The right yoga ball size for pregnancy depends on your height. If you’re under 5’4″, use a 55 cm ball. Between 5’4″ and 5’10”, go with a 65 cm ball. Over 5’10”, choose a 75 cm ball. Getting the size right matters because it determines whether your hips sit above your knees, the position that keeps your pelvis properly aligned as your body changes.
How to Check if the Size Is Right
The height chart gives you a starting point, but inflation level affects the fit just as much as the diameter printed on the box. When you sit on the ball, your hips should be noticeably higher than your knees. This forward-tilting position makes it easier to widen your pelvis and takes pressure off your lower back. If your knees are level with or higher than your hips, the ball is either too small or underinflated.
Most balls ship with a pump and can be adjusted. Inflate it until you can sit comfortably with both feet flat on the floor and your thighs angling gently downward. A ball that’s too firm will feel unstable, while one that’s too soft will let you sink and lose that hip-above-knee alignment. You may need to add or release air as your pregnancy progresses and your weight shifts.
Why This Ball Helps During Pregnancy
Sitting on an exercise ball does more than replace your desk chair. The upright, slightly forward-leaning posture encourages your pelvis to open and flex, giving your baby more room to move into a head-down position as your due date approaches. It also strengthens pelvic floor muscles, the muscles you’ll rely on heavily during the pushing stage of labor.
Gravity plays a role too. When you sit upright on a ball rather than reclining on a couch, your baby’s weight naturally encourages descent into the birth canal. Gentle movements like hip circles, rocking side to side, or bouncing lightly can relieve lower back pain and help your body practice the kind of mobility that’s useful during labor. Many people start using the ball in the second trimester for comfort and continue through labor itself.
Birthing Ball vs. Regular Yoga Ball
You’ll see products labeled “birthing ball” and “exercise ball” that look nearly identical, and functionally they overlap. The key differences come down to surface texture and burst resistance. Balls marketed for pregnancy or birthing typically have a slightly textured, non-slip surface so you won’t slide on a smooth floor. They’re also more likely to be tested for slow-deflation, meaning if punctured, they lose air gradually rather than popping. Look for a ball that specifically mentions anti-burst construction and has passed a safety certification like SGS testing.
A standard yoga or gym ball can work fine as long as it meets those two criteria: non-slip surface and anti-burst design. Skip any ball that doesn’t list a weight rating or that feels thin and plasticky when inflated. You want thick, durable rubber that can comfortably support your full body weight plus some bouncing.
Quick Size Reference
- Under 5’4″: 55 cm ball
- 5’4″ to 5’10”: 65 cm ball
- Over 5’10”: 75 cm ball
The 65 cm size fits the widest range of people and is the most commonly sold. If you’re right on the boundary between two sizes, going one size up usually works better than sizing down, since you can always deflate a larger ball slightly but can’t make a smaller one taller.
Tips for Safe Use
Place the ball on carpet or a yoga mat rather than a hard, slippery floor. For the first few sessions, keep a wall or sturdy piece of furniture within arm’s reach until you feel confident with your balance. As your center of gravity shifts in the third trimester, stability becomes more of a challenge, so having something nearby to grab is a practical precaution rather than a sign you’re doing it wrong.
Avoid sitting on the ball for hours at a stretch. Twenty to thirty minutes at a time gives you the postural benefits without fatiguing the small stabilizing muscles in your core and back. If you’re using it at a desk, alternate between the ball and a regular chair throughout the day. And check the ball’s surface periodically for wear, scuffs, or small nicks, especially if you have pets. Even anti-burst balls lose their slow-deflation reliability if the rubber is compromised.