If you are an athlete or have an active lifestyle, you may have wondered: ‘Should my exercise routine change during pregnancy and breastfeeding?’ As a former division 1 athlete, I sure have. You may have seen the news about athletes who compete at the highest level during or shortly after pregnancy. Serena Williams won the Australian Open while 8 weeks pregnant. Alysia Montano ran the 800-meter race at a national meet in her third trimester. Allyson Felix won a gold medal at the World Championship in track only 10 months after delivering her baby. At the same time, you may hear concerns about intense physical activity during pregnancy. So, what is the recommendation for pregnant women who have an active lifestyle?

Benefits of Exercise

Most healthcare providers recommend exercise during pregnancy as part of a healthy lifestyle. Women who are active before pregnancy can usually continue these activities during and after pregnancy. Since everyone is different with different medical histories, ALWAYS have a discussion with your healthcare providers about what exercise is best for you.

In general, exercising during pregnancy might lower the chances of preterm delivery (birth before week 37) and low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). It might also help to lower the chance of diabetes and high blood pressure.

In addition, physical activity might help with the muscle aches of pregnancy as well as postpartum depression. Exercising in general has not been known to increase the chances of miscarriage, birth defects, or other pregnancy-related problems.

Studies looking at exercise during pregnancy have not looked at intense exercise specifically.

Level of Activity

Some changes to your routine may be needed because of normal changes in your body during pregnancy. Talk with your healthcare provider about your exercise routine. This is even more important for women who have pre-existing health conditions.

It is important to listen to your body during pregnancy. Every woman and every pregnancy is different. Your body goes through many changes during pregnancy:

• Blood volume increases
• Heart pumps harder
• Heart rate increases
• Fitness level decreases

Many women experience nausea and fatigue throughout their pregnancy making exercise more difficult and harder to maintain proper nutrition and hydration. Listen to your body, do not push it past its limits.

It is difficult to compare vigorous exercise between people. Jogging 10 miles may seem like a piece of cake for a marathon runner while it can be difficult for an Olympic lifter. For this reason, vigorous activity is most frequently defined as up to 85% of capacity. While maximum effort is difficult to measure, capacity is often described in terms of heart rate.

Another way to check your intensity level is the “talk test.” If you are breathing hard but can still have a conversation easily—but you cannot sing, that is moderate intensity. An activity would be considered vigorous if you can only say a few words before pausing for a breath.

If you were in the habit of doing vigorous exercise before your pregnancy, it can be continued for most healthy women during pregnancy according to experts. However, there is limited information on individuals who exceed the accepted 85% capacity. An upper level of ‘safe’ exercise intensity has not been established.

 In general, ACOG recommends aiming for at least 150 minutes (2 hours and 30 minutes) of moderate intensity aerobic activity spread out over a week. For most people, keeping your heart rate at or below 140 beats per minute is considered moderate intensity.

What to Consider When Exercising

Below is some general information to consider and discuss with your healthcare provider. Remember, everybody is different. Always discuss your specific exercise program with your healthcare providers, who know your specific medical history and how your pregnancy is progressing.

• Stick with what your body is used to. If you are used to long-distance running, pregnancy is not the time to turn into a power lifter.
• Stay hydrated. Drink plenty of fluids before, during and after exercising.
• Avoid overheating. Even if you are used to exercising in 90-degree heat, you may have to look for an alternative method such as air-conditioned gyms. Do not use steam rooms, hot tubs, or saunas.
• Avoid exercises lying flat on your back in the second and third trimester of pregnancy. This allows less blood flow to your womb.
• Do not engage in sports where you can fall, get injured, or get hit in the abdomen.
• Reduce weight load. Holding your breath during heavy lifts can result in baby’s heart rate slowing down. Because of this, you may have to reduce the weight.
• Allow enough time for your body to recover after each training session.
• Make sure you get enough calories. If you regularly participate in intense exercise, you might have to adjust your nutrition.
• Continue to fuel your body. Long, intense exercise can result in low blood sugar. Make sure you continue to fuel your body if you plan on exercising for over 45 minutes.
• Check with your healthcare provider before continuing or starting any supplements.
• Stop exercising if you:

  • Feel dizzy
  • Have a headache
  • Develop chest pain or swelling
  • Have muscle cramps
  • Experience vaginal bleeding
  • Have leakage of fluid
  • Feel contractions
  • Have shortness of breath before exertion.

• Call your healthcare provider with any concerns.

Postpartum and Breastfeeding

Make sure you talk with your healthcare provider about when to start exercising after birth. Exercise can be resumed slowly after delivery as soon as it is medically safe. When exercise can be resumed varies among women, with some being able to start exercising within days after delivery. This may depend on if delivery was a c-section vs. vaginal birth and any additional health problems or complications.

