Place a pillow between your knees, thighs, and feet so your upper leg sits level with your pelvis and mirrors the position of your bottom leg. This keeps your spine neutral and takes pressure off your hips and lower back. Getting the placement right makes a real difference in sleep quality, especially as your belly grows, so here’s how to do it properly at each stage.
Why a Pillow Between Your Legs Helps
When you lie on your side without any support, your top leg drops forward and down. That pulls your pelvis into a twist, which tugs on your lower back and compresses the hip you’re lying on. During pregnancy, the hormones that loosen your joints for delivery also make your pelvis less stable, so this twisting effect is amplified. A pillow between your legs eliminates the drop by holding your upper leg even with your hip socket, keeping your spine in a straight, neutral line from your neck to your tailbone.
This matters most for two common pregnancy complaints. The first is general lower back pain, which worsens as your center of gravity shifts forward. The second is pelvic girdle pain (sometimes called symphysis pubis dysfunction), where the joint at the front of your pelvis becomes inflamed and painful. For both, side-lying with proper leg separation reduces the strain that aggravates symptoms overnight.
Step-by-Step Positioning
Start by lying on your side with your hips stacked directly on top of each other. Bend both knees to a comfortable angle, roughly 90 degrees or slightly less. Then slide a pillow between your legs so it contacts three areas: your inner thighs, your knees, and your ankles or feet. The goal is for your top leg to be completely parallel to the bottom one, as if you were standing upright but lying down.
A common mistake is wedging a thin pillow only between the knees. This leaves your thighs angled inward and your ankles touching, which doesn’t fully correct pelvic tilt. The pillow (or pillows) should be thick enough that your upper leg sits at the same height as your hip. For most people, a standard bed pillow folded in half works, but a firmer, fuller pillow holds its position better through the night.
Adding Belly Support
As your pregnancy progresses, your bump can pull your torso forward when you’re on your side, creating a different source of strain. Place an extra pillow or a rolled-up towel under your belly to take the weight off. This reduces pull on your round ligaments (the bands that connect your uterus to your groin area) and places less strain on your hips and lower back. With one pillow between your legs and another tucked under your bump, your body is supported at every point where gravity would otherwise drag you out of alignment.
When to Start
There’s no fixed week when you need to begin. Most women find sleep positioning becomes uncomfortable around week 20, when the belly starts expanding noticeably. That’s a natural time to introduce a pillow between your legs. But if you’re experiencing hip or back pain earlier, there’s no reason to wait. Some women with pelvic girdle pain start as early as the first trimester and find immediate relief.
Left Side vs. Right Side
You may have heard that sleeping on your left side is essential to avoid compressing a major blood vessel (the vena cava) that returns blood to your heart. The reality is more nuanced. While lying flat on your back can cause lightheadedness in some pregnant women, only about 2% to 4% of those who feel symptoms have significant compression, and even in that small group, research published in the Journal of Obstetrics and Gynaecology Canada found no evidence of harm to the baby. Sleep on whichever side is comfortable. The pillow between your legs works identically on both sides.
Choosing the Right Pillow
You don’t need a specialty product. A firm standard pillow works well, especially if you fold or bunch it to the right thickness. That said, pregnancy-specific pillows are designed to stay in place all night, which is their main advantage. Here’s how the common shapes compare:
- U-shaped pillow: Wraps around both sides of your body with two long arms running from your head down to your feet. Best if you switch sides frequently at night, because you don’t need to reposition anything when you roll over. It supports your back, belly, and legs all at once.
- C-shaped pillow: Curves around one side of your body, supporting your head, belly, and legs in a single piece. More flexible in how you can position it, and takes up less bed space than a U-shape. Also useful for nursing after delivery.
- Standard bed pillow: The simplest option. Place one between your legs and a second under your belly. You may need to readjust when switching sides, but it costs nothing extra and works perfectly well.
The thickness matters more than the shape. If a pillow compresses flat under the weight of your leg, it’s not providing enough separation. Memory foam or dense fiberfill holds its loft better through the night than a soft down pillow.
Troubleshooting Common Problems
The Pillow Slides Out Overnight
This is the most frequent complaint. A full-length body pillow or U-shaped pillow solves it because it’s anchored at your head and extends past your feet, so there’s nothing to slip. If you’re using a standard pillow, try wearing snug pajama pants or leggings. The fabric friction helps keep the pillow from migrating. You can also place a second pillow behind your back to keep yourself from rolling, which reduces the movement that dislodges the leg pillow.
Your Hips Still Ache
If you’ve got the pillow positioned correctly and your hips still hurt, the mattress may be the issue. Side sleeping concentrates your body weight on a smaller surface area, and a too-firm mattress creates pressure points at the hip and shoulder. A mattress topper with a few inches of give can make a significant difference. You can also try placing a thin pillow or folded blanket under your waist (the dip between your ribs and hip) to prevent your spine from sagging sideways.
Pelvic Girdle Pain Worsens at Night
For pelvic girdle pain specifically, keep your knees together when turning over in bed. Rather than swinging one leg over the other, squeeze the pillow between your knees and roll your entire body as a unit. Separating your legs during the turn is what aggravates the pubic joint. Some women find it helpful to sleep with a satin or silk pillowcase on the leg pillow, which reduces friction and makes it easier to shift positions without jarring movements.