feet may swell during pregnancy because of fluid retention, resulting in a need for a larger size shoe.
Best exercises during pregnancy
For a woman who has not been getting regular exercise prior to pregnancy, Pivarnik recommended getting a good pair of sneakers or walking shoes and starting a walking program. Some other low-impact activities include stationary biking and yoga (except for poses that involve lying on the back).
For pregnant women who are experiencing back or knee pain, Pivarnik suggested swimming or water walking to take weight off the joints.
A fairly sedentary pregnant woman should gradually work her way up to 150 minutes of moderate-intensity activity a week, he said. She might start with 5 to 10 minutes a day of walking, and add 5 minutes more to her daily walk each week until reaching 30 minutes a day.
There's some evidence that pregnant women who exercise and keep it up after they deliver might not gain as much weight during pregnancy and have an easier time losing it once the baby arrives, Pivarnik said.
Activities to avoid during pregnancy
Some activities may not be safe for pregnant women to do, according to the March of Dimes. These include:
- Exercises that involve lying on the back, such as sit-ups or some yoga poses, after the first trimester. Lying on the back can be risky because it can limit blood flow to the baby.
- Activities that increase the risk of falling, such as horseback riding, bike riding, downhill skiing, surfing, snowboarding, skating or gymnastics.
- Contact sports in which a woman could get hit in the stomach, such as soccer, basketball, ice hockey or kickboxing.
- Scuba diving, which can put an unborn baby at risk for decompression sickness. This illness may create dangerous gas bubbles in the baby's blood.
- High-altitude (more than 6,000 feet) exercising, which can reduce the amount of oxygen received by the baby.
- Exercising outdoors on hot, humid days that can cause a woman's body to overheat. For the same reason, pregnant women should also stay out of saunas, hot tubs and steam rooms, and should also avoid doing Bikram (or hot) yoga.
Warning signs to stop exercising
The American College of Obstetricians and Gynecologists advises pregnant women to stop exercising and call their doctors immediately if they experience any of the following 10 symptoms during or following a workout:
- chest pain
- calf pain or swelling (which may indicate a blood clot)
- decreased fetal movement
- dizziness or feeling faint
- fluid leaking from the vagina
- headache that is severe or won't go away
- muscle weakness
- preterm labor (having premature contractions at least three weeks before a woman's due date)
- shortness of breath
- vaginal bleeding
When exercise isn't safe
It may not always be safe for pregnant women to exercise. According to the Mayo Clinic, women should discuss with their doctors whether being physically active is advisable in the following situations:
- A multiple pregnancy (such as twins or triplets) at risk for preterm labor
- Preterm labor during current or most recent prior pregnancy
- Vaginal bleeding
- Some forms of heart and lung disease
- Cervical problems, such as an incompetent cervix, which is when the cervix opens too early
- Find answers to frequently asked questions about exercise during pregnancy from the American Congress of Obstetricians and Gynecologists.
- The March of Dimes provides tips and information about being healthy during pregnancy.