Healthcare providers will tell you it is important to remain hydrated while breastfeeding, especially when exercising. The amount of nutrition you need may also change depending on the level of your activity during breastfeeding.

At the end of the day, all athletes have different needs during pregnancy and after the baby is born. There is no ‘one-size-fits-all’ for exercising during pregnancy. The best thing you can do is talk with your healthcare provider and listen to your body. For more information, see our MotherToBaby fact sheet on exercising here. You can also find more information on exercise during pregnancy here.

Originally written 8/18/20, Updated 9/24/26

Sara contacted us at the recommendation of her OB/GYN to talk about the paroxetine she takes for her depression. Sara wanted to see if taking paroxetine can increase the chance of having a baby with a heart defect. She was confused because her genetic screening result was normal. She asked: “Is it possible for my baby to have a heart defect if my non-invasive prenatal testing (NIPT) was negative?” 

There are many tests that can check on the development of your baby during pregnancy. It can be difficult to keep track of what they are looking for. Knowing the differences between a birth defect and a chromosomal condition can help you understand these tests.

What are birth defects and how can you look for them?

Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. Certain exposures, like medications, can increase the chance of birth defects. Most birth defects happen during the first trimester when the baby’s organs (body parts) are developing. A certain organ might look or work differently. You may have heard of a baby being born with a hole in the heart. This is a common birth defect. Ultrasounds during pregnancy can look for birth defects. Read more about ultrasounds through our blog here. Most women will have an anatomy ultrasound between 18 and 22 weeks of pregnancy. You might know this as the time when you can learn the sex of the baby. The goal of this ultrasound is to take a detailed look at the baby’s organs to check for birth defects. It will also check the growth of the baby. While this is an important screening test, it is not perfect. A normal anatomy ultrasound does not rule out the baby having a birth defect or other pregnancy-related problems.

A birth defect can be an isolated finding, meaning that there are no other related health problems. A birth defect might be caused by a change in the baby’s genetic information, such as a chromosomal condition.

What are chromosomal conditions and how can you look for them?

Chromosomal conditions are genetic, meaning they are a change in the baby’s genetic information. Chromosomal conditions do not usually run in families and are not inherited. Chromosomes are like a recipe book that holds all the recipes for the development of the baby. If a certain recipe calls for one stick of butter, but the book accidentally says two sticks of butter, the recipe will turn out differently. In the same way, sometimes people have extra or missing chromosomes that can cause changes in development. For example, people who have a chromosomal condition known as Down syndrome have three copies of chromosome 21 rather than two. This extra amount of genetic information causes developmental differences. Babies that have Down syndrome sometimes also have birth defects that are seen on ultrasound. Other babies that have Down syndrome can have normal ultrasounds. Therefore, ultrasound is not the best way to screen for chromosomal conditions.

Your healthcare provider will offer you screening for the most common chromosomal conditions. Testing for a chromosomal condition includes a screen called NIPT or diagnostic testing through procedures called CVS (chorionic villi sampling) or amniocentesis. NIPT involves drawing blood from you as early as 8-10 weeks of pregnancy. NIPT can tell you if you have a high or low chance of having a pregnancy with certain chromosomal conditions. Diagnostic testing can tell you “Yes” or “No” about your baby having a chromosomal condition. Diagnostic testing involves a procedure that might come with small risks to the pregnancy. These screens and tests are optional. Your healthcare provider might suggest you meet with a genetic counselor. Genetic counselors can talk with you about the pros and cons of these tests, help with decision making and interpret the results. 

During our conversation, Sara asked: “So because my NIPT results were low risk, the baby is unlikely to have a chromosomal condition. However, a birth defect could have happened in the first trimester, and I need to wait until my anatomy scan to get those results. Is that right?” That is exactly right! Although some studies show an increased chance of heart defects with paroxetine use in pregnancy, most other studies do not show an increased risk. If there is an increased chance of birth defects with paroxetine use in the first trimester, it is expected to be small. See our factsheet on Paxil® for more detail.

Sara shared that she was feeling more knowledgeable about the difference between a birth defect and a chromosomal condition. She was relieved that her NIPT results showed low risk. She also felt more confident heading to her anatomy scan knowing that this test, while not perfect, would be the best way to identify birth defects during pregnancy. 

If you have any questions about exposures during pregnancy, contact MotherToBaby. To find a genetic counselor in your area, visit the Find a Genetic Counselor page on the National Society of Genetic Counselors website.

Originally published 10/31/23, Updated 6/3/26 by Nevena Krstic and Reka Muller