A peanut ball is a large, inflatable ball shaped like a peanut shell, with two rounded ends and a narrow indentation in the middle. It’s most commonly used during labor and delivery, where it’s placed between a laboring person’s legs to help open the pelvis and speed up birth. Outside of childbirth, it’s also a popular tool in pediatric physical therapy and occupational therapy for building core strength and balance.
Shape, Size, and Design
Unlike a standard round exercise ball, a peanut ball has a double-lobed shape that keeps it from rolling away. That narrow center channel is what makes it useful: your leg can hook around the middle, holding the ball in place without anyone needing to steady it. The shape also limits the ball to rolling forward and backward rather than in every direction, which makes it more stable and safer for people who have limited mobility or balance challenges.
Peanut balls come in four common sizes, ranging from about 40 cm to 85 cm. A 40 cm ball is roughly 26 inches long and 16 inches across the center, while an 85 cm ball stretches to about 52 inches long and 34 inches across. The right size depends on the person’s height and how the ball will be used. Most are made from durable, latex-free vinyl that can be cleaned and sterilized between uses.
How It’s Used During Labor
The peanut ball’s primary claim to fame is in the delivery room. During labor, especially when an epidural limits your ability to move around, the ball is placed between or below your knees while you lie on your side or recline in bed. This does something simple but important: it holds your legs apart and tilts your pelvis into a more open position, similar to a squat. That extra space in the pelvis gives the baby more room to rotate and descend through the birth canal.
There are two main positions. In the side-lying position, the ball is placed between your legs so your upper leg rests over or hooks around the center of the ball. This lifts the top leg and widens the pelvic outlet. In the semi-reclined position, one leg goes over the ball and the other rests beside it, with the ball pushed up toward your hips. This version is typically used to encourage dilation and help the baby move downward.
Nurses or midwives will often reposition the ball and rotate you from side to side throughout labor, which encourages the baby to keep shifting into the best position for delivery.
Why It Matters With an Epidural
An epidural provides excellent pain relief, but it comes with a tradeoff: you can’t get up and move freely. Walking, squatting, and swaying on your feet are all off the table once your lower body is numb. Those movements naturally help open the pelvis and use gravity to assist the baby’s descent, so losing them can slow labor down.
The peanut ball was designed to solve that specific problem. It mimics a squatting position while you’re lying in bed, keeping the pelvis open even when you can’t actively move your legs. The ball can be adjusted to different angles to change how wide the pelvis opens, giving care providers a way to fine-tune positioning throughout labor without requiring you to do anything physically demanding.
What the Research Shows
Several clinical studies have tested whether peanut balls actually make a measurable difference, and the results are consistently positive. A 2025 meta-analysis published in the European Journal of Midwifery found that women with epidurals who used a peanut ball shortened their first stage of labor by an average of 53 minutes compared to those who didn’t use one. Multiple individual studies also found reductions in the second stage of labor, though the exact numbers varied.
The effect on cesarean delivery rates is notable. A study published in The Journal of Perinatal Education found that only 10% of women in the peanut ball group needed a cesarean section, compared to 21% in the control group. After adjusting for other factors, women using the peanut ball were less than half as likely to undergo cesarean surgery. These studies focused on low-risk pregnancies where patients were also receiving epidural anesthesia.
No side effects from peanut ball use have been reported in the clinical literature. It’s a low-cost, non-invasive tool, which is part of why it’s become standard equipment in many labor and delivery units.
Uses Beyond the Delivery Room
Peanut balls have a second life in pediatric therapy. Physical and occupational therapists use them with children to build core strength, improve balance, and develop motor planning skills. The peanut shape provides just enough instability to challenge a child’s trunk muscles without being so wobbly that it feels unsafe, which makes it especially useful for kids with low muscle tone or balance difficulties.
Common exercises include having a child lie on their belly over the ball and reach for toys on the ground, which builds upper body and core strength. Standing with one foot on the ball works on hip and ankle stability. Therapists also roll the ball over a child’s body while they lie on a mat to provide deep pressure input, a technique that can help kids who feel overwhelmed or overstimulated calm down. The ball’s shape keeps it from rolling out from under the child, which means less frustration and fewer falls compared to a round therapy ball.
For adults outside of labor, peanut balls serve similar purposes. They’re used in physical therapy and home exercise programs for core strengthening, seated balance work, and gentle stretching, particularly for people who find a standard exercise ball too unstable to use safely.