During pregnancy, most exercise is not only safe but recommended. The short list of activities to genuinely avoid includes contact sports, scuba diving, exercises done flat on your back (especially after the first trimester), traditional ab exercises like crunches, and anything in extreme heat or at high altitude. Beyond those clear no-go categories, the real goal is adjusting how you move rather than stopping movement altogether.
Contact Sports and High-Impact Activities
Sports that carry a risk of being hit in the abdomen are off the table for the duration of pregnancy. That includes basketball, soccer, ice hockey, boxing, and martial arts. The concern is straightforward: a blow to the belly can cause placental abruption, where the placenta separates from the uterine wall, which is a medical emergency.
Activities with a high risk of falling also make the list. Downhill skiing, horseback riding, gymnastics, and mountain biking all pose enough fall risk that the potential consequences outweigh the benefits. As your center of gravity shifts forward through pregnancy, your balance changes in ways that can catch you off guard, making falls more likely even in activities you previously handled with ease.
Why Scuba Diving Is Completely Off Limits
Scuba diving is one of the few activities that’s an absolute no at every stage of pregnancy. The reason comes down to how a fetus handles pressure changes underwater. When a diver ascends, tiny gas bubbles can form in the blood. In an adult, the lungs filter these bubbles out before they cause harm. A fetus, however, has a circulatory system designed to bypass the lungs entirely, since oxygen comes through the placenta instead. Without that lung filtration, gas bubbles could enter the fetal bloodstream and potentially cause arterial gas embolism.
There’s an additional risk: the pressure changes at depth can begin to close a critical blood vessel (the ductus arteriosus) that normally stays open until birth. Premature closure of this vessel has been linked to fetal heart failure. No depth or dive duration has been established as safe, so the guidance from the Divers Alert Network is to avoid all recreational diving throughout pregnancy.
Exercises Flat on Your Back
After the first trimester, lying flat on your back during exercise becomes a problem. As the uterus grows, it presses on a major blood vessel called the inferior vena cava when you’re in the supine position. This compression reduces blood flow returning to your heart, which can drop your blood pressure and decrease blood flow to the fetus. You might feel dizzy, lightheaded, or nauseous, though some women feel nothing while the fetal blood supply is still affected.
This means traditional floor exercises like bench presses, supine leg lifts, and lying hip bridges need modification. Incline the bench to at least a 30-degree angle, or switch to side-lying or standing variations. The same applies to yoga poses that keep you flat on your back for extended holds and any Pilates work done in the supine position.
Traditional Core Exercises
Crunches, sit-ups, full planks, and double leg lifts all generate significant intra-abdominal pressure that pushes the abdominal wall outward. During pregnancy, the two halves of your rectus abdominis (the “six-pack” muscle) naturally separate to make room for the growing uterus. This separation, called diastasis recti, affects most pregnancies to some degree. Exercises that bulge, cone, or dome the abdomen make the separation worse and can slow recovery after birth.
Specific movements to skip include crunches and sit-ups of any kind, unmodified planks and push-ups, boat pose in yoga, and scissors or double leg lifts in Pilates. A good visual cue: if you can see your belly forming a ridge or cone shape during an exercise, that movement is creating too much outward pressure. Core work isn’t off limits entirely, but it should focus on deep stabilizing muscles through exercises like pelvic tilts, bird dogs, and modified side planks that keep the abdominal wall from bulging.
Hot Yoga, Saunas, and Exercising in Heat
Raising your core body temperature too high during pregnancy has been linked to birth defects and pregnancy complications, particularly in the first trimester when fetal organs are forming. Hot yoga (typically practiced in rooms heated to 95-105°F), Bikram yoga, and exercising in saunas or steam rooms all push your internal temperature up in ways that are difficult to self-regulate.
Exercising outdoors in high heat and humidity carries similar risks. If you live in a hot climate or exercise during summer months, move your workouts to early morning or evening, stay well hydrated, and move indoors to air conditioning when possible. Regular-temperature yoga classes are fine, as is moderate exercise in comfortable environments.
High Altitude Without Acclimatization
If you’re not already living at elevation, exercising above 8,250 feet (2,500 meters) is generally discouraged during pregnancy, at least in the first four to five days of exposure. At high altitude, the air contains less oxygen, and your body needs time to compensate. During pregnancy, your cardiovascular system is already working harder to supply oxygen to the fetus, so adding altitude stress on top of that can reduce fetal oxygen supply. If you’re traveling to a mountain destination, keep workouts at lower elevations for the first several days and avoid strenuous activity until you’ve had time to adjust.
How Loose Joints Change Your Risk
During pregnancy, your body produces higher levels of a hormone called relaxin, which loosens the ligaments in your pelvis to prepare for birth. But relaxin doesn’t target only the pelvis. It affects connective tissue throughout your body, reducing collagen density in ligaments and making joints less stable. Women have relaxin receptors in multiple joints including the hips and knees, and higher relaxin levels correlate with increased musculoskeletal injuries.
This means activities involving rapid direction changes, jumping, or jerky movements carry more injury risk than usual. Sports like tennis, racquetball, and basketball (which you’d already be avoiding for contact reasons) demand quick lateral cuts that stress the knee’s ACL, a ligament that’s already more vulnerable during pregnancy. Even if you were an experienced athlete before pregnancy, this isn’t the time for explosive plyometrics, heavy single-leg work, or aggressive stretching that pushes joints toward their end range. Your joints will feel more flexible, but that flexibility comes from structural loosening, not improved mobility.
Heavy Lifting and Breath-Holding
Strength training during pregnancy is beneficial for most people, but the way you lift matters more than usual. The Valsalva maneuver, where you hold your breath and bear down to push through a heavy rep, creates a spike in cardiovascular strain that remains poorly understood in pregnant populations. Some research suggests it can be tolerated, but the potential for blood pressure swings and reduced blood flow to the uterus makes it a risky trade-off.
The practical adjustment is to use weights you can lift while breathing continuously, exhaling on the effort phase. If you can’t complete a rep without holding your breath, the load is too heavy for pregnancy training. This typically means reducing your working weight and increasing reps. Avoid maximal lifts and any set where you’re straining to finish the last repetition.
How to Gauge Your Intensity
You may have heard about keeping your heart rate below 140 beats per minute during pregnancy. That guideline is outdated and no longer recommended. Resting heart rate increases by 10 to 20 beats per minute over the course of pregnancy, often a 20% to 25% jump by the third trimester. Because of this natural rise, heart rate alone is a poor measure of how hard you’re actually working.
The better tool is the talk test: if you can carry on a conversation while exercising, you’re at an appropriate intensity. If you’re gasping for words or can only get out a few syllables between breaths, dial it back. This simple check accounts for the cardiovascular changes of pregnancy automatically and works regardless of the activity.
Warning Signs to Stop Immediately
Regardless of what exercise you’re doing, certain symptoms mean you should stop right away and contact your care provider. These include vaginal bleeding, fluid leaking from the vagina, chest pain, dizziness or feeling faint, a sudden headache, regular painful contractions, calf pain or swelling, muscle weakness that affects your balance, or a noticeable decrease in your baby’s movements. Rapid or irregular heartbeat and difficulty breathing that doesn’t resolve when you slow down are also reasons to stop. If something feels wrong even without a specific symptom on this list, trust that instinct and get checked.