Exercise during pregnancy is safe and encouraged, but certain activities carry real risks to you and your baby. The exercises to avoid generally fall into a few categories: those with high impact or fall risk, those that involve lying flat on your back, movements that strain your abdominal wall, and activities in extreme environments like deep water or high altitude.
Contact Sports and High-Fall Activities
Any sport that puts you at risk of a blow to the abdomen is off the table for the duration of pregnancy. That includes ice hockey, boxing, soccer, and basketball. The concern is straightforward: a hit to your midsection can cause placental abruption or direct injury to the uterus, and there’s no safe level of abdominal trauma during pregnancy.
Activities with a significant fall risk are also worth cutting out, even if they feel familiar. Downhill skiing, water skiing, surfing, off-road cycling, gymnastics, and horseback riding all carry enough fall potential that most obstetric guidelines recommend stopping them. Your center of gravity shifts as your belly grows, and a hormone called relaxin loosens the ligaments throughout your body, not just in your pelvis. That combination makes your joints less stable and your balance less reliable than it was before pregnancy, which turns a manageable risk into a much bigger one.
Exercises on Your Back After the First Trimester
Once you’re past about 20 weeks, lying flat on your back becomes a problem. In that position, the weight of your uterus compresses a major blood vessel called the inferior vena cava against your spine. This can reduce the blood returning to your heart by 25 to 30 percent, dropping your cardiac output and potentially limiting blood flow to the baby.
This means traditional floor exercises like flat bench presses, supine leg lifts, and certain yoga poses done on your back should be modified or swapped out. You might feel dizzy, lightheaded, or nauseous, but some women don’t notice symptoms even when blood flow is compromised. The simplest fix is to use an incline or prop yourself at an angle with a wedge or pillows so your back isn’t flat. If a yoga class asks you to hold a position on your back for more than a minute or two, switch to a side-lying alternative.
Crunches, Sit-Ups, and Traditional Core Work
Your abdominal muscles naturally separate during pregnancy to make room for your growing uterus, a condition called diastasis recti. Any movement that forces your abdominal wall to bulge outward can widen that separation and make recovery harder after delivery. The biggest offenders are crunches and sit-ups of any kind.
Several other common core exercises fall into the same category:
- Planks and push-ups without modification
- Double leg lifts and scissors from Pilates
- Boat pose and downward dog in yoga
- Any movement that causes your belly to visibly cone or dome outward
Cleveland Clinic recommends avoiding exercises like sit-ups and crunches that put direct pressure on your abdominals after 12 weeks of pregnancy. That doesn’t mean you should stop all core work. Modified exercises that engage the deep stabilizing muscles of your core and pelvic floor are actually beneficial and can help with labor and recovery. Think gentle pelvic tilts, bird-dogs on all fours, and diaphragmatic breathing exercises rather than anything that forces the outer abdominal muscles to contract hard.
Scuba Diving
Scuba diving is one of the few activities that’s considered fully off-limits at every stage of pregnancy. As you surface from a dive, dissolved gases form bubbles in the bloodstream. Your body can handle this, but a developing fetus has no protection against decompression problems. Research has shown the fetus is at risk of gas embolism and potential malformation from these pressure changes. Snorkeling at the surface is fine, but anything involving pressurized air underwater should wait until after delivery.
Hot Yoga, Hot Pilates, and Overheating
Exercising in high-heat environments raises your core body temperature in ways that can affect fetal development, particularly in the first trimester. Hot yoga and hot Pilates classes, typically held in rooms heated to 95°F or higher, push your body temperature up faster than it can cool down. Overheating (hyperthermia) during early pregnancy has been linked to neural tube defects. Standard-temperature yoga and Pilates classes are generally safe with appropriate pose modifications.
The same caution applies to exercising outdoors in extreme heat or spending extended time in saunas and hot tubs. If you’re sweating heavily and can no longer carry on a conversation, you’re likely working too hard for conditions.
Exercise at High Altitude
If you don’t already live at elevation, exercising above 6,000 feet (about 1,800 meters) during pregnancy adds risk. At higher altitudes, oxygen levels in your blood drop, and your body has to work harder to deliver oxygen to the baby. At elevations around 8,200 feet (2,500 meters) and above, oxygen saturation starts to decrease more steeply, raising the chance of complications.
If you’re visiting a mountain town, experts recommend waiting at least 3 to 4 days to acclimate before exercising, and keeping the intensity at or below your usual level. Vigorous activity at altitude is also associated with dehydration and a higher fall risk. Women who already live at altitude and are acclimatized generally don’t need to make the same adjustments.
Heavy Lifting With Breath-Holding
Strength training during pregnancy isn’t automatically unsafe, but a specific technique common in heavy lifting is. The Valsalva maneuver, where you hold your breath and bear down to push through a heavy rep, creates a sharp spike in abdominal pressure. Early pregnancy exercise guidelines flagged this as a concern because of potential effects on fetal heart rate and blood flow.
If you want to continue lifting, the practical adjustment is to use lighter weights with more repetitions and exhale through the effort rather than holding your breath. Jerky, bouncy, or high-impact movements should also be swapped for controlled, steady motions. Your joints are less stable than usual thanks to the hormonal changes loosening your ligaments, so the risk of a strain or sprain goes up when you lift at your pre-pregnancy max.
Skydiving and Extreme Sports
This one is straightforward. Skydiving, bungee jumping, and similar extreme activities expose you to rapid pressure changes, high-impact landings, and forces your body isn’t designed to handle during pregnancy. These are on every major guideline’s “avoid” list.
How to Monitor Your Intensity
The old rule of keeping your heart rate below 140 beats per minute is outdated and no longer recommended. Instead, the most reliable method is the “talk test”: if you can carry on a conversation while exercising, you’re in a safe range. If you’re too breathless to talk, you should ease up. Clinical settings sometimes use a perceived exertion scale where moderate intensity, the sweet spot for pregnancy, feels like you’re working but not straining.
Target heart rate zones validated for pregnant women do exist and correspond to about 60 to 80 percent of your maximum aerobic capacity, but these vary by age and fitness level. The talk test is simpler, requires no equipment, and works in any setting. Pay attention to warning signs like vaginal bleeding, dizziness, chest pain, calf swelling, headache, or fluid leaking, all of which mean you should stop immediately.