Quick Answer: The best sleeping position during pregnancy is on your left side (SOS, or "sleep on side"), especially in the second and third trimesters. Left-side sleeping maximises blood flow to the uterus, kidneys, and baby by keeping the weight of the uterus off the inferior vena cava (the large vein that returns blood from your lower body to your heart). A pillow between your knees and a supportive mattress make this position significantly more comfortable.
Brad, Owner since 1987: "We have been helping Brantford families sleep better since 1987. Every customer gets personal attention, honest advice, and the kind of follow-up service you just do not get from big box stores."
Sleep during pregnancy is one of those things nobody fully prepares you for. The first trimester, you are exhausted but cannot get comfortable. By the third trimester, every position feels wrong. Your back aches, your hips hurt, and the baby seems to kick hardest right when you are finally drifting off. Finding the right sleeping position is not just about comfort. It matters for blood flow, digestion, and reducing pressure on your growing body.
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Note: This article is for general information only. Always consult your healthcare provider about sleep positions specific to your pregnancy.
Why Left Side Sleeping Is Recommended
The Society of Obstetricians and Gynaecologists of Canada (SOGC) and most obstetric professionals recommend left-side sleeping during pregnancy. The reason is anatomical.
As the uterus grows, it becomes heavy enough to compress the inferior vena cava, the major vein running along the right side of your spine. When you lie on your back, this compression can reduce blood return to the heart, which means less blood flow to the placenta and baby. Lying on the left side shifts the uterus away from this vein.
That said, sleeping on your right side is also fine. The left-side preference is based on theoretical blood flow optimisation, and the difference between left and right is modest for most pregnancies. The important thing is to avoid prolonged back sleeping after about 20 weeks.
What About Back Sleeping?
In the first trimester, sleeping on your back is generally safe. After 20 weeks, most healthcare providers recommend avoiding the back position for extended periods. If you wake up on your back during the night, do not panic. Simply roll to your side. Your body usually signals discomfort before any real issue occurs. Some women feel lightheaded or short of breath when lying on their back later in pregnancy, which is the body's own warning system working correctly.
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Sleeping Position by Trimester
First Trimester (Weeks 1-12)
The good news: any sleeping position is generally safe during the first trimester. The uterus is still small and within the pelvis. The bad news: fatigue and nausea can make sleep difficult regardless of position. If nausea is worse when lying down, try elevating your upper body slightly with an extra pillow or an adjustable bed base.
Second Trimester (Weeks 13-27)
This is when side sleeping becomes more important. The uterus is growing above the pelvis, and back sleeping may start to feel uncomfortable. Many women naturally shift to side sleeping during this period. A pillow between the knees reduces hip and lower back strain.
Third Trimester (Weeks 28-40)
Side sleeping is strongly recommended now. The uterus is at its heaviest, and the vena cava compression risk is real. You will likely need more pillow support: between the knees, under the belly, and possibly behind your back to prevent rolling over. A mattress that contours to your body without creating pressure points becomes genuinely important at this stage.
Mattress Support During Pregnancy
Pregnancy changes your body's relationship with your mattress. Weight increases, your centre of gravity shifts, and pressure points at the hips and shoulders intensify, especially for side sleepers.
Dorothy, our sleep specialist at Mattress Miracle, works with expecting mothers regularly: "The most common complaint I hear is hip pain. When you sleep on your side with a growing belly, all that extra weight concentrates at the hip. If the mattress is too firm, it pushes back against the hip bone. If it is too soft, the hip sinks and the spine curves. What you need is something that cradles the hip while supporting everything else."
A mattress with individually wrapped pocket coils does this well because each coil adjusts independently to the weight above it. The coils under your hip compress more while the coils under your waist provide support. Our Restonic ComfortCare Queen with 1,222 individually wrapped coils at $1,125 is a strong option for this reason. Each coil responds to your body's specific pressure profile.
For women who find even a good mattress is not enough in the third trimester, a mattress topper can add a temporary layer of pressure relief without replacing the entire mattress. Choose one that is 2 to 3 inches thick with memory foam or latex for the most contouring.
Firmness Guide for Pregnancy
If you weigh under 150 lbs pre-pregnancy, a plush mattress (4-5 firmness) usually provides enough contouring for side sleeping. Between 150 and 200 lbs, medium (5-6) is typically ideal. Over 200 lbs, a medium-firm (6-7) prevents excessive sinking while still offering pressure relief. These are general guidelines. Every body is different, which is why we encourage trying mattresses in person at our Brantford showroom.
Pillow Strategies That Actually Help
- Between the knees: Keeps the pelvis aligned and reduces strain on the hips and lower back. This is the single most effective pillow placement during pregnancy.
- Under the belly: A thin pillow or folded towel under your belly takes weight off the side you are lying on and reduces pull on your back muscles.
- Behind your back: Prevents you from rolling onto your back during the night. A regular bed pillow works fine for this.
- Under your head: Your regular pillow, but consider whether it is thick enough for side sleeping. The gap between your ear and the mattress surface needs to be filled to keep your neck aligned.
- Full-body pregnancy pillows: C-shaped or U-shaped pregnancy pillows combine several of these functions into one. They are bulky but effective, especially in the third trimester.
Visiting Our Showroom While Pregnant
We genuinely encourage expecting mothers to visit our Brantford showroom at 441 1/2 West Street and lie on mattresses in their actual side-sleeping position. Bring your favourite pillow. Spend 10 to 15 minutes in the position you actually sleep in. Your body will tell you immediately whether the firmness is right. Dorothy works with pregnant customers regularly and understands the specific support needs at each stage.
Find Your Perfect Mattress at Mattress Miracle
We are a family-owned mattress store in Brantford, helping our community sleep better since 1987. Come try mattresses in person and get honest, no-pressure advice.
441 1/2 West Street, Brantford, Ontario
Call 519-770-0001Frequently Asked Questions
Can I sleep on my back while pregnant?
In the first trimester, generally yes. After about 20 weeks, most healthcare providers recommend avoiding prolonged back sleeping because the weight of the uterus can compress the vena cava and reduce blood flow. If you wake up on your back, simply roll to your side. Consult your doctor for advice specific to your pregnancy.
Is it okay to sleep on my right side during pregnancy?
Yes. While left-side sleeping is theoretically optimal for blood flow, sleeping on your right side is also safe and far better than sleeping on your back in later trimesters. The most important thing is to avoid prolonged back sleeping after 20 weeks. Do not stress about which side you wake up on.
What mattress firmness is best for pregnancy?
Medium to medium-plush (5-6 on a 10-point scale) works for most pregnant women who are side sleeping. You need enough give to cushion the hip and shoulder without so much sinking that the spine curves. A mattress with individually wrapped coils, like our Restonic ComfortCare with 1,222 coils, adjusts to your body's specific pressure points. Visit us at 441 1/2 West Street to test in person.
Do I need a pregnancy pillow?
Not necessarily. Many women do fine with regular pillows arranged strategically: one between the knees, one under the belly, one behind the back. A dedicated pregnancy pillow (C-shape or U-shape) is more convenient but takes up significant bed space. Try the individual pillow approach first and upgrade if needed.
Can an adjustable bed help during pregnancy?
Yes, particularly for women with nausea, acid reflux, or shortness of breath. Elevating the upper body reduces reflux symptoms and makes breathing easier as the baby grows. Our adjustable bed bases work with most mattresses and can be a worthwhile investment that continues to be useful long after pregnancy. Call (519) 770-0001 to ask about options.
Visit Our Brantford Showroom
Mattress Miracle
441 1/2 West Street, Brantford
Phone: (519) 770-0001
Hours: Mon-Wed 10-6, Thu-Fri 10-7, Sat 10-5, Sun 12-4
Our team has 38 years of experience helping customers find the right sleep solution. Call ahead or walk in any day of the week.
Visit Our Brantford Showroom
We are located at 441½ West Street in downtown Brantford. Free parking available. Our team does not work on commission, so you get honest advice based on your needs.
Mattress Miracle , 441½ West Street, Brantford, ON · (519) 770-0001
Hours: Monday–Wednesday 10am–6pm, Thursday–Friday 10am–7pm, Saturday 10am–5pm, Sunday 12pm–4pm.