Biking during pregnancy is generally safe, but the type of biking matters. Stationary cycling has been extensively studied and is listed by the American College of Obstetricians and Gynecologists (ACOG) as a safe and beneficial exercise during pregnancy. Outdoor cycling carries more risk because of balance changes and the possibility of falls. The distinction between the two becomes increasingly important as pregnancy progresses.
What Makes Stationary Cycling a Good Option
ACOG recommends at least 150 minutes of moderate-intensity aerobic activity per week during pregnancy, and stationary cycling is one of the exercises the organization specifically highlights as safe and well-studied. There’s no fall risk, you control the intensity, and you can stop the moment something feels off.
The benefits go beyond general fitness. In a clinical trial of overweight and obese pregnant women, those who cycled for at least 30 minutes three times per week starting early in pregnancy had a gestational diabetes rate of 22%, compared to 40.6% in the group that didn’t exercise. The cycling group also gained less weight throughout pregnancy (about 8.4 kg versus 10.5 kg by delivery) and had lower insulin resistance at 25 weeks.
Why Outdoor Cycling Gets Riskier
Pregnancy changes two things that matter on a bike: your balance and your joints. The extra weight in front of your body shifts your center of gravity forward, making you less stable. At the same time, pregnancy hormones loosen the ligaments that support your joints, making them more mobile and more vulnerable to injury. ACOG specifically notes that riding a standard bicycle during pregnancy can be risky because of these balance changes.
In the first trimester, when your body hasn’t changed much physically, outdoor cycling on familiar, flat routes is a reasonable option for experienced riders. By the second and third trimesters, the shift in center of gravity becomes more pronounced, and the consequences of a fall are more serious. Many women who ride outdoors early in pregnancy transition to a stationary bike as their belly grows.
How Hard You Should Push
Intensity matters more than you might expect. ACOG recommends exercising at a “fairly light to somewhat hard” level, keeping your heart rate below 60 to 80% of your age-predicted maximum. As a general ceiling, that usually means staying under 140 beats per minute.
The simplest way to gauge this is the “talk test”: if you can carry on a conversation while pedaling, you’re in the right zone. If you’re too breathless to talk, you’re pushing too hard.
Research on fetal response backs this up. During moderate maternal exercise, a baby’s heart rate increases slightly, which is normal and temporary. But when mothers exercised above roughly 90% of their maximum heart rate increase, fetal heart rate actually dropped in some cases, and fetal movement decreased. In two cases of near-maximal exertion, researchers observed temporary fetal distress, including slowed heart rate and reduced movement for about 20 minutes afterward. Moderate cycling is safe for the baby. Pushing to your limit is not.
Adjusting Your Bike Setup
As your belly grows, especially in the third trimester, you’ll likely need to raise the handlebars on a stationary bike. Lower handlebars force you to lean forward, which adds strain to your neck, mid-back, and lower back at a time when the weight of the baby is already pulling your center of gravity forward and down. Raising the bars lets you sit more upright and reduces that load.
Pelvic changes can also affect comfort on the saddle. As the pelvis widens in mid to late pregnancy, seated pressure on the pelvic floor increases. A wider, more cushioned saddle can help, and standing periodically during your ride takes pressure off entirely. If you notice pain or significant discomfort in the pelvic area while cycling, that’s a signal to modify your position or take a break from the bike.
When to Stop Riding
Certain symptoms during any exercise, cycling included, mean you should stop immediately: regular painful contractions, vaginal bleeding, unusual shortness of breath, dizziness, headache, chest pain, or calf pain or swelling. These can signal complications that need medical attention.
There are also some conditions that rule out aerobic exercise entirely during pregnancy. Women with certain heart or lung conditions, cervical insufficiency, placenta previa after 26 weeks, preeclampsia, or preterm labor in the current pregnancy are typically advised not to exercise. A clinical evaluation before starting or continuing a cycling routine helps identify whether any of these apply to you.
Practical Guidelines by Trimester
- First trimester: Most women can continue their pre-pregnancy cycling routine, including outdoor riding, with minimal changes. Nausea and fatigue may naturally limit your intensity. This is a good time to establish a consistent habit if you weren’t already active.
- Second trimester: Your center of gravity starts shifting noticeably. Consider transitioning to a stationary bike if you’re still riding outdoors, particularly on uneven terrain or in traffic. Raise handlebars as needed and listen to pelvic floor feedback.
- Third trimester: Stationary cycling is the safer choice. Your balance is significantly altered, joints are at their loosest, and the belly makes a standard bike frame awkward to mount and ride. Adjust the bike for a more upright position, keep intensity moderate, and shorten sessions if fatigue sets in. Many women ride comfortably into the final weeks, while others find it impractical past 36 or 37 weeks.
Women who were physically active before pregnancy can generally continue cycling throughout, adjusting as their body demands. Women new to exercise can start cycling during pregnancy, but should build up gradually rather than jumping into intense sessions. The 150-minute weekly target works well as a goal to work toward, spread across several days rather than crammed into one or two long rides